View Full Version : Galil analog outputs working?

11-24-2008, 02:45 PM
I'm trying to get spindle speed control with a VFD through my Galil card. See this related thread also. http://cnczone.com/forums/showthread.php?t=68589

Right now, I can control spindle speed with a 0 - 10 volt signal directly from a speed pot to the VFD. But when I connect to a Galil analog out, no joy. (Too little VFD impedance???) I've tried both MOCMDE and AN6.

For my next trial, I connected a voltmeter to both of the above points and cannot get a reading either. Surely, Galil can drive a voltmeter.

I'm looking for suggestions on what to investigate next.


11-24-2008, 03:02 PM
Command a speed with no wire connected except the common and check the analogue signal MOCMDx to common, if you get a suitable reading, then connect the analogue out to the VFD input and see if the voltage collapses.

11-24-2008, 04:32 PM
what is the code you are using to try and produce voltage output?

Are you using galil smart terminal, a custom app? Not enough information
What hardware? "AN6" has no meaning. @AN[x] is used to read an analog input.

MOCMDE is a terminal description for wiring axis 5 but not code

11-24-2008, 04:46 PM
OK, I just took readings.

I've been in contact with the host software vendor, Camsoft, and they are not seeing any computer setup problems. But, be aware, I am only commanding Galil through the host. If you know of the direct Galil commands to set MOCMDE to a certain voltage, I should repeat this trial without the host software confounding the issue.

The host is set up to read the voltage at AN2 and then send the same level out MOCMDE.

My pot is varying voltage from 4.7 to 9.9 volts. With only a voltmeter, MOCMDE goes from 4.68 to 4.83 volts. With the VFD connected. I get 4.02 to 4.15 while moving the pot. The VFD runs at 40% speed the whole time.


11-24-2008, 05:00 PM
I use native Galil commands, It depends on how you want to control the VFD, If using a spindle motor in true velocity mode, you can set the axis' PID to zero, (it is not a servo axis) and use the FV command to develop voltage directly proportional to the commanded velocity. So, if you issue a JG, then the torque is not error-based, but an open-loop voltage.
I would think if you have software control to command a SP speed, you would not need a manual pot input?
If using a pot/analogue input, then you would need to scale it to the MOCMDx output.

11-24-2008, 05:11 PM
as AL said but before offering multiple solutions that may not be relevant, do you have encoder feedback on the drive or is it open loop?

11-24-2008, 05:23 PM
OK, Issued this after checking PID values were all 0
FV ,,,,10
JG 0,0,0,0,200000

and I got 4.02 volts connected to VFD. Galil reference under FV says I should get 2.44

JG ,,,,500000

still had 4.02 volts at MOCMDE

any comments?


11-24-2008, 06:35 PM
Try the OF command and see what you get.


11-24-2008, 07:29 PM
OK, I tried the OF commands. No response for voltage at MOCMDE.

It did make the Z axis servo start to shutter at high speed. Shook the whole damn machine. Scared me. Did a hard boot and problem went away.

So, is my galil card broke here?


11-24-2008, 07:36 PM
"any comments?"

so you have an encoder or not? the answer depends on your answer. you're dripfeeding information too slowly to get quality results.

11-24-2008, 07:51 PM
An OF command should only affect the axis it was sent to. So something is going on there.


11-24-2008, 08:23 PM
No encoder. He is trying to get an open loop analog output. It should be easy as I want 1 volt.


Now I want 2 volts


But that does not seem to be the case.


11-24-2008, 08:26 PM
"any comments?"

so you have an encoder or not? the answer depends on your answer. you're dripfeeding information too slowly to get quality results.

Sorry, I didn't answer you yet. I'm running the system open loop because the encoder is located on the spindle itself after the variable speed transmission (2J style milling head). The VFD is set up to run full speed at 10 volts, 1/2 speed at 5 volts, 0 at 0 volts.


11-24-2008, 09:26 PM
I just tried something on my Galil DMC.
Maybe your still in servo mode, you may need to turn the axis off then
use the offset.

MOE (motor off E)
OFE=0 (I got 10.09 volts)
OFE=1 (8.08 volts)
OFE=1.5 (7.07 v)
OFE=5 (0.02 v)
OFE=9 (-8.02 V)

SHE ('servo here E' should put it back into servo mode i.e. needs encoder)

This should work on yours, if not try another axis then you'll know E is fried.
Hope this helps.