© 2009, 2010 www.theCUBEstudio.com
This review is a ‘living
document’ and is being updated as new information becomes available. The link
does not change, so to follow the progress, just hit the link again to get the
latest version.
This review and comparison
is a documentation of the author’s experience in using the mentioned products.
This is a ‘user review’ and not a ‘buying guide’ nor is it intended as a
representation of suitability of a particular purpose or an endorsement of any
product. The author was not compensated
by any of the vendors.
http://www.thecubestudio.com/ServoDriveReview.htm
Revision 00 07/01/2009
initial release
Revision 01 07/05/2009
added info on Leadshine and Tek10
Revision 02
07/15/2009 added partial review
info on Leadshine
Revision 03 07/16/2009
completed review of Leadshine.
Revision 04 07/18/2009
completed review and summarized.
Revision 05 07/22/2009
Added AMC and Granite to lineup (future tests).
Revision 06 07/24/2009
Added DMM to lineup. Updated summary with Rutex response.
Revision 07 07/27/2009
Updated pricing on Granite drive.
Revision 08 07/30/2009
Edited for publication.
Revision 09 08/03/2009
added Update to Rutex setup, deleted AMC drive from lineup.
Revision 10 08/05/2009
added vendor comment from Leadshine
Revision 11 08/07/2009
added CNCdrives Whale3 to lineup and started some review sections.
Revision 12 08/11/2009
added CNCdrives Dugong to lineup Vendor comment from Larken (Viper)
Revision 13 08/13/2009
removed DMM from lineup. Update to Viper research. Update CNCdrives tech
support. Highlighted all updates.
Revision 14 08/26/2009
finished review of Whale3 and Dugong drives .
Revision 15 09/02/2009
added update on Whale3 to Warranty and Tech Support section
Revision 16 09/04/2009
added update to CNCdrives in Researching section.
Revision 17 09/09/2009
added CNCdrive comment to Vendor Comments Section, Added update to
Granite drives lineup description.
Revision 18 09/24/2009
added update on Rutex drive burn out. See Warranty section and
conclusion section.
Revision 19 10/28/2009
Review finished and closed. Update to Granite drive review status.
Vendors may continue to provide updates for inclusion.
Revision 20 05/25/2010 Review reopened to include
Granite Devices VSD-EX NEW WINNER!
Revision 21 06/24/2010 Categorized drives and added
‘Best Choice’ for drives below 100V, added updates to Dugong and VSD-XE drives
under various headings.
Revision 22 08/06/2010 Added AC Servo category and two
Mitsubishi drives and motors. Updated ongoing issues with the Granite VSD-EX and
Dugong drive.
- DC Brush
Servo Drive Review and Comparison -
UPDATE: Vendor provided info: replaced
by Gecko320X as of 08/07/09 new price $114)
Leadshine
810 ( 80V 20A
$119 + $12 ship from US)
CNCdrives
Whale3 ( 80V 20A
$107 + $22 ship from Hungary)
CNCdrives
Dugong ( 160V 35A
$170 + $22 ship from Hungary)
**Granite
VSD-EX ( 160V
40A $290 + $23 install kit + $25
tuning cable + $60 shipping)
***DMM
Dyn2-B-8 (removed
from consideration due to small fixed following error)
****TEK10 ( 80V 25A
$309 + $?? ship)
*AMC DX15C08C GE1 (removed from consideration due to OEM CAN interface)
-
- AC industrial servo drives Review and comparison -
Mitsubishi
MR-Cxx drive with matching HCPQxx Motor
Pricing info
and performance review to be added soon
Mitsubishi
MR-J2S-xxA drive with matching HC-KFSxxK motor
Pricing
and performance review to be added soon
* This drive is about $800 new, but readily available used
for $50 to $250. It is included as a yardstick for comparison to the high end.
The product that I
have for review is an older OEM used drive which uses the CAN interface only,
and a functional CAN-to-PC converter is over $100 putting the drive out of the
price point being reviewed, so this drive will not be reviewed.
Interestingly, AMC
claims that ALL Digiflex drives have an RS232 interface, but obviously that is
not the case. If a used or surplus drive with an RS232 interface becomes
available, I will review it.
NOTE the following paragraph no longer is applicable: ** By
request, Granite drive may be added later. The drive cost is $240 or $290
depending on model at current exchange rate. You also need a special cable $27
and an install kit $24. Shipping is from Finland or New Zealand and varies
apparently between $12 and over $100. I have asked (on their CNCzone forum
section) if there is a US vendor, no response. The drive is rumored to control
two independent servo motors, but there is no official note of that on the
company web site. The company states that stepper motor support is
‘preliminary’ so it makes sense to wait until that is completed before testing.
UPDATE:
Granite drives has announced that their drive will support two independent
servo motors with a user installable firmware update.
The product is being sold by
Keling Technology but I was unable to determine if Keling has the new 160V
models or the older models.
UPDATE: the
Granite product is no longer listed on the Keling site.
NOTE the following update is no longer
applicable: UPDATE: I have decided not to review the Granite drive. I want to
be very clear that this is not because of any specific problem with the
product. My focus in this review was DC brush motors and the Granite drive
(inclusive of ‘install kit’ and extraordinarily high shipping cost) is simply priced
out of that specific market, in my opinion. The use of brushless drives either
DC or AC is a different story and if that were to focus here, the higher cost
of the Granite would not be an issue.
UPDATE:04/19/2010, I will now review the Granite devices newest
drive model. Granite has upgraded the
drive to 160V and has a new XE model that provides a peak of 40A for a single
DC servo motor. In addition, the drive has been updated to handle two separate
DC brush motors, effectively halving the cost of the product. In the works is
new firmware that can operate a stepper in closed loop with an encoder and
reach speeds as high as 7,000 RPM. This capability is new and as yet
unreleased. The stepper functionality is in
beta testing.
***By request, DMM drive may be added later. This AC
brushless drive is bundled with a 250watt AC NEMA34 motor, cables and software
for $250 plus $30 shipping from Canada to the
US. This product seems like a ‘must have’ product, but so far, I can
find nobody at all who has used this product. Their web site is new and very
sparse. They have only recently created a presence on Ebay and show no sales of
the complete setup yet. It does have a money back guarantee, so I may review it
anyway.
UPDATE: DMM
drive will not be reviewed due to lack of interest together with some
performance details noted in a close read of the specs, notably a very small
fixed following error.
UPDATE:
04/29/2010, DMM now has a 400watt motor. The following error is now adjustable,
but remains at only 128.
****TEK10 will not be reviewed because the specs show it to
be basically an overpriced Gecko. Trip limits are fixed at 128 or 1024 and it
is tuned with an Oscilloscope and trim pots like the Gecko. No software tuning.
Researching:
GECKO 340 the Gecko
site is a treasure trove of information and calculations for both steppers and
servos. There are several excellent tech papers on the site and the product
manuals are available for download so that you can read about the products
prior to purchase. I found no inaccurate information or deceptive claims on the
Gecko site. The Gecko product line is extremely popular and information on any
of the products is readily available on many forums.
RUTEX 2010 the Rutex site likewise has a great deal of
general and specific information on their products and downloadable manuals and
tech papers. Rutex suffers from a deserved bad reputation due to problems with
the 2020 model drive and perhaps its predecessor as well that have a tendency
to burn out far below rated capacities. Rutex acknowledges the problems with
the previously mentioned drives, and claims
that the 2010 reviewed here does
not have that problem, but it is very difficult to dig up any information,
reviews or opinions on this model. I found no inaccurate information or
deceptive claims on the Rutex site.
VIPER 95 the Viper site has very little in the way of general
or specific information. When you click on the link to the Viper 95 manual,
what you get is the manual for the Viper 100/200 with is a totally different
product. Unless you notice this, you will be reviewing information that does
not pertain to the product you are going to buy.
False Claims:
Larken makes the false claim
that they are the only manuf to offer a
money back guarantee. Both Gecko and Rutex offer a money back guarantee and
state so on their web sites. DMM offers a money back guarantee on their Ebay
listing. Leadshine offers a money back guarantee, although not officially.
UPDATE: this claim has been
removed from the site.
Larken claims that they are
the only manuf to offer a 60 day warranty. That is technically true as Gecko,
Leadshine, and DMM offer 1 year and
Rutex and Granite offer two years, but the implication is clear that the
competitors do not offer good warranties.
UPDATE: this claim has been removed from the site.
Inaccurate/deceptive
information:
Larken shows a matrix
comparing their product to Gecko and Rutex. The Rutex product they are
comparing has been out of production for 4 years and the current Rutex models
exceeds the Viper in nearly every category.
UPDATE: the Rutex drive has
been removed from the matrix altogether, so there is no longer a comparison to
the Rutex product. . The Gecko was updated to show a 340X model (actually it
should be 320X)
Leadshine 810 the AMT website has a vast amount of information on
general CNC as well as specifics for their products. Downloadable manuals for
the drives as well as the tuning software, and some informative downloadable
tech papers on CNC setup and various calculations. AMT also sells matched servo motors and the drives can be
pre-tuned to them by the factory. . Very nice for nubees! I have not had time to search the web for
reviews/opinions/support of the Leadshine drives. I will update when I have done
so. I fund no inaccurate information or deceptive claims on the AMT website.
CNCdrives Dugong: same as Whale3. Dugong is a brand new product just
starting to ship and not shown on the web site.
I found no misleading
information or deceptive claims.
Purchasing:
GECKO 340: is easy to
purchase from several different sources as well as from the Gecko site. On-line
purchase and payment is available as well as stock status and product is in
your hands in a couple of days . . well
packaged and often with a little stuffed Gecko. Shipping and tracking
information was provided via E-mail.
No additional parts are
needed to install the Gecko drive. The Gecko needs only the motor power and the
normal 5V control signals available from the BOB or parallel port.
RUTEX 2010 is a little
more complicated in that the you can only enter an order on the site and they
‘contact you’ via email. They did contact within 24 hours with a total and the
product was shipped the same day as the paypal invoice was paid. Product
arrived in a couple days. Rutex does not routinely e-mail shipping information
or tracking numbers but will provide the information if you ask for it.
Rutex includes one of the
two required special connectors to install their drive. And you may have to buy a 24V power supply
for the Rutex, unless for some reason you already have 24V available (I
didn’t).
VIPER 95 proved quite inconvenient to purchase. You can only
order via phone or e-mail. An e-mail order went unanswered for 4 days until
prodded with follow up e-mail and then a paypal invoice simply appeared which
included a $25 shipping charge. There were more days of silence after that
invoice was paid until prodded again at which time an e-mail from Larken stated
the drive would be shipped the next Tuesday. On the following Thursday, another
e-mail from Larken stated that the drive had not been shipped because they were
waiting on parts (for the drives they supposedly had in stock) and that the
parts were due in the following Tuesday. The drive was shipped the following
Wednesday and arrived a few days later with no invoice or packing slip in the
box. The lack of a packing slip will cause great deal of trouble if you need to
return something to Canada.
Larken charges extra for the
special connectors required to install their drive. The Viper makes its own
logic power from the motor supply voltage, so motor power is all it needs.
Leadshine 810: is easy to purchase from the AMT website or ebay.
Online purchase and payment is available at either place. I ordered the 810
from the AMT website and the product was shipped same day from a US warehouse
with tracking number provided via e-mail.
As with the Gecko, the
Leadshine 810 has clearly identified screw terminals.
The drive arrived promptly,
but the packaging was minimal, especially for USPS shipping. The drive comes in
its own close fitting box with no padding whatsoever and that box was stuffed
into a USPS ‘small box’ with a tiny strip of thin bubble wrap. The drive was
mistakenly shipped without the RS232 tuning cable that is supposed to accompany
first purchases.
CNCdrives Whale3: Ordering is
available on the site via a ‘contact the vendor with an order form’ approach
not unlike Rutex. CNCdrives site offer on-line payment of the order if you are
using Paypal only. I entered the order and within 24 hours had a response that
the Whale2 had been superceded by the new Whale3 (not on the website as of this
writing). They provided a link to the documentation on the new drive and responded
within hours to a few questions about the new model. I am in the process of
purchasing this drive so I will finish this section after I have received the
drive.
Although both the website
checkout and the e-mail invoice they send show a cost identified as the ‘total’
price. After payment is made, they come back with an e-mail stating that you
have to pay a shipping charge of US $22. This charge would cover up to 10
Whale3 drives ordered at one time.
They claim that they are
unable at this time to get their website updated to show shipping charges.
CNCdrives Dugong: same as
Whale3, except shipping charge would cover 4 drives. The Dugong is a brand new product and is in limited supply. They
have promised to ship one Dugong and one Whale3 to me by the end of this week
(08/14/09)
UPDATE. The
drives shipped on the date promised and arrived 6 days later via USPS.
Packaging was adequate.
Granite devices VSD-XE: Online ordering was added to the site less than two
months ago and has an interesting quirk. You can choose between being invoiced
and paying immediately using Paypal. I chose paypal and was surprised to see
close to $400 additional shipping charge added. Backing out and selecting to be invoiced resulted in an immediate
e-mail of an invoice with the correct amounts.
The e-mailed invoice contains
clear instructions for paying with a bank wire transfer or Paypal. Granite’s
international shipping charge US$60 is by far the highest of any of the
reviewed products. Granite states that the shipping is insured. While there is
no indication of it on the site, I recall from previous research that the
charge covers more than one drive, so to confirm this, I placed 4 drives in the
cart and the shipping remained at US$60. The shipping cost increased to $67 for
5 drives.
A US$31 ‘install’ kit contains a mounting face plate and parts to
make needed cables as well as fiber optic cables to accomplish remote
monitoring. A US$30 USB cable is required for tuning the drive. Fortunately, only
one is needed for as many drives as you have, and this cable is a stock FTDI
part and can be purchased directly from FTDI for about $17.
The drive was shipped 4
business days after the order and an e-mail notice was provided.
Package arrived on May 14, 2010. Total time was 16 calendar days after order. Packaging could only be described as adequate.
Setup and Features:
GECKO 340: this drive
is very easy to install and configure. The drive is tiny and all connections
are on the same edge. Wires connect with simple and clearly labeled screw
terminals. The manual has complete accurate diagrams, however, if you use an
encoder which exceeds the Gecko’s ability to supply encoder power, you will be
on your own to get it wired correctly. In such a case, you have to provide
external power and the manual is devoid of information or diagrams on how to
accomplish this. Several e-mails to Gecko support netted some useful information, but after repeated exchanges,
the information required to accomplish the hook-up was still not complete. Thru trial and error, I eventually
discovered that the Gecko had to be separately grounded back to the BOB in
order to read the encoder with external power.
The Gecko manual does not
explain the relationship between the encoder count and the step multiplier, and
therefore the formulas provided can be misleading. The manual also makes some
references to additional requirements to run ‘small’ motors, but does not
quantify what ‘small’ means, so that information is not useful.
The Gecko has no tuning
software available for it and it does not communicate at all with a computer.
The drive is tuned in real time via three pots on the back edge of the drive.
The parameters are explained well in the manual and the real-time tuning is
quick and easy with clearly audible feedback from the motor as you turn the
pots. There is a fairly large range of adjustment within which the motor is
happy, which makes the use of an oscilloscope a luxury rather than a necessity.
No additional parts,
connectors or tools are needed to install the Gecko drive. However, Gecko
recommends using an oscilloscope to tune the drive.
RUTEX 2010: Rutex offers
a mother board which eliminates both the mounting and wiring requirements and
the drives are clearly designed with that in mind as mounting and wiring is
somewhat complicated and requires the purchase of some odd connectors before
you can even start your install. They
provide the part numbers and a suggested vendor for the connector, but it is
aggravating that they do not include the 40 cent connector that they know you
will need instead of making you pay the 40 cents plus $5 shipping or (in my
case) drive 45 minutes round trip to Fry’s electronics to buy the 40 cent
connector.
Unusual interface: Rutex chose to incorporate an SPI interface
for communication between the PC and the drive for the purpose of tuning. This
uses the same parallel port that is used to actually operate the drive in service,
so you have to figure out how to do both jobs with the same port. The manual
describes the cable you must build to connect directly to a parallel port for
tuning purposes, but I doubt anyone would find that very logical as you would
still have to later ‘unbuild’ that cable and connect the drive you your BOB.
Fortunately, you can start right off connecting the drive to the BOB and
provided you use the specific pins that the Rutex tuning software requires, you
can communicate from the PC to the drive for tuning purposes using the existing
CNC connection. However, this will still prove problematic with more than one
Rutex drive to tune as you would have to connect each drive in turn to the PC
for tuning and then reconnect to the BOB. Small tweaks to the tuning would
prove very inconvenient.
UPDATE:
Rutex claims that when using their motherboard, each drive can be tuned in turn
by selecting it in the tuning software. I do not have the motherboard and
cannot confirm this. There is nothing in the documentation about it.
Rutex provides tuning software
that has a complete set of checkboxes to turn the various features on or off
and set all of the tuning parameters.
The software has several test modes that run the motor thru its paces
and the software graphs the behavior of the drive, thus eliminating the need
for an oscilloscope. The software works well, but does have bugs and some room
for improvement. The SPI interface chosen by Rutex is unstable and during
tuning, the link goes south frequently causing the drive to need resetting and
loosing whatever parameters you were working with that you had not yet saved.
UPDATE:
Rutex acknowledges the unstable SPI interface and claims to be working on and
update that will fix this.
There is not a lot of info
available from users or from Rutex Tech support offering specific suggestions
of reasonable values to use for specific motors or even for motors of a certain
size or power. Rutex tech support seems as baffled as everyone else on exactly
how to tune the drive, or what the mysterious Kd index is for. It is basically
all guesswork and tuning the Rutex can only be described as an arduous hit or
miss process that will consume hours of your time and much of your hair.
VIPER95: This drive proved very difficult to install as the
connectors come off all different sides of the drive and the drive has several
different styles and sizes of connectors, only one of which is easy to
use. You much purchase and pay
separately for the several special connectors that are required to install the
Viper. If you do not notice this during your purchase, you may have to endure a
long delay and another hefty shipping charge waiting for the connectors before
you can even get started installing.
The connector pack comes with some very tiny contacts that must be
crimped onto the wires and then inserted into the equally tiny connectors.
Fortunately I already had a crimping tool so I did not have to buy the $40 tool
recommended by Larken to make up the required cables. Still, I had a difficult
time dealing with such tiny pins, many of which were only making intermittent
contact after assembly and had to be disassembled again and ‘tweaked’ to make
good contact. As with Rutex, this practice of not supplying required special
connectors and in the case of Larken, not providing a pre-assembled connector
with pigtails is just unfathomable to me.
Trying to install the Viper,
you quickly discover that the manual you were provided is not for the product
you have in your hand. The manual shows pins that do not exist on the product
you have and there is basic information missing; for example the polarity of
the power connections and the orientation of a row of jumpers, requiring
several emails to Larken just to get enough info to get the product installed.
With things finally wired
up, I discovered that despite Larken’s claim, the Viper does not support the
latest E6 model US Digital single ended encoder. After numerous e-mails back and forth with Larry Kenny (the owner
of Larken) he eventually stated that there was ‘a way’ to make the encoder
work, but would only say that the diagram would be in the ‘next manual’ and did
not provide the information to get the encoder working. I continued the
evaluation with a small 300 line encoder that did work with the Viper.
The Viper faulted constantly
during tuning and to reset the drive required powering down the main power
supply and waiting for the caps to drain. More e-mails to Larry Kenny confirmed that this is the only way to reset
the drive. When I informed him that the manual I was provided for the Viper 95
from his web site clearly showed the drive could be reset via cycling the 24V
control power, and that killing the power to the whole CNC machine, including
the steppers, was a deal breaker, he then said that there was ‘a way’ to reset
the drive from one of the connectors, but again he failed to provide that
information, claiming it would also be in the ‘next manual’. He provided dates
by which he would send the ‘next manual’ but those dates came and went with no
manual showing up, so I was unable to configure the planned encoder, nor reset
the drive without constantly having to power down the entire power supply.
Tuning the Viper is done
thru an RS232 connection using the crude DOS text based HyperTerminal program
included with the PC operating system. Commands to the VIPER are simple single
letter commands that return decimal or Hex values.
The continuous e-mail
exchanges with Larken needed to get this product going serendipitously
uncovered the fact that there are several undocumented parameters that are
required to do the tuning. One of these critical parameters is the following
error. The following error can only be set to a few thousand counts, but even
if that was enough, the value is not saved in the EEprom of the Viper,
therefore the Viper75/95 cannot be successfully tuned for applications where
the low default value is not acceptable.
UPDATE:
Larken claims that a firmware bug preventing the parameter save has been fixed.
I no longer have a Viper drive and cannot confirm the fix. Firmware updates
require the drive to be returned to Larken in Canada at customer expense.
There is no software at all,
let alone graphing software and the manual is silent as to how to use an
oscilloscope to peer into the drives performance, so in effect the Viper is a
tune by the ‘seat-of-the-pants’ process at best.
Leadshine 810: This drive
is supposed to ship with a ‘special cable’ needed to connect it to a PC for
tuning. For the signal side connectors , you will need a jeweler’s screwdriver,
as the terminals are tiny. Like the other drives in this review, the screw
terminals are actually on plugs so once all of the connections have been sorted
out, the drive can be simply unplugged for relocation or repair.
The Leadtech tuning software
functions exactly as described. In contrast to the Rutex, the Leadshine drive
stays connected at all times and exhibited no annoying bugs. On the other hand,
the software is ‘minimum essential’ not having the rich feature set of the
Rutex offering. There is only a single trapezoidal motor test, for example. You
can choose among several different parameters for the software to graph and
also select the speed, acceleration, number of loops to perform and the time
period to measure for the motor test routine.
The Leadshine 810 has a full
set of features, but few can be toggled or set to specific values. Notably
absent is any setting for servo loop period. Both Rutex and Larken warn that
this is the most basic critical parameter to set before all else and in the
case of the Rutex, I found that the loop period has a decided effect on the
whole performance envelope. Yet, like
the Gecko, the Leadshine 820 has no setting for this. I’ve asked Leadshine Tech
support about this.
UPDATE: see entry under the
performance heading for the resolution to this issue.
The manual shows a set of
jumpers that must be set correctly inside the drive. To get inside the drive,
you remove the wiring plugs and two screws holding the lid to the base. In so
doing you have to break a QC inspection label. Inside there is a row of pins,
none of which has a jumper on it and none of which are labeled. Tech support
eventually answered that are no jumpers inside the drive. No explanation as to
why the manual instructs the user to go into the drive and set the
jumpers.
CNCdrives Whale3: This new
model only supports differential encoder wiring, but they provide a tiny
translator board free with the drive to convert single ended to differential.
The Whale3 uses RJ45 connectors on the interface converter board and also on
the drive so that a normal twisted pair ethernet cable can be used between the
motor and the drive. The drive provides plenty of 5V power for all of the
encoders I have looked at. HV is thru screw terminals on a plug like the other
drives reviewed here. The control signals are on a separate RJ45 connector
allowing the use of a normal ethernet cable also. Some BOBs have an RJ45 connector as well, but I don’t
know yet is there is any chance of using an unmodified cable between the drive
and a BOB, but they do have their own BOB with enough RJ45 plugs to run 4 axis
plus another for their own relay board and another to take inputs The drive
uses separate 12V power for the logic side, also coming thru the RJ45
connector. The drive can be reset via a pin on the interface without removing
the HV. The drive comes with PC based graphic tuning software which
communicates with the drive thru a standard USB cable and remains active in
real time during operation of the drive for the purpose of monitoring the
following error (and perhaps other functions)
UPDATE: The
drives arrived and bolted right into the pre-made holes in a new mounting
plate. The ability to rely on a vendor’s product dimensions (and mounting
holes) is important if one wants to
pre-build a control box prior to having the physical drives in hand.
CNCdrive includes, free of
charge, a small circuit board to convert a single ended encoder to
differential. The board has screw terminals for the encoder wires and an RJ45 for
the cable to the drive. A manual
clearly shops how to connect the encoder and a standard CAT5 or better network
cable goes between the interface board and the drive. It woks perfectly with a
few different encoders that I tried. I did not connect a differential encoder
directly to the drive.
The power and motor wiring
are done to screw terminals on a plug fitting that is included with the drive.
Terminals are clearly marked.
The drive communicates with
a PC for tuning purposes with a standard A-B type USB cable. The tuning
software is a little bit complex to install because you have to set up a
virtual COM port in the PC by
installing Microsoft .NET and also a utility program that creates a ‘virtual’
COM port. Clear instructions are provided for how to do all of this and the
utilities automatically install just like any other driver.
The tuning software,
‘Servoconfig3’ is new and under active
development, but it functions as described and exhibited no glitches during the
tuning process. It does not interfere with the operation of other USB devices.
The documentation, as has been typical of all of these products, is inadequate
when it comes to guidance for tuning the drive. Basic explanations of the various
parameters are provided and a couple of example screens and you are then set
adrift. CNCdrives delivers the drives
pre tuned for their own motors. The vendor has had automatic tuning for certain
previous models and claims to be planning to add that capability to these new
drives.
The tuning is accomplished
by setting PID parameters and doing a servo move which is then automatically
graphed. This iteration process continues until the drive is tuned. The
software has only one mode to move the motor and you can set only the distance
moved. I found this to be incredible Spartan in contrast the rich set of
diagnostic moves available in the Rutex software. Then it occurred to me that
since this tuning software reportedly can show following error in real time while
MACH is running, perhaps it could also tune with MACH running.
Incredibly, while MACH is up
and running and controlling the drive, the tuning software can ALSO be running
and tuning the drive in real time. This capability allows you to use MACH itself
to perform the needed diagnostic moves. This proved extremely convenient and
accurate as any change in the tuning parameters could be immediately tested in
MACH.
The RJ45 ‘main’ connector is
well documented. I had no problems connecting it up by simply cutting 8” or so
off the ends of an old Ethernet cable and hooking the appropriate wires to my
BOB. Most RJ45 connectors are clear plastic so it is easy to determine which
wires go where. Ethernet cables are available anywhere and are very inexpensive
for the suggested CAT5 quality.
The error line does not have
enough power to operate an LED nor a pin on the BOB reliably. The solution is
to use a transistor to power the LED and BOB pin using 5V from the BOB and
letting the ERROR line simply trigger the transistor.
The drive has a reset pin .
. and that’s about all they say about
it. It is up to the user to figure out how to use it. The drive resets when the
reset line is grounded, so a simple momentary contact puss button is all that
it needed on the control box to reset the drive. You do not need to shut down
either the motor power NOR even the digital power (5V) to reset the drive. The
drive can also be reset via the tuning software.
CNCdrives Dugong: similar to Whale3 and uses the same tuning software.
Power connectors are much larger and include separate terminals for the
braking resistor. Perhaps the most important feature of this new drive is the
automatic brake resistor. HV is monitored and above a set limit, power is
dumped to the braking resistor thereby protecting both the drive and the motor.
This should prevent the burnouts that happen with the Rutex and Viper
drives. The drive can live with a 1 ohm
resistance which eliminates the need for a voltage killing series resistor as
is needed with the Rutex. No sizing calculations for the braking resistor are
included in the documentation.
CNCdrives claims that brake
resistor calculations will be added to a future updated manual. Absent that
info, CNCdrives states that they are going to provide a properly sized resistor
with my order without charge.
The Dugong has individual
screw terminals for all HV power. This not only has the current capacity, but
provides a very secure connection and is easy
to attach large gauge wire because you can simply use the appropriate
size lug for the wire you are using and not have to worry about trying to stuff
large wires into small gripping holes, and the wires cannot get unplugged or
vibrate loose.
Tuning is done identically
to the Whale3 using the same software.
UPDATE
06/24/2010: Since the introduction of the Dugong over a year ago, CNCdrives had been continuously promising to
add new features to the drive, but thus far, no new features have been added.
The company has become unresponsive to queries about the status of any new
features.
Granite devices VSD-XE: Granite now has a special parallel Break Out Board
that appears to provide an easy, clean and correct connection of up to 4
drives. For this review, I am adding a
single Granite drive to an existing setup that already has two BOBs and
therefore did not purchase the special Granite Devices BOB. The Granite BOB
comes at a relatively high cost, but for a new install with multiple drives, it
may be worth the price in time savings booth in setup and ongoing maintenance.
The drive uses the ancient
DB25 connection for the motor. This connector was not designed for power and in
order to use it in that capacity, Granite uses multiple pins in each power line
to get the current capacity. This odd scheme is made a bit easier by the
inclusion of a small PC board that the user is required to solder to the DB25
pins. This PC board groups the DB25 pins into 4 heavy duty solder points to
carry the motor power. These little
boards are supplied with the drive and not the install kit. The install kit has
the DB connectors and covers as well as the header type connectors and ribbon
cable needed for the logic interface. The DB connectors for the motor power and
also the encoder do result in a very slim profile for the drive.
The mounting points on the
physical drive match the dimensions given in the documentation, so control
boxes can be pre-built using the Granite manuals. A very nicely made stainless
steel mounting plate is included in the install kit for mounting the motor
connector side of the drive to a control box. Fiber optic cables are included
in the install kit that will allow the LEDs to be monitored remotely. This is
an interesting approach to remote monitoring. The fiber optic scheme uses no
power, is rugged, simple and is immune to noise.
A typical screw type connector is provided for the
drives power source for both motor and logic.
Note: the HV and 12V logic grounds are connected
internally so users need make sure that their HVDC and the 12V logic source can
have a common ground. The documentation
does not discuss this issue and a question to tech support resulted in this
comment: “It
is recommended to have either 12V or HV supply floating to avoid ground loops.”
Which is
obviously not going to be the case if the grounds are connected inside the
drive. Additional questions cleared up the confusion and apparently the comment
applied to the condition of the grounds BEFORE connecting the to the drive.
Once connected to the Granite drive, the grounds would be common.
Everything about the Granite
product is of the highest quality and also carries a corresponding high
price. For users who desire ‘the best’
and are willing to pay a premium price to get it, this drive will be the one to
have. Only the Gecko, Leadshine and AMC
were comparable in quality.
Unfortunately Granite
provides only ribbon cable for the
header connectors. This would be fine if using their Break Out Board,
which uses a similar scheme, but for
connecting to a third party BOB, users may want to consider purchasing crimp
pin or solder type header connectors so that heavier color coded and shielded
wire can be used.
The tuning software is
reasonably easy to install and functions well. Like many devices, the Granite
drive is not a true USB device but uses an RS232 to USB converter made by FTDI.
A driver is installed in the computer that created a ‘virtual’ COM port and
communicates over the USB to special circuitry in the target device. Granite
uses a cable with the requisite circuitry encased in one of the connectors.
However, there is a very
significant caveat to be aware of; the drive cannot be tuned while the CMD
cable (connection to the BOB) is plugged into the drive. It must be unplugged
before the drive can communicate with tuning software or a ‘communication
failed’ error is generated. I discovered quite by accident that unplugging the
CMD cable cleared the problem. Assuming I had something connected incorrectly,
I questioned tech support for the solution and was surprised to be informed
that this behavior is known to them,
that there is no work around. Granite claims that this behavior is noted
in the documentation, but I did not see this issue described anywhere in any of
the manuals. If one is doing a new install and follows the initial setup
sequence detailed in the ‘getting started’ manual, then coincidentally this
issue is avoided, but in my view, that does not constitute being ‘covered in
the manual.’
Another caveat, although an
understandable one, is that the max and continuous amps cannot be set higher
then the overlimit amps in the tuning software. Users are likely to run into
this restriction because the max and continuous amps settings occur before
(above) the overlimit amps setting. The overlimit setting must be set above the
desired max befor the software will accept high numbers in max and continuous
amp settings. SO one needs to skip ahead to the overlimit, set it high, and
then return to the running limits.
A potential problem is with third party break out board
compatibility. I have two Break Out Boards; a CNC4PC brand on LPT one and a
Homann Designs brand on LPT two. The Granite VSD-XE refused to function with
the Homann Designs board. After connecting to available pins with no success, I
then removed the functioning Dugong drive’s connections from the Homann board
and hooked up the Granite drive to the same pins, again with no success. The
Granite VSD-XE worked perfectly when connected to the CNC4PC break out board.
UPDATE
06/24/2010 UPDATE: The VSD-XE works fine with Homann designs latest MB-02-V6 breakout board.
Overall, the Granite XE was
the most time consuming and complicated installation of all of the drives. To
some degree this is unavoidable because the Granite product can control so many
different types of motors and has so many features that the available choices
in connections, set ups, and tuning parameters are many times more than any of
the single purpose drives in this review.
The granite drive has
several unique features that, for clarity, are covered in context in the
performance section.
UPDATE 08/06/2010:
Some claimed features of the VSD-XE simply
do not function at all. After many communications back and forth about the
specified ‘position reached’ function, Granite Devices finally admitted that
this function does NOT function if the drive is used with Step and Direction
input. It is note worthy that in my initial contacts with Granite prior to
purchasing the drive, I made it very clear that this particular feature was critical
to my application and that I would be using Mach3 and step and direction input.
Performance:
GECKO 340 operates in a mode that Gecko refers to as ‘singing’.
Their explanation for this annoying behavior is that the motor is ‘bouncing ‘
back and forth between encoder counts as ‘required’ to maintain its position.
None of the other drives reviewed do this ‘singing’. The Gecko has a fixed
fault trip of about 128 counts. When that error is reached, the drive faults
and the motor stops. There is no option to change this behavior. With my chosen 1800 line encoder, the result
was constant faulting for what would be harmlessly tiny errors induced by
acceleration or deceleration, that would have been quickly made up in an
instant, had the Gecko not faulted. Gecko is working on a new replacement model
for this drive that will have a fault count that is modifiable over a small
range, but the current Model 340, in my opinion, is unacceptable for anything
over a 300 line encoder.
The Model 340 has a maximum
read frequency of 250k which limited my motor speed to 2080RPM with an1800 line
encoder.
The Gecko 340 runs both 36V
3A and 72V 8A motors smoothly and
quietly (except when holding) with crisp instantaneous stops.
UPDATE: The
replacement model 320X has following error adjustable in steps up to 2048.
Frequency has been doubled to 500k. Note that this is from the spec sheet only.
I have not tested this new drive.
The faulting on the Rutex
2010 can be set all the way into to 30,000 or disabled completely. This is an
important feature for my application driving a 4th axis that serves
as both a holding indexer and also a high speed lathe spindle. The drive can
also be set to fault if it detects and encoder error. This is not so important
in my application, but is a critically important feature is you are pushing a
mill table or gantry with the servo motor. This feature would theoretically
protect against the servo ‘running away’.
It is very unfortunate that
Rutex chose to use the same port for tuning as for running. This prevents any
real-time reporting or polling of the drive during operation, effectively
defeating my plan to read status during operation and make decisions based on that
status.
As mentioned, Rutex has a
less-that-stellar reputation for reliability, but their US rep claims that this
was confined to a specific model and that the 2010 is robust and meets its
specifications completely, although he still posted advice not to set the
current limit anywhere near the drive’s maximum rating, which is inconsistent
with the first claim. I set the current limit to the full 20A spec of the
drive. The motor max draw is 38A. So far no problem.
Viper95: It is hard to say what the performance potential of
this drive is since tuning it requires entering ‘shot-in-the-dark’ values into undocumented, yet critical
parameters, and there is no graphical representation available to display the
actual behavior in real time. However, I did get the drive tuned well enough to
say that it performs very well driving a relatively large (for the review
products.) motor. The Viper 95 is not useful in my application since it will
not accommodate, nor store the very large following errors required for use in
combination ‘lathe/index’ head, and powering down the whole machine including
the steppers (which will then require re-homing) is a definite no-go. However, the drive would be a good performer
on a normal table or gantry axis. It does a very good job holding and displays
crisp stops and is smoother than the Rutex at slow speeds. The drive refused to
run my servo motor up to full speed without faulting, and the smallest error I
could achieve in high-speed steady state even using the specific new ‘forward’
feature was in the 30 to 50 count range.
Here again that would probably not be an issue for use driving a normal
machine tool axis.
Leadshine 810: This will
not be an apples to apples as I am evaluating the Leadshine using only the 36V
NEMA23 motor. However, that motor is very close to the motors that Leadshine
sells for use with this drive. The performance of the Leadshine DCS 810 can be
described as lackluster. The holding is abysmal and there is no combination of
settings I could find that would make it hold or stop sharply without
overshoot. The drive should have had no problems at all with a small NEMA23
motor, but it could not run the motor in the same crisp fashion as the other
three drives in this review.
Leadshine tech support has
confirmed that there is no way to reset this drive other than shutting down the
main power supply. The software manual shows that a fault can be cleared on a
special error screen, but this does not work.
There is no setting for the
servo loop period, which both Rutex and Larken say is a critical setting.
However, the Gecko seems to work fine without a settable loop time, yet the
loop time setting in the Rutex has an extreme effect on the behavior of the
motor, so as with the ‘singing’ behaviors mentioned earlier, the manufacturers
contradict each other. I have asked
Leadshine tech support about this and got a curious answer that the drive is
adjusted via PID which is ‘more powerful’, which makes no sense.
UPDATE:
More queries to Leadshine tech support resulted in an additional response that
the tuning software that they provide does not tune ALL of the parameters (one
of which presumably is the loop time).
For that you need the ‘special’ version of the software. They provided a
link to the ‘special’ version, but my evaluation is completed and the drive has
been returned to Leadshine so I will not be doing anything with the ‘special’
version.
During my testing, the DCS
810 drive began to show an encoder fault. Checking the encoder on the Rutex
(which displays the encoder output in real time) showed it to be working fine.
It was not possible to clear the error
via the tuning software, even though the software has an ‘erase error’
function. A differential encoder was tried with the same result. Only after powering off the main power 10 or 15 times
would the drive reset the fault. It would then run the ‘roadrunner’ program for
a while and fault again. Note that this is an encoder fault and not a following
error fault. i.e. the drive thinks there is something wrong with the encoder.
CNCdrives Whale3: The Whale3 performance is excellent. Even without
spending the time required to get a really refined tune, after just a basic
tune for each motor, this drive runs both a 72V 8A and a 55V 5A motor in
equally excellent fashion. Both motors are silent when holding, run very
smoothly at slow and high speeds and both motors are pushed to their absolute
maximum RPM. Stops are crisp and
following error is only a count or two at full speed.
The Whale3 could not achieve
maximum acceleration from the 8A motor because of the drive’s20A limit. The
larger motor can draw nearly 40A and the 20A limit was apparent when the
acceleration were set very high.
CNCdrives Dugong: This is a big
drive with big performance. I only tested this model with my largest motor, the
72V 8A Keling. With the drive’s 35A limit, the motor acceleration and
deceleration is crisp. Setting extreme accelerations and speeds in MACH, very
far beyond anything remotely useable in machining, generated large following
errors on acceleration, but the Dugong quickly caught up and ran the motor at
full speed with a error count of only 1 or 2 with an 1,800 line encoder.
The motor was silent while
holding and ran smooth at all speeds.
The test motor is on my 4th
axis and after an initial tune, I put the drive belt on to see how the drive
would do pushing a load. The 4th axis was sitting on the floor in my
office. It is heavy. I gradually increased the acceleration and ran a test
program. I did not get to the max acceleration because I had to stop the test
at a point where the 4th axis began to jump around on the floor from
the sharp acceleration/deceleration.
The Dugong needs only a 1
ohm armature resistance so no series resistor is required and therefore the
motor gets full voltage at all times. This alone made a very noticeable
difference over the Rutex drive which required a 1 ohm series resistor, cutting
20 volts off at MAX torque.
Additionally, the automatic
braking resistor will allow me to safely test the 4th axis to it’s
ultimate potential; spinning a chuck with a heavy workpiece. The large voltage
generated on decelerating this ‘flywheel’ mass will be automatically dumped to
the braking resistor if the drives voltage limit is exceeded (unlikely).
UPDATE:05/14/2010,
A few months ago and after the review of this drive was completed, I discovered
that when using a step multiplier, the drive exhibits some bad behavior. The
motor runs roughly at low speeds and cycles thru odd pitch changes while it is running.
Related to this are two other anomalies.
During tuning, the step response also cycles every other step with
sometimes considerably different traces. These first two behaviors have no
practical effect, however, the third symptom can be a serious problem.
Sequential small jogs (.001”) also are not consistent, cycling between a larger
and smaller actual movements. This behavior was reported to CNCdrive and they
indicated that this would be fixed promptly. Later they claimed they could not
reproduce it. I then sent an audio file demonstrating the clearly audible pitch
changes and also screen captures of the alternating step response traces in the
tuning software. Then they acknowledged the problem but numerous queries over
the next several months about progress in fixing the problem were answered with
that same response each time; that it
was impossible to correct because they could not reproduce it. Eventually, many months after the problem
was reported, CNCdrives provided a beta firmware that improved the behavior
slightly, but the drives dithering was
increased significantly.
UPDATE:
06/24/2010, The above mentioned problem has not been corrected and CNCdrives
has become unresponsive to inquiries about it.
UPDATE:
08/06/2010, Still no corrections to this problem or other issues with the
product. No response from CNCdrives.
NOTE: the
CNCdrive smaller ’Whale’ drive does not
exhibit this behavior.
Granite devices VSD-XE:
The performance of this
drive is on a different level from the others in this review. Only the Rutex is
competition for the excellent performance of the Granite drive. The best way to
describe the performance of this product would be to take the best performance,
best features and best tuning software from each offering and combine them into
one product.
The Granite VSD-XE has
completely smooth running and silent holding performance, even with large step
multipliers. None of the other drives have this combination, probably due to a
pair extraordinary features that only the Granite product has;
First, the Granite has a
selectable ‘input smoothing’ feature which makes the drive run with very large
step multipliers as if it were running with none. This is an extremely useful
feature specifically for MACH3 because it effectively eliminates the need for
the smoothstepper or equivalent products in order to get the step frequency
high enough to run the motors at full speed with high res. encoders. The drive
is just as smooth with a 12x multiplier as with 1x even at low speeds.
Second, the Granite has a
separate fully tunable ‘holding zone’ that the drive with use whenever the
‘position reached’ condition is active. The size of the zone, in encoder
counts, is user configurable. The zone has its own PID settings separate from
the main PID tuning.
Unfortunately, like the
Rutex, the Granite cannot be tuned while connected to the CNC control, which I
find to be inconvenient, but the Granite tuning software is better in most
respects and is much better documented and has no unexplained ‘mystery setting’
like the Rutex.
The Granite has none of the
bad behaviors of the Dugong with step multiplication active. The motor runs
smoothly and silently at any speed, does not dither while holding and most
importantly, it has even consistent steps while jogging.
The Granite is the only
drive in this review that can be disabled on command and continue to track the
encoder. Once re-enabled, the drive uses a separate, user configurable set of
parameters to return to the correct coordinates, so the machine does not have
to be rehomed in the middle of a job. In my view, this feature alone makes the
expensive Granite drive worth the price. The ability to disable the drive makes
it suitable for use with a 4th axis or a mill spindle drive. These
applications need to have the spindle released in order to conveniently change
tooling or center a workpiece in a 4 jaw chuck, or to access the adjuster on a
boring head, for examples.
Another unique feature of
this product is an external pin signaling ‘position reached’. This feature
makes the drive perfectly suited for 4th axis duty where the spindle
will be locked when it is stationary for heavy duty applications like holding a
trunnion table of offset drilling.
Any one of the above
features, unique to the Granite drive (of the drives reviewed here) in my
opinion, make the drive worth it’s high cost . . provided of course that you
have a real need for these features. In my 4th axis application, I
need all of them.
UPDATE:
08/06/2010, As noted above, it has come to light that certain features of the
VSD-XE are non-functional. While this is known to Granite Devices, they have
made no mention of this in their documentation or web site.
The XE version of the drive has a very high quality specially
machined ribbed aluminum heat sink which increases the drives ratings. For
extreme duty, the drive can be easily and effectively fan cooled.
Warranty and Tech support:
Note
that no mention was made of this review to any of the vendors. Vendors were not
given the opportunity to provide products for testing and all drives were
purchased on the open market. Therefore the experience and behaviors described
in this review are what any new customer might expect.
Also
note that drives at this price point are considered by many to be ‘hobby’ level
products. However, although I personally am unaware of any of these products
being used in production environments, they are definitely used by commercial
shops. Therefore the standards I applied are based on my 30 years of dealing
with industrial suppliers, the vast majority of which employ very
knowledgeable, competent and professional people in both their marketing and
engineering support groups.
GECKO 340: Gecko offers a money back guarantee for a reasonable
period and a generous warranty. While
Gecko products have the reputation as being top tier in reliability, I had the
occasion to use the warranty for a failed Gecko203V and the service was
exceptional.
Tech support is available
all over the place with Gecko specific forums and any Gecko questions are
quickly answered. My tech support questions directly to Gecko, both pre and post sale have been answered by
Marcus, whom I believe is the designer of the drives. I found him to be very responsive,
knowledgeable and very matter-of-fact in his answers.
RUTEX 2010: Rutex apparently is an on again off again company
with extended periods of inactivity in their history. For a couple of years
they have had a US rep that maintains products in stock for immediate shipment
or replacement under warranty and does tech support for questions asked
directly on the Rutex site. That rep is Tom Eldridge and his forum posts go
back several years so there is some credibility, in my view, to Rutex’ claim to
be making a concerted effort to improve their reputation and visibility in both
the industrial and hobby markets in the US. I have read numerous instances
where drives have been replaced no question asked including those that have
been out of production for several years. I have had my e-mail questions
promptly answered, although not always with a useful explanation of some of the
more esoteric features of the drives that I suspect only the designer himself
fully understands. Rutex needs to produce more comprehensive documentation on
the PID tuning and especially the mystery Kd index parameters and include
sample reasonable values as a guide rather than leave their customer base
wondering if 100 or 9,000 is closer to the correct setting.
UPDATE: The Rutex
2010 drive suddenly burned out for no apparent reason. It seems to have taken
the PS with it. On power up, the motor on the Rutex ran continuously in one
direction. I connected the tuning software, reset the drive and the encoder and
then turned the motor power back on. At that point there was a pop and smoke
from behind the Rutex drive.
I have reported
the failure on the Rutex Web site and asked about repair service and got no
response. I then emailed directly to Tom Eldridge, the Rutex rep. No response so
far.
See additional
comments in the conclusion section.
VIPER 95: A
warrant of only 60 days does not inspire confidence. Considering that as
of this writing, Larken still does not even provide a manual for the VIPER75/95
products that they claim to have ‘sold hundreds of’, it is surprising to me
that the owner Larry Kenny can have a sarcastic and condescending manner in
dealing with the inevitable flood of questions that come his way just in order
for a customer to get the product working at all. He claimed that he had the
solutions to the failings of the Viper95, but refused to provide those, instead
simply insisting that the information would be the ‘next manual’ and leaving me
hanging with a non-operational product for over a month, and making broken
promises as to when the ‘next manual’ would be delivered. He ultimately stooped
to name-calling, saying that my questions were “smart ass” and that I was
creating a “pissing contest”. I found his behavior unprofessional, and
ultimately I chose to return the drive for a refund, which he issued promptly
on receipt of the returned product.
Leadshine 810: there is no mention of a money back or satisfaction
guarantee on the AMT website or the product manual, although they did refund my
purchase price including the shipping cost when the drive proved unsatisfactory
for my purposes. The Leadshine 810
drive carries a 12 month warranty.
Leadshine tech support was
initially slow to respond to questions. When I suggested that I would need to
return the drive the response got much better. Ultimately, both the US
marketing rep and the Leadshine tech support people displayed a genuine
interest in resolving the issues even after they knew that I planned to return
the product. I made some specific suggestions on how they might better
accommodate the machine tool market and they were quite receptive, even to the
point of passing some of the suggestions along to management and reporting back
that actions were going to be taken to address the issues. While the specific product,
in its current form, was not acceptable for my purpose, the behavior and
professionalism of the Leadshine and AMT personnel were in line with the higher
end industrial vendors that I am accustomed to dealing with.
CNCdrives Whale3 and
Dugong: The written 15 day
money back guarantee shows a lot of confidence in the product, and eliminates
the risk (other than one’s time and shipping cost) of trying the product. A one
year warranty is offered without a lot of disclaimers. Pre-sale support was
provided within hours and ALL questions were answered in the first response.
The vendor is unaware of this review and I will update when I have had a chance
to use their tech support.
I have had numerous
discussions with the designer of the CNCdrives products and he is extremely
knowledgeable about the products, about PID tuning, about DC servo motors,
about CNC in general, about competing products, and also demonstrates a rather
in-depth knowledge of Mach3. I have asked multiple questions in a single
e-mail and so far, ALL questions have been answered in the first response. Thus
far, his demeanor is professional and responses are complete, useful, and usually same day.
UPDATE: During
my testing of the Whale3 drive, I made a wiring mistake that left the Whale3
motor outputs wired to either side of a 1 Ohm power resistor. The drive
withstood this abuse for about 20 seconds or so until two traces vaporized in
the power output side of the board. I fixed the wiring problem and repaired the
drive’s PCB but restoring power to the
drive resulted in immediately blowing
the fuse on the main power supply. This indicates failed MOSFETS (big power
transistors), so I removed them from the drive and checked them out. Three of
the 4 were shorted. I informed CNCdrives that I had killed the drive due to my
own error and therefore I would not be expecting a warranty repair. When I
explained that I was going to attempt the repair myself, they were extremely helpful in providing
detailed information and advice that I needed to successfully repair the drive.
The Whale3 is now back in the control box humming along nicely.
UPDATE:
05/25/2010 Improvements, bug fixes and
new features promised over 6 months ago have not materialized. Two months ago,
CNC drives claimed to be working on fixes and new features, with a new beta
firware imminent. However after a couple of weeks passed with no contact, I
queried the progress and was told that the firmware was not being worked on
during that time because CNCdrives had sold out of all of the Dugong drives and
had none to test with. New drives were not expected for an additional two
weeks, making a total 4 week unannounced delay in the ‘imminent’ firmware
release. Eventually a beta firmware was provided which improved the problem,
but also caused the drives dithering to increase dramatically.
UPDATE:
06/24/2010: At this writing it has been over 9 weeks since I tested this
firmware and reported the results to CNCdrive. During that time several
inquiries about progress have gone unanswered.
UPDATE: 08/07/2010:
Still no resolution and no response from CNCdrive.
Granite devices VSD-XE: The basic drive carries a one year warranty while
their flagship XE comes with two years. Granite web site claims that they have
a zero tolerance policy for hardware failure and software bugs. There is also a
claim to have ‘Premium Support’ which lasts the lifetime of the product.
Pre-sale questions were answered completely within hours. However, questions
asked after the purchase have gone unanswered. I asked via e-mail if the
drive’s ‘position reached’ indicator remained active when the drive is
disabled. No e-mail response was
provided, so I started a discussion on the Granite section of the CNCzone
forum. 8 days after the e-mail question a response was made on the forum
indicating how the ‘servo ready’ indicator functioned. So I asked again on the
forum the same question about the ‘position reached’ indicator function but
there has been no reply.
UPDATE:
05/14/2010 Apparently not all of the Granite e-mail addresses are monitored.
Support emails send to the support e-mail address go unanswered, but if sent to
the sales department get prompt responses.
All questions
were eventually answered and response has been consistent and timely since I
began addressing the support questions to the sales e-mail address.
UPDATE: 08/07/2010:
As mentioned above, it is clear that Granite devices is aware of certain
features that simply do not function and also they are aware that the drive
cannot be tuned while connected to the CNC controls. No mention of these
limitations is mentioned in the documentation and it takes numerous queries to
Granite tech support to finally secure an admission that these limitations
exist. In the case of the tuning limitation, Granite Devices claims that the
limitation is stated in the manual, but it is not.
Conclusions:
The Gecko drive works
very well with small motors provided you have a low count encoder. It is by far
the easiest to connect and tune. Gecko is about to come out with a
‘significantly improved’ replacement, but the couple of specs I got from Marcus
were not significant improvements in my opinion. However, no conclusion should
be drawn about the new 320X drive until the full specs are published.
UPDATE: the
320X has been released and specs are available on the Gecko website.
The Viper was returned
after much frustration with both the product and the support. The Viper 95
performs very will if you stumble across the right settings, but it does not
store the following error setting, limiting it’s applications with a high
resolution encoder, and the Viper’s high price and high shipping cost combine
to put it significantly higher than any of the other drives. If Larken fixes
the firmware bugs and produces the promised manual with the ‘secret’ solutions
included, that might relieve some of the frustration of dealing with the
product, but as of this writing, this choice should be avoided.
UPDATE:
Larken has added the Viper75/95 information to the existing manual to create
essentially a ‘universal’ document. Diagrams for external modifications to fix
the encoder interface and to rig a hot reset are included. This information was
not available at the time this review was written, so I have not tested these
fixes. I will not be retesting any of the Viper drives. The main power polarity
is shown, but the orientation of the rows of jumper pins is still not
identified.
The Leadshine is the
least expensive, but it also has the worst performance, being unable to stop
the motor crisply without overshoot. The only way to reset the drive after a
fault is to power off your main power supply, which is problematic for use on a
machine tool. Leadshine is introducing a new lower cost 810’S’ version of the
drive which uses only single ended encoders and has a reset pin, however, a
close read of the manual reveals that the reset is ONLY applicable to a
following error and all other errors still require a complete power down of the
main supply. The Leadshine 810 , in its current version, also should be avoided
for use on machine tools.
Of this bunch, the Rutex is
the clear winner (see update below), with the
possible caution that reliability might be an issue, based on Rutex reputation.
This product is not without problems and requires a lot of patience to get it
working, but the performance is exceptional and it is the only drive in this
review that does not have constant faulting. The Rutex has good price,
availability, and the performance is exceptional. The only issue is the
inadequate manual, which does not provide sufficient information or examples to
get the drive tuned quickly and easily. The tech support, as I mentioned
earlier was not able at this time to provide useful insight into the cryptic
settings. The interface chosen is unstable and does not stay connected reliably
during tuning. There is no such issue with running the drive however, and thus
far the drive has performed perfectly. If you can find someone using the same
motor that you plan to use and you can get the drive settings from them, and
you pre-purchase the special connector that Rutex should have provided, then
the only obstacles to the Rutex install would be eliminated.
UPDATE: the
RUTEX is now the number two drive in this review having been outdone by the new
WHALE3 and Dugong models.
UPDATE: as
mentioned in the warranty section, the drive has burned out. Rutex has thus far
been unresponsive. As mentioned in the review, Rutex has a reputation for their
drives burning out. Rutex acknowledged this, but claimed it was limited to a
specific mode and that the 2010 was fine. However, they also warned not to set
the drive at it’s full rated power, which I found quite suspicious.
Based on this
experience, the well known Rutex ‘burn out’ problem is not confined to specific
older models. This drive blew out the MOSFETs and one of the MOSFET controller
chips. The controller chip is an L6386 and is listed as ‘obsolete’. Mouser
electronics has no stock and Newark electronics has a note that when their
stock is gone, they will not be getting any more. There is no replacement or
equivalent listed at either of these major suppliers.
The conclusion
is that the burn out problem is not confined to older models as claimed by
Rutex, Rutex is unresponsive to customers with burned out drives, and even the
new models use obsolete parts so it
will be only a short time until the drive are unrepairable due to unavailable
parts. Based on these findings, I have to recommend that Rutex products be
avoided.
The Whale3 and Dugong
drives from CNCdrive are now the top choices in this lineup.
UPDATE: 06/24/2010:
the Whale3 remains the ”BEST CHOICE” among the smaller (100V/20A or less)
drives in this lineup, but after adding and reviewing the recently upgraded
Granite VSD-XE, it is now the TOP CHOICE . See UPDATES under
other headings for the latest info on the previous TOP CHOICE, the Dugong
drive.
Performance is equal to
the Rutex, but there are no significant detractions like mounting problems,
oddball connectors, buggy interface and software and the like.
Documentation is accurate but needs improvement in the area of
completeness. This is understandable given that these are brand new products
and the documentation is available in several languages. The web site, on the
other hand is abysmal and far out of date. This has no effect on the quality
and performance of the products, but certainly cannot be good for business and
in some ways it could begin to be a detriment to existing customers due the
lack of downloadable documentation and software updates for the new products.
Support is exemplary. By contrast, Larken is completely unacceptable and Rutex, while having good
intensions, is more adept at making excuses for the existing shortcomings in
the product features and documentation, as well as their business
practices, than they are at actually
fixing or improving anything. CNCdrives tech support has thus far proved to
have a professional demeanor matching
that of Leadshine, and fast response
with USEFUL answers to ALL questions asked, rivaling the service of Gecko. As a company, CNCdrive are keenly interested
in customer feedback and express a genuine interest in improving the products
and documentation whenever possible, but do not provide false dates or unrealistic
expectations that they then cannot meet.
UPDATE:05/25/2010:
While support from CNCdrives was excellent initially, and they demonstrated a
keen interest in improving the product. Good intensions are admirable, but the
actual results are that the product is in essentially the same condition as it
was at its introduction 11 months ago
when the original review was performed. After the first unsuccessful beta
firmware release 4 weeks ago, CNCdrive
became unresponsive and has provided no updates or ETA on promised improvments.
UPDATE:
06/24/2010: Another month has passed (now 9
weeks after the first unsuccessful beta firmware test) and still there
is no new firmware and no responses from CNCdrive. The conclusion that I reach
is that it has been discovered that the promised fixes, improvements and new
features are not doable.
Cost comparison shakes out like this: Rutex charges $17 for the encoder interface
which CNCdrive provides free. Larken does no offer the interface, but it can be
purchased form encoder vendors for a similar price. Adding the Rutex 2010 ($148) or Viper95 (recently reduced to $148)
drive and interface together, either drive is nearly $60 more than the Whale3.
The price difference between the Dugong and the comparable Rutex2020 of Viper200
is also significant.
Overall, while performance is the number one priority, the
Whale3 and Dugong drive’s intelligent layout, standard connectors, USB
interface and solid tuning software make them far less frustrating to deal with
in terms of installation, setup and maintenance.
Granite devices
VSD-XE: . . the NEW TOP CHOICE. After being added to the lineup, evaluated and compared to
the competing products, the Granite VSD-XE earns the top spot.
Granite and Gecko are
vendors in this lineup that have continued development and made significant
improvements to their products. (note that all of the vendors are aware of this
review and all have been invited to provide updates and/or product
announcements) Since this review was first undertaken, Granite has completed
and released previously announced features like 160V capability, their unique
dual DC brush motor capability, and a motion library. Announced, but not
available at this time is a sophisticated series of stepper motor control
schemes.
Tuning changes cannot be
conveniently tested under CNC control as can be done with some other drives,
because like the Rutex, the Granite drive cannot be tuned while connected to
the CNC. This makes it very inconvenient to tweak tuning since the control box
would need to be opened and the drive unplugged from the BOB before it could be
tuned, and the USB unplugged and the BOB reconnected to test the new setting
under CNC control.
UPDATE:06/24/2010 after spending some time with the product, I
have found the above mentioned (and undocumented) restriction to be an extreme
inconvenience. The inability to tune this drive without first opening the
control box, physically disconnecting the ‘command’ cable, then connecting the
USB cable, (and then going thru a special power cycling sequence each time to connect to the drive for tuning) has
proven to be a very time consuming and restrictive. For example, there is a status screen in the tuning software that
shows the state of various flags and indicators which is functionally useless
since they would only have meaning if monitored in real time while connected to
the CNC with the drive operating a motor. The lack of documentation on the
problem together with tuning software features that would only be useful In
real time, lead me to conclude that real time tuning with the CNC controls
connected was the intent, but that for whatever reason, was discovered to be
unworkable. Granite gave no indication that this would ever be corrected.
While the
Granite VSD-XE is my TOP CHOICE for this review, that choice is weighted
heavily with performance and features of the VSD-XE that the competing products
simply cannot match in their current configurations. However, users requiring a
100+V/35A drive who do not need the features of the Granite product, and
are not gong to use step multipliers, would most likely be happy with the less
expensive previous winner, the Dugong from CNCdrives in Hungary.
In both performance and
features, of the products that were evaluated in this lineup, the Granite XE
has no equal. I have made the argument that for use with DC brush drives, the
significantly higher cost of the Granite XE is not justifiable since you would
be paying for capabilities (AC, Brushless, Stepper, etc. that you would not be
using. However, the cost of the XE in many cases can now be literally halved
for medium sized DC brush motors because the VSD can now handle two motors.
Previously, from a pure
performance standpoint, the best
showing came from the Viper and the Rutex, but problems or limitations
with each drive mitigated this advantage. When price, tuning software,
performance, support, and reliability were all considered together, the Dugong
was the leader, even though it may not
have been the best in every category. However, as with any review, it should be
remembered that the product’s performance is delivered under a specific time
frame and conditions, which is fluid and can change over time.
Between the original review
10 months ago and today, the Dugong has stagnated and retains its deficiencies,
Granite has continued development and added very significantly to their product
offering, cutting the effective cost in half for certain applications and
providing increased capacity and capability.
On performance alone,
the Granite XE is equal to the best drives in this lineup. When step
multipliers are used, the Granite significantly exceeds the previous winner;
the Dugong.
In features, it has
no equal in this lineup. In this group of products, of those that were
evaluated, the Granite VSD stands alone in having some of the features of the
mainstream industrial drives costing much more, so the XE is also the winner on
features.
On price, Granite has
leveled the playing field with their dual drive capability. Only the Gecko
remains less costly for two motors, but the Gecko has much smaller ratings, so
a direct comparison is not reasonable. When used to run two DC brush motors of
medium size, the Granite VSD-XE is competitively priced. Shipping remains
extremely expensive for those in the US, but I have checked this out and
Granite has no control over the extremely high cost. Those are the rates. Same
package is $14.00 from US to Finland, but $60 from Finland to the US. If 4
drives are purchased at the same time, the shipping remains the same and
becomes less of a disadvantage.
Reliability is unknown at
this point and will be covered with an update if the drive proves unreliable.
However, the drive has about every electrical protection one can think of and
the mistake that I made which killed the Whale drive would not have affected
the Granite XE. The VSD has overcurrent
protection that would eliminate the likely cause of the Rutex failures.
The manual’s advises to
limit the power during initial setup. I did this by placing a 3A ‘safety’ fuse
in the HV supply to the drive. Once the drive was functioning and the settings
ratcheted up to 10A cont 38A max, predictably the next step response test blew
the 3A fuse. My impatience led to putting in a new 30A fuse before the CAPs had
bled down fully, discharging the cap into the VSD drive. Certainly this blunder
has the potential to immediately fry many drives, but the XE came thru
unscathed.
Note that the VDS-XE was tested only with a single
large DC brush motor for this review.
AC motor, BLDC motor, Stepper motor and the dual DC brush motor
capability were not tested and no conclusion should be drawn from this review
about performance in those applications..
UPDATE:
06/24/2010: Despite Granite Devices website claim that they have a ‘zero tolerance’
policy for errors, the actual product has non-operation features and extreme
limitations that make tuning extremely difficult if not impossible because the
motors behave differently in use than they do with a single tiny jog and there
is no practical method to conveniently
test tuning setting made with the tuning software, making the tuning process a
very tedious and arduous process involving repeatedly unplugging and plugging
the cables.
Additionally,
Granite Devices has been claiming for months that their stepper drive firmware would
be out in ‘two weeks’ and it is still not released. They state that fixing the
tuning issue is ‘not a priority’ and that making the advertised fatures
actually work would be ‘a good idea for the next firmware release’.
While the
Granite VDS-XE has undisputable the best performance of any of the DC brush
drives in this review, I would not recommend it unless there is a specific
feature that is not only critical to the intended application, but that the
functionality of that feature can be confirmed in advance and made a condition
of the sale of the product.
Comments from the Vendors:
Tom Eldridge, from Rutex
tech support, provides this rationalization of why they do not supply the
special connector:
“I just want to
note that we do not expect customers to make the connector that you mentioned
you thought should have been supplied.” “I tell every customer who inquires about a drive
that I don't think already has a mother board to get one, and I also offer to
take it back after they are done using it for tuning. If I did not
mention this to you, it is because I assumed you already had a mother board.” Mr. Eldridge sums it up with this
statement; “ . . . . people make so
many mistakes trying to wire things, and then I have to support them and help
them find their own wiring mistakes. So...using the Rutex mother board is
the only smart way to go. That's why I don't supply the 16 pin
connector.”
Paul,
from Leadshine Tech support has this to say about the products inability to
reset.
“For the error clearing and reset problem, I think
most of the errors would rarely occur if all the components in a
system are best designed. Otherwise, the system should be redesigned if
errors always appear. So the ability to clear the error without
turning off the power is not so necessary for a well designed system.”
Larry Kenny, owner of Larken
provided these statements in response to this review. This is typical of his
tone.
“Thanks Mr
Simpson for the lovely review, after answering your 16 or more sarcastic and
rude emails, i finally said just return the drive which I then gave you your
Full money back. I'm not sure what
your issues are ,but no one deserves to be someones door mat just because he
sells them a servo drive.”
“Yes, i've sold hundreds of Viper 100/200, but the V75 is only been
available since 4 months. I have since fixed the T paramenter save bug which
you pointed out (thanks). As far as the delay in getting you the manual, I am a
single parent and loaded down with sales, r&d and taking care of my kids,
so yes, relentless, stubborn emails can be frustrating (most people don't argue
like you did).”
Balasz from CNCdrives
provided this response to the inability of the drive’s error line to properly
signal a standard 5V BOB:
“However, our
new BOB already includes the buffer and the error line on this BOB is connected
to an opto onboard. The new BOB will be priced also for hobbiist, so I think to
use it together with our drives will be the best and easiest solution.”
Tero Kontkanen from Granite Devices has this to say about the mission critical ‘ Target Reached’ function not working on the drive:
“ I believe you
would need value that states when servo is settled within given tolerance. Is
this correct? There is no such output (at least for now). Thanks for pointing
out this too. It sounds to be a good addition to the next firmware release.”
And in response
to my suggested possible solution of using a mechanical switch (as I had to do
with the Rutex drive) instead of constantly plugging and unplugging ribbon cables:
“Yes, you can place switches to CMD cable
lines but you'll need switches also for USB cable to prevent it from
interfering the lines in non-config mode. Our future drives will have separated
lines for both links so simultaneous use will be much easier possible.”
Send questions, corrections
or comments to steve@thecubestudio.com