CMC/EG&G brushless amplifier help

[knightlord]

Hi
I picked up 4 CMC (cleveland machine controls) brushless amplifiers, power supply, and motors off ebay the other day.
my problem is trying to get them going
the amplifier model is BLA 2412
I can get the enable light to light up and the servo holds position when I try to turn the shaft, I just dont know what pin is the voltage input (should have a +/- 10v input somewhere)
I know that command pin 3 and 5 have +12volts and control pin 1 has +12v
I can put 12v to pin 6 and the drive enables.
does anyone know anything about these amps or ones that are similar?
im really looking for a description for the connectors input/outputs so I can get the drives going the way they should be

thanks

[Al_The_Man]

I saw these on ebay and at that time could not find anything, you may have to try contacting CMC and see if they will send you a data sheet, it is possibly because it is a Legacy product.
Al.

[knightlord]

thanks for the quick response
I emailed cmc and the only thing they have is like a brochure, I looked through it, had specs but no descriptions on what each connector pin does

does anyone have a amplifier like this one, even if it is close, I could try it.

thanks

[Al_The_Man]

It might be worth a quick call to CMC and ask for technical assistance, you may get someone that can give you the info over the phone, It has worked for me in the past, as all you may get by emailing is the sales dept.
Al.

[knightlord]

I wasnt able to get anymore information from cmc, so I just started playing around
found out that the top two connectors on the command connector are the +/- ref inputs, I think they might be +/- 12v not 10v but it still works with 10

I picked up two pixie p100's and hooked them up, I can get the drives running with mach 3 but I keep getting following errors, I set the following error to its maximum and if I get over say 2k rpm, they error. I can get the drives up to around 6k with my powersupply hooked up to the +/- inputs.
I have toned the drives and it looks like the one in the manual, nice slop with almost no overshoot. I have been playing with the dip switch on it but havent been able to get it to work the way it should.

its hard to get help when no one has drives like these and havent been able to find someone with these to ask for a manual or help.

[Al_The_Man]

If they are anything like AMC drives, there is a few ways they can be operated in. Current mode (prefered) Velocity mode, or Tach mode where they expect either a DC tach or digital tach in the form of encoder signals.
I am really suprised that CMC do not have any info on them, I'll bet someone in the Technical dept. does. If only you could get the right guy.
Al.

[knightlord]

wow, that was quick

I can put it in velocity or torque mode It think

in one option I cant turn the motor shafts, it tryes to stay in position
the other I think it torque, I can turn the shaft but when I hook it up to the pixie, I cant hold the shaft.

maybe I will have to try again to get an answer from cmc, the servos are from 1992, its a while ago, but you would think they would still have some info

the motors seem to run good at low rpms under 1k, they have a little studder when getting up to speed, kinda like its overshooting then slowing down, does this about 3 times when getting to speed.
the encoders are 1250 cpr or 5000 pulses per rev, could they be to high for pixie? even though there site says any cpr?

thanks

[KTP]

Any idea what count the encoders are? The Pixie P100 can accept very high step rates, but Mach3 can only generate 45khz or so. You can set the Pixie to multiply the incoming steps if you desire higher speeds than Mach3 can generate. I am assuming your amp is set in current mode, and the voltage range is +/-10V on the ref +/- pins.

You can use the Pixie to internally generate steps to test the motor/amplifier speeds by setting the #22 run continuous freq. to the steps per second you want and then hit "C" and the motor should run at that step frequency.



Pixie P100 data sheet:
http://www.skyko.com/datasheets/SKY-P100.pdf

[knightlord]

the encoders are 5000 pulses per rev or 1250 cpr, I have the pixie multiplier set to 10 so I can get the higher speed since I dont have the purchased mach yet so I am limited to 25khz
I can get the motor to run while in the pixie putting out the steps using the c command, its just it gets to much following error when I use it with mach
I can put the accelleration to the slowest or fasteset or in between but it doesnt help as much as I want it to. right now to get up to around 2k I have the slowest acceleration set and the highest following error set

thanks

[KTP]

The Pixie quadrature encoder interface can handle in excess of 1.5 million quadrature encoder counts per second.

So for your 5000 count (in quadrature) encoders, that would be 300 motor revs per second, or 18,000 RPM. Probably your motors will not go that fast

I don't quite know what you mean by stutter when the motor is ramping up to speed. I certainly have not seen that in any of the brushless motors I have tried with the Pixie P100. Possibly your tuning is way off? If you want, upload to files or email a screenshot of your tuning graph.

[KTP]

By the way, even with step muliply set to a pretty high value like x10, you are still only going to get 250,000 steps per second with the free version of Mach3. With 5000 count in quadrature encoders, that would limit your top end speed to 3000 rpm. Just FYI

[Al_The_Man]

the encoders are 5000 pulses per rev or 1250 cpr,

That will be 1250 quadrature pulses/rev which results in quadrature x 4 = 5000 resolution.
Al.