[MrMetric]

I have one VSD-E 160V drive and two VSD-E 80V drives that I'm using for a Hurco KMB-1 machine retrofit. The servos are brush type. Sadly, I've had nothing but trouble. I have been having issues trying to tune one the 80V drives (first attempt), to the point where I've wondered if I have something wrong. So, I decided to move to the 160V drive. However, I cannot get *any* encoder response on that drive at all. It always shows up as '0'. I have a motor on the ground so that I don't have to worry about runaway situations, and I can manually move the shaft. I don't have any high voltage power on , atlhough when I did, I still didn't have any encoder change.

I know the wiring is correct because I can simply move the encoder from the 160 to 80V amps and then then I see encoder action. So... wiring is fine.... Any ideas?

Thanks.

[on edit: I'm loading the same configuration for both the 80V and 160V, so the issue shouldn't be one of setup I don't think. Plus, I don't see anything in the DCTool that allows one to enable or disable the encoder monitoring)

[Montabelli]

what kind of encoder are you running? what is its power requirement?

[MrMetric]

Good Question but...

Nothing special really.... It is a US Digital lower cost encoder that runs single ended and on 5VDC. The power is fine and I can see the quadrature output properly toggling on. Power is being fed to the encoder from the VSD-E and, as I said, the exact same encoder/cable is working fine on the 80V VSD amp.

Alan

[Montabelli]

I would be looking for compatibility issues with the then encoder or something amiss in the wiring of the encoder.

[MrMetric]

It definitely isn't wiring of the encoder because the same exact wire and encoder provides count feedback with the 80V version (I just moved the wire over from the other amp). That also negates the compatibility question, or should. I haven't seen any specs that differ for encoders between the 80V and 160V amps. The latter is just an upgrade of the former so the pinouts on the amps should also be the same (although, in fairness, I need to verify that, which I will do shortly). The encoder is pretty generic. It is just a 5VDC unit, which the amp regulates down from the 12VDC input it gets. After that, there isn't much to an encoder. It either provides single ended or differential outputs, both of which the amp supports. But you have given me something to confirm. The encoders should be connected to the (+) input and I should verify that is the case. It is unlikely, but possible, that the 80V and 160V models would behave differently if, say, someone (me) had screwed up and had the encoder signals connected to the (-) inputs.

[Tkamsker]

I just did an retrofit on a bridgeport 412 which also has brush servos .. i am on vacation right nnow so i recall ..
There is at the config tuning manual some req about encoders and for test try an quadrature hand encoder and see if you see some thing in the config menue you should see minimum some counts if not try the amt104 encoder they worked ..

[MrMetric]

Hi TKamster,
Yep, that is exactly what I am trying. The screen you are talking about is the second tab of the DCTool Status. It shows the encoder counts. When I'm hooked up to the 80V amp, I can spin the shaft and see the encoder counting (spin it very slowly and I can see the increment or decrement). When I hook *the same encoder, wiring harness, etc) to the 160V guy, I don't see any counting action going on (although if I monitor the encoder with a scope, I can definitely see the toggling there). The count is rock solid at 0. :-( Obviously this leads to an error while tuning the amp because there is no feedback. I don't actually see much in the manual that would cause the amp to not "see" the pulses that are clearly there (on the scope). The setup I'm using is the same as the 80V amp, so scaling (the only thing I can see that could cause a problem) is the same on both amps... plus, I've confirmed that there are legitimate scaling values (although nothing has been tuned so I cannot say any of the params are correct).

Alan

[Tkamsker]

You know i sit now in the middle of the alps but ...
I would note the main params of the 80v and start from scrstch a new config ...

[MrMetric]

Tkamster,
That isn't any fun.... I'm sitting in a sun filled California but the idea of looking over a mountains or a lake is far more appealing! :-) Anyhow, I have, in effect, done that but I shall try again. There isn't a whole lot of room for error there though. When I connect to the drive, I import the existing parameters from the 160V unit. There aren't many things that pertain to encoder setup and I've tried to change those minutely, saved, and then reimported, just to confirm that the settings are "real." They appear to be. So, I feel like I'm still at stage 1 and a tad frustrated. I do have one more 80V drive, however, so I think I'll power that up and see if the counts are working there. I'm not sure what it will tell me, but at least I'll have consistent behavior amongst the 80V units.

Alan

[MrMetric]

Well, instead of 'Sleepless in Seattle' it is 'Frustrated in Sunnyvale'...

There is some more to this. Let me explain how I'm powering the drives... I have a computer in my system that, of course, has a power supply. I get my 5V and 12V from that supply. Now, I would *assume* that the power there is very clean. The computer controls a low voltage (opto-isolated) relay that then energizes a contactor that provides 220VAC to a transformer, that provides power, through a rectifier and capacitor (to obtain about 56VDC, as I recall) to the HV side of the servo amps.

So, why is this germane? Well, I'm not totally sure... But I've noticed one thing that is very frustrating to me. I lose GDTool connectivity to my drives *very* easily. But the most interesting thing is that it isn't necessarily during an event that would cause a great deal of noise (such as turning on the HV power). For instance, I can connect to the drive and after I power on the HV side, I will correctly get a single blue LED constantly lit. But while trying to get the encoder working on my third drive (second 80V VSD-E), as soon as I try to do something as inane as 'upload configuration', I'll often end up with a communications error. And this is happening almost all the time when I try to do a tuning session with this other drive.

So, in summary, I have three drives and each of them has a different problem it seems... What the heck is going on? Is my FTDI cable lousy? Are the drives unreliable? I'm just not sure anymore. I never had these issues with my old analog Westamp drives. I dearly want these Granite VSD-E drives to work, but right now they are driving me crazy. I am willing to bet that this is probably all me but.... I'm frustrated.

Alan

[Montabelli]

if you have an old computer powersupply that is available, try using it for all your logic power. that way you don't have to worry about windows doing something weird to your power. I assume dc tools is the version of the gdtools for the double drive dc setup, It should have some capacity to issue direct commands to the motors on the drive, if not there must be some way to do it from gdtools

[MrMetric]

Yes, I agree.... I'm been thinking of putting a different 12VDC power supply in there for temporary testing, in nothing else. However, windows shouldn't be able to do anything to the power outside of turning it on or off. Anyhow, even though I don't see that it will make much of a difference, at this point I see no reason not to try.

Oh, sorry about the DCTools. I use something call that sometimes but in this case when I say DCTools, I mean GDTool, the Granite Devices configuration and tuning software.

[Tkamsker]

I always have extra Logic voltage ,.. And i use an Laptop to connect to the Board probably i was Lucky ,..

[MrMetric]

I hooked up a completely independent linear power supply but the results are pretty much the same....

I'm beginning to think you were either lucky or I am very unlucky.... I can't seem to get anything to work, period. I'm also starting to wonder if either the documentation is lacking or the GDTool application is just very buggy. For instance, I've started to see a pattern with all three boards. If I am connected and have HV connected, I almost always have a single blue light indicating everything is ready. But if I don't do *anything* but execute a "reset drive" command, I end up with a communications error. OK, that *may* make sense, but you would think that if the expected result was that you would have to shut down the power again and go through a whole sync process with the USB, that a dialog would show up telling you this. I mean, at this point I'm wondering if this strange behavior is expected or indicative of my drive not working.

On my third drive, the strange thing is that I can command a step test and although I get a graph showing a commanded position, the drive never moves (and the actual position is, as expected, flat line at 0). I *know* my motor is wired properly because I can use a 12VDC battery to creep the axis. And I know the encoder is correct because, on that axis, I can see the counts.

So, I'm three drives dead, two with similar problems, one different and seemingly getting nowhere. I think the Granite drives look great on paper but I'm not sure there are enough out there to form a critical mass for effective community support. At this point I'm hoping the manufacturer can come to the rescue but so far Tero hasn't responded to this thread. I dearly want the Granites to work, but I'm quickly wondering if that is going to happen. <sniff, sniff>

This is my summary...
either a bad USB setup cable
3 bad drives
flaky software
user error

I hope it is the last.

[Tkamsker]

I have 3 Granite working Fine and in Winter i do a dual Drive setup for axis 4 & 5 for a trunnion setup so i Hope I get more luck ,..

[Montabelli]

what happened when you did your tuning with the gd tool? did you get some motion and charts of the responce of the motor? also what are your pid values? what is your scale set to? are you running step and direction or analog?

[MrMetric]

All very good questions. I moved into a scattered mode of testing to see if I could isolate my issues with a particular drive and, in the end, have become more confused because the results are worse with the other drives. Once there is consistent support from someone (if you are volunteering, then that is fantastic! ) then it would make sense to concentrate on one tuning one axis, one drive. In the interim, I'll do my best to describe... Please note that all drive combinations are connected either the same actual axis motor/encoder or a motor/encoder that is sitting on a bench. In other words, I'm moving the cables from one drive to the other...

Drive 1 (80V): GDTool resulted in oscillations on the axis. I making changes really didn't quell these oscillations. I tried all three modes but nothing seemed to work. Input is set to SPI mode for the time being, but will eventually be analog. PID values I'll have to get

Drive 2 (160V): Attempts to perform the tuning session are not successful. I end up with either a position or following error very quickly. While investigating this, I noticed that the encoder count never changes when I rotate the shaft. I verified that the encoder is working, however, with a scope. Input mode is set to SPI but, again, will eventually change to analog. PID values seem useless here until I can get the encoder to be successfully read by the drive (and shown on GDTool).

Drive 3 (80V): When I try tuning in any of the three modes, I see no movement in the motor at all and this is also reflected in the flat line of the 'actual position' on the graph. SPI mode, and will have to get the PID values.

On *all* drives, I've noticed that I can sync GDTool, apply HV power, confirm that I have a single BLUE LED lit constantly (indicating everything is OK), and when I select 'Reset Drive' within GDTool, I lose communication with the VSD drive. The only way I can regain it is to cycle the logic power (and, of course, I also turn off the HV while doing this).

Originally I was using the 12VDC from the computer as my source of power to the VSD drives. I have since (temporarily) changed this to a completely separate linear power supply. This has not appreciably changed any of the results (i.e. I haven't noticed any difference).

If there is a specific set of tests I can perform, I welcome the support!

[Montabelli]

ok, what are you using as your controller, I assume since you are going to run analog it is not mach3. I suggest you se up and tune your motors, pick one and only one, and try and get a decent tune on it set your scale with GD Tool in your drive to 50/50, with just your usb cable connected follow the tuning sequence play with your pid settings and plot out your results to get the best results in torque mode, then go to the command section and see if you are able to tell it to move and get the proper response. if you are turning the motor shaft and the encoder count does not change with the high voltage off and logged in to the drive, for what ever reason it is not getting the signal. I have only used these drives to run ac servos, so my dc experience is not with zsd drives.

[MrMetric]

Yes, I agree. Bouncing around like a frenetic ping pong ball isn't effective. It was useful before just to see if I can identify any single fault, but concentrating on a single thing is probably best. So, I'll go back to the 80V drive I started with because at least that appears to have the ability to read the encoder and when I attach it to a motor, it actually moves the motor (what a novel concept). So, henceforth, I'll limit my discussion to that until further notice.

You are correct, I am not using Mach3. This will be a LinuxCNC build although at this point it is sort of academic because I am hooking a windows PC directly up to the VSD drive through the USB cable. So, no Mesa board, no Linux machine, nothing.

I will try 50/50 and report on that.

Thank you for helping!
Alan

[MrMetric]

OK. I am working with the 80V drive. Here is what I found...

Setup:
Motor Settings
Type: Brush DC
Motor pole count: 2
Max Peak current: 11490mA
Max continuous current: 10500mA
Current fault limit: 18500mA
Encoder resolution: 1000PPR
Motor Thermal Constant: 1580s
Invert encoder direction: NO (not checked)
Use Hall sensors: NO (not checked)

General Settings:
Motor control mode: Torque Mode
Drive pluse input mode: None/Indexer
Input filter: NO (not checked)
Limits: Motion fault Limit: 0
HV voltage upper limit: 90000mV
HV voltage lower limit: 20000mV

Trajectory planner:
Acceleration limit: 5
Velocity limit: 12000
Error recovery velocity limit: 200
Input scaling:
Multiplier: 50
Divider: 50
all other values were greyed out and therefore not reported.

Torque Tuning:
Torque P gain: 4000
Torque I gain: 200
Torque low pass filter: 1000Hz

Results:
The chart looks amazingly good with nominal difference between the torque target and the torque achieved. However, I'm perplexed by the fact that the axis doesn't move at all during this test. Is that correct? Perhaps I have a fundamental misconception about what we are trying to accomplish here. When I add the 'position target', it is flat line at 0, so clearly there is no commanded position. But, again, the chart looks good! Before we go on to the next tuning, I wanted to get some feedback on just what we did (even though it appears to be good).

Here are some other things I noticed... First, my voltage is a tad high still. I hooked my scope up to the HV line and I have about 2Vpp of noise with a Vmax of about 81 volts. I think I need to remove another coil on the secondary of the transformer. The 12VDC is riding at about 12.3V, which is fine.

One thing that was *very* odd is that I took a peak at the encoder count while I was in torque mode and it was moving wildly. I mean, zipping between things like -13000 and +1800. Oddly, when I tried Velocity Mode, the encoder was stable... Is this significant? I was not expecting the mode to alter whether or not GDTool would display the count properly but I've also come to question how buggy GDTool may be. It is possible that the behavior I observed is regrettable but not unexpected (?).

I wasn't sure what I should try to tune next so I just tinkered a bit. I tried Velocity Mode becasue it was the next in the General Setting list. I am waaaay off on tuning there and am hoping someone can give me a good "starting point". I did notice that my axis did seem to jog only one direction, though, so I'll probably have to put a battery on there to move it back before I do too much more testing. On the chart I see a step up and then a step down for the command velocity. The achieved looks like 60% of a *very* noisy sine way (hence the axis is probably moving over dominantly in one direction) and with about a 0.07s lag from the commanded velocity.

Montabelli.... You said "then go to the command section and see if you are able to tell it to move and get the proper response"... Can you describe this a bit? The GDTool manuals don't really describe how you can command a position. The only place I see to enter anything like this would be in the Event Log area but the SPI command is not something I see anything discussed.

One other very strange thing.... I seem to go through these episodes of sheer frustration wherein my connection to the VSD is very very flaky. GDTool will lose sync and I'll have to go through a complete power cycle to get it connected again... only to lose sync again. Grrr. Another bit of the mystery is that I will set the drive to, say, Torque Mode and then I'll do a 'import drive settings'.... Still in Torque Mode (good). But then GDTool will lose its connection and after I reestablish it, and reimport the current settings, suddenly the drive is in Velocity Mode. I'm not sure *what* the issue is. Bad computer, bad drive, bad FTDI-USB adapter? I don't think there is *that* much noise in the system to cause these issues... Argh!

Alan