Using 7i43 with Advanced Motion Control 30A8T

[acondit]

I picked up some used Advanced Motion Control 30A8T Controllers (Brush Type PWM Servo Amplifier). They require a +-10v analog signal.

Has anyone used these?

Is there a simple circuit to convert PWM/Dir to +-10v output?

Or am I better off just biting the bullet for a Mesa 7i33TA Quad analog servo amp interface?

Thanks,
Alan

[Al_The_Man]

I have used A-M-C extensively but only with ±10vdc.
There was someone here some time ago offering a PWM to analogue convertor, not sure if they are still around.
But these amps are not very useful for Mach as the drive needs to close the loop, which the A-M-C. do not, they are for controller closed loop systems.
Al.

[acondit]

I use EMC2 which closes the loop so that is not a problem.

[Al_The_Man]

So you should be able to use ±10vdc, no?
Al.

[acondit]

Yes, but I don't currently have anything to generate +-10v, while I do have something to generate PWM/Dir. Hence the questions:
Is there a simple circuit to convert PWM/Dir to +-10v output?

Or am I better off just biting the bullet for a Mesa 7i33TA Quad analog servo amp interface?

[Iron-Man]

Originally Posted by acondit Yes, but I don't currently have anything to generate +-10v, while I do have something to generate PWM/Dir. Hence the questions: Is there a simple circuit to convert PWM/Dir to +-10v output? Or am I better off just biting the bullet for a Mesa 7i33TA Quad analog servo amp interface?

acondit

I will also be using MESA cards. Currently working on several projects. Here is a link to Elmo motion control for a proven circuit to convert PWM-DIR to +- 10V analog. Here is the direct link:
http://www.elmomc.com/applications/a...with-a-PWM.pdf

You will still need to close the loop with encoders in EMC.

Hope this helps,

Iron-Man

[acondit]

Thanks for the link. That is what I have been looking for.

I have a 7i43 and two 7i42TA daughter cards to which I can wire the encoders. I may go ahead and build one of these to try it out. I suspect given the parts count that buying the 7i33TA may be cheaper in the long run, since it will do the DA conversion for 4 servos. Then I could save one of the 7i42TAs for my next machine controller.

Alan

[samco]

there is also the 7i48 that does 6 axis analog. (I am using both the 7i33 and the 7i48 in my machine) (2 5i20 fpga cards)

sam

[Iron-Man]

Has anyone used this ( 5i25) card? I am still undecided on the 5i20 or wait for the 5i25.

Iron-Man

[acondit]

OK, I have another question. It appears from the manual for the 30A8T that it expects 0 to +10v on one pin and -10v to 0 on another pin. The 7i33 and 7i48 have a single output pin for each amp that swings from -10v to +10v.

How do you connect the 30A8T to the 7i33 or 7i48???

Alan

[Al_The_Man]

The 30A8 only requires two connections which strictly speaking are differential +- but if you have two conductor single ended the common goes to -ref pin and the + to the +ref pin.
Your controller card should alternate polarity to alternate motor direction.
Your 7i card should have a common to the ±10vdc signal.
Al.

[acondit]

Thanks Al,

OK, on the 30A8T
Pin 1 is +10v/3mA output
Pin 2 is signal gnd
Pin 3 is -10v/3mA output
Pin 4 is +15v(max) +Ref Input
Pin 5 is -15v(max) -Ref Input

Lets just take the connections for one servo and see if I have it correct:
The first three pins from the 30A8T are an anemic power supply.
You are saying that I connect the +/-10v signal from the 7i48 pin10 AOUT0 to 30A8T pin4 +RefIn.
Then connect the 7i48 pin11 gnd to 30A8T pin5 -RefIn.

Is that correct?

I edited this to attach the schematic for the 30A8T to show the input connections for it.

Alan