Looking for a manual for a Physik Instrumente C-842.AP1 motor amplifier

[Dave_Thomson]

A client of ours has 8 Physik Instruments DC servo motors and 8 P.I. C-842.AP1 amplifiers. We are trying to upgrade the 15 year old system to new LabVIEW, and need specs on the amps. No one can find a manual. Even P.I. claims they do not have any customer documentation for these units. Does anyone out there have a manual they could share?

Thanks,

    DaveT

[Dave_Thomson]

One other issue that maybe someone can shed some light on:

The configuration on the old (W2K) computer was inadvertently lost, which is why we need the info for the C-842.AP1 amps, so we can reconfigure the motion hardware on the new computer. The vendor (PI) swears that the motors we have are DC servo motors. The only reference we can find to the C-842.AP1 amps say that they convert PWM signals to DC servo signals. But when we open up the connections box, we see that the wires going to the C-842.AP1's are the stepper signals (step/CW and direction/CCW). What a mix!

I can think of two possibilities: 1) the NI PXI-7344 card can somehow be configured to put PWM signals out on the stepper wires, or 2) the C-842.AP1 not only can convert PWM signals to DC servo signals, but it can also convert stepper signals to DC servo signals. I am tempted to discount #1, since nothing in the 7344 configuration indicates that the stepper pins can be configured to have PWM signals. (There are PWM outputs, but they are auxilliary digital lines, and the manual specifically states that they have nothing to do with the motor drive.) So I'm hoping that someone somewhere can confirm that the C-842.AP1 can accept stepper inputs as well as PWM inputs for conversion...

DaveT

[wiebe@CARYA]

That's weird, PI mentions the C-842 in several documents, but no manual is to be found. There are even articles about their LabVIEW (LabView ) drivers in their 1997 and 1999 newsletters. Some C-842 specs are in there as well.

The C-842 seems to be the same as the C-843, except that the C-842 is for ISA, not PCI. (Loosely based on this document)

This document has some specifications, they might help. Not sure what you're looking for.

It also mentions: "The [C-842] gear ratio is 29.6:1; See the C-842 Controller User Manual (MS 45E) for more details."... 

That seems to be this one:

https://static.physikinstrumente.com/fileadmin/user_upload/physik_instrumente/files/user_manuals/M-6...

This seems to be an excessive programming study: Studienarbeit-damm.

[RiWoMo]

Hi Dave,

The C-842.AP1 doesn't convert analog signals to PWM signals. It transforms a digital TTL PWM signal (pulse width / direction) into a 24V switched PWM-full-bridge output which is capable of driving the motor directly.
At the input side (male 15 pin D-SUB) you have pin 3 (PWMMAG) and pin 11 (PWMSIGN).
At the output side (female 15 pin D-SUB) the motor is connected to pin 2 (Motor+) and pin 9 (Motor-).

In addition to that you need a 24V power supply. All other pins of the 15 pin D-SUB can be looked up in the data sheet of the stage.

I hope this brings a little light into this issue.

Best regards

Richard

[Dave_Thomson]

Thanks for the info, Richard and weibe. These forums are amazing!

PI uses parts of their model numbers for various things, so the C-842 is not the same as the C-842.AP1. (They also have AP1 items that are completely different too!) In any case we're desperate for info on the C-842.AP1.

We do understand that the C-842.AP1 does not convert analog to PWM. It converts PWM to analog. What we need to know is whether it also can convert stepper signals to analog. (Conceptually, it could work. The PWM signals encode velocity as duty cycle. Stepper signals encode velocity as frequency. So it wouldn't be hard to create an amp that could do either one.)

The issue is that the stepper outputs of the 7344 are connected to the C-842.AP1. But as far as we can tell, the 7344 can't put out PWM motor control.

In any case, the pin numbers you mention for the PWM signals will be useful for us to check. Thanks!

Do you have the full pin-out info for the C-842.AP1 15pin connector? We do have the motor manual, and that has the pinout for the 15pin D connector on the output of the am (input to the motor), but we don't know the pinout for the input side of the amp.

Thanks,

      DaveT

[Dave_Thomson]

Richard - We have developed a theory for how this system used to work. The assumptions are:
1) The motor is DC servo.

2) The amp is PWM input, DC Servo output.

3) The NI card is Stepper output.

Nowhere in the old code do they set a velocity. So the velocity is some default, probably set in MAX.

If the Velocity of stepper pulses was set to the PWM frequency, then the system would always run at a fixed velocity. The PWM will be 50% duty cycle all the time. The PWM direction should be compatible with Stepper Direction.

The Encoder feedback allows it all to work. They move the stage at a constant velocity until the encoder says it got there.

So, for this all to work, we just need to know what the PWM frequency is for that amp.

Could you tell us that?

Thanks again,

      DaveT

[Dave_Thomson]

Just in case it is worthwhile as an archive, here's some more to the story:
The motors are DC servos.

The amps are PWM in, DC out.

The NI card is stepper, as it comes from the factory.

The trick is that the NI card had custom FPGA code in it that enabled it to put out PWM signals on the stepper lines! We assume (but haven't yet verified) that Physik Instrumente created this custom code.

We also assume that this code may not be maintainable or usable with the new versions of MAX and the card firmware... Ugh...

Also - we just found this post that actually describes the FPGA firmware option. And makes it look like this WAS an NI deal, not from PI...

https://forums.ni.com/t5/LabVIEW/PWM-Update-Rate-using-PXI-7334-6602-cards/td-p/84020

We still don't have any info on how to configure the steps or servo settings when using the card in PWM mode. There's a readme file in that link, but no config instructions...