[Brian L]

I an having some following error issues with my '92 Partner 4 with Centurion V control. Following error runs exactly the same value plus and minus up to about 70 ipm, then when I step up to 80 ipm, it goes running off in only the minus feed directions, i.e. X minus, Y minus and Z minus... the plus directions all stay around the .050" level while the other direction climbs until it faults out the drive at .250".

We were just working with the balance and signal pots of the Fenner drives and I found out about some set up procedures for the cards, where you check ohms resistance and voltages at certain points, so now I will check all of that first.

That got me to wondering if there was the same sort of procedure for the Acroloop cards, so if anybody knows of a process where I can make sure they are set correctly, I'm all ears.....

Right now the machine is running, but I have to have my rapids set under about 70 ipm and such or the drives fault.

[Al_The_Man]

Is this something that suddenly appeared? If so I would look to addressing the reason before retuning anything.
Are you saying that the drives go in to runaway condition at a certain feed rate?
If the drives have an option of mode, typically they would be set to Torque mode of operation.
Al.

[Brian L]

Hi Al,

No, it's not running away, it's faulting the servos at anything over say 80ipm and shutting down the machine because of a following error fault. As for suddenly appearing, no not really, this machine had been sitting for at least 3 years, maybe longer in some guy's garage with no power, I got it, replaced the motherboard and made some modifications as we couldn't get the old motherboard to boot up.

The machine has had the following error issue since I powered it up.... I just went in and set my parameters for rapids at 60 ipm and keep my feed rates under that also. But, obviously something is out of whack, and I'd like to track it down and figure it out, so the machine can be operated as it should be. I am no electrical guru by any stretch, but have a friend who is helping with the electronics end, and with help from this board, I've gotten pretty far with the machine.... just wanted to know if there was some form of tuning needed on the acroloop cards.

My limited electrical knowledge indicates to me that because the following error has issue in the same direction for each axis, checks perfect below a feedrate of 60ipm or so on each, and then goes whacky above that point in each.... makes me think that there is some component that is failing or out of adjustment.... that is effecting each axis drive.... but then again, I'm pretty uneducated on electronics.... so I'm guessing....

[Brian L]

Here is a video I shot yesterday, basically just the screen as we ran back and forth 5".... but it shows how the following error is stable in one direction, then goes climbing in the other.

Following error screen on Milltronics - YouTube

[Al_The_Man]

Its been a while, I will see if I can dig out my Acroloop manuals tomorrow.
Al.

[darrengladysz]

I may be wrong with this but in the config on acrocut or acromill there is a setting to turn off the machine if the following error exceeds a certain value. Can it be that your machine's servo's can not keep up and then acroloop turns off?

If I recall it is either f8 or f7 for settings to check this out.

Here is a link to the product literature:

http://www.parkermotion.com/manuals/Acroloop/ACR.htm

You can also download acrview (I don't know if your board supports this) to tune your servo, here is the link:

http://www.parkermotion.com/support_samples.htm

Let me know if this helps.

Thanks

Darren

[Brian L]

Yes, the machine shuts down if the following error hits .250", that's a parameter that can be set for each axis. As for why, I don't know, there seems to be no difference mechanically for any of the screws as to which direction I go, i.e. the same amount of force is required to turn for either direction, and there appear to be no tight spots, or anything like that. And the fact that they keep up in one direction with no issue seems to state that the servos can keep up. I was able, before I set the rapids to 60 ipm in the parameters, to rapid at 300 ipm in the positive directions only, so I don't suspect it's anything mechanical in nature.

Thanks for the links to the information, will have to decipher which might apply and see what I can figure out.

[Al_The_Man]

Are you running a version of Acrocut or Acromill? or is this third party software?
In the Acroloop manuals there is a section Tuning the Servo PID loop and Acroloop has an internal scope display in the Diagnostic screen for watching the tuning results.
Also in the Acromill/Acrocut manual there is a flow chart of function for the different menu's, selection and F8 of the set/diag sets the parameters also.
It is also important to set the drives to the recommended mode, as a rule, drive are set to the Torque (current) mode of operation, you may want to see if the Fenner drives have this option.
If the problem is not mechanical and the drives/motors are sized right, then usually the symptom that produces following error is in the PID & drive tuning.
Al.

[Brian L]

Al,

This is getting way over my head, but to answer what I can....

Acrocut or Acromill, I dunno, where/how would I find out? When the computer boots up I see "Acroloop XYZ" for a moment, and I checked my Main-Util-Info page and it shows "Centurion V CNc 1.29.09" and then below that after memory info, it states "Controller card v0206 0000" and below that I have:

X axis Acroloop v0208 0000 0100 0000
Y axis Acroloop v0208 0000 0200 0000
Z axis Acroloop v0208 0000 0000 0000

Beyond that info, I was able to take a card out, the X axis card, it has these numbers across it:

6-07-004-010 PC-ARCON-02

On the chip side of the card, I have stickers on some of the chips, one says

ACRO U9
C5B5
VER 2.08

Then stickers right on the board with

SN 158
REV A
92 13

I don't know if any of that answers any questions....

[Al_The_Man]

The Acroloop XYZ at boot up appears to confirm that it is Acroloop s/w, but I don't recognize the screen in your Utube video?
Are you running under Windows or DOS?
If it is anything like the software I am familiar with, there should be on screen function keys that you can drill down to the Tuning menu?
I attended the Acroloop training class when the ACR8000 first came out, but that was many moons ago.
Al.

[Brian L]

Running under DOS, that screen was just the normal run screen with the display set for following error. If you want to see more screen shots, this is my photobucket folder for the mill, quite a few screen shots scattered throughout:

Milltronic pictures by dmogbrian - Photobucket

[Al_The_Man]

I don't recognize any of those screens? I suspect that they use their own custom s/w.
I would expect a set up menu for the tuning, PID etc?
Is there any manuals on the system?
Al.

[Brian L]

I have Milltronics manuals, but nothing for the Acroloop stuff. I thought these screens are/were pretty standard across the Milltronics system. If you mean there should be "Acroloop" Software screens, I wouldn't know, and more so, if they are there, how to access them. Like I said, this is getting deeper than my knowledge of electronics by far.

[70cyclone]

if you swap servo drive cards does the problem change to the other axis or stay where it is now?

[Brian L]

It is on all three axis now..... and which cards/what would you swap? The acroloop cards in the computer case, the X card is different than the Y and Z, has extra connections. If you mean the actual servo drives, the Fenner components, then I could see changing those out from axis to axis.....

[Al_The_Man]

It sounds like you have the Fenner drives that are virtually the same for Servo Dynamics and Westamp, if they sit in a card cage together.
I have the manuals for the Fenner/SD manual which is virtually the same for the Westamps.
If you need a copy send me PM with an email address, it shows how to wire up a battery box into the analogue input for testing.
These drives were prone to components changing with age and usually the expedient way when this happened was to replace the drives with more modern Advanced Motion models and set up in the torque mode of operation, also in this mode,the tach input is no longer required.
Al.

[Brian L]

Yes, I have Fenner (Servo Dynamics it also says on the manual) drives, pretty sure they are the SDF 1220-17 units and I found a manual on the web for those. Here is what the insides of the machine look like:

The servo drives are lower right, below the blue caps



The acroloop cards are inside the black computer box located upper left. the inside of that looks like this, sorry the picture is rotated, the Acroloop cards would be the three with the ribbon cables along the spines:



I will send a pm for the manual in case it is something different than I have....

[Marty_Escarcega]

To all, with the help of ZZZZ we finally solved Brian's following error problems. The early Servo Dynamics amplifiers required a +15/-15VDC power supply input. We had finally found that the -15VDC regulator went bad and was outputting -24VDC. Which explains why the following error was the same direction on all three axis. I felt it was important to let everyone know the outcome, incase it ever happens to someone else. Basics first, check all your voltages.

Our thanks to ZZZZ for all his help!
Marty

[Brian L]

Not only thanks to ZZZZ, but many thanks to Marty for sticking in there with me and figuring it out. I wouldn't have the machine back running healthy if it wasn't for help from everybody.

Now if I can get the shop above freezing (uncommonly cold weather for Arizona) I can actually get some work done.