7i76 +/-10V spindle output (-10v to +10v spindle output)

More
10 Oct 2017 23:21 #100179 by andypugh
[quote="pippin88" post=100036I see from the 7i76 manual, that is it possible to set it up in 'bipolar' mode for spindle output, to give out -5 to +5v. Is there any way to get +/-10v?[/quote]

Is it possible to set up the drive to give the speed you want at 5V rather than 10V?

Please Log in or Create an account to join the conversation.

More
15 Oct 2017 10:40 #100381 by pippin88
Thanks for the help, I now have this working (partly).

Omron G6S-2F 12V relay - DPDT relay
Wiring:
SPINDIR+ = 12V
SPINDIR- = Relay coil +
Flyback diode across relay coil

One pole of relay has:
NC - SPINDLEOUT
NO - Ground

Other pole has
NC - Ground
NO - SPINDLEOUT

Relay outputs are connected to Copley 422 amplifier REF+ and REF-



Problem at the moment is that forward works at the correct speed, but reverse does not get to full speed. I'm sure this is a software problem, as when I invert the SPINDIR in HAL, reverse works at full speed and forward does not get to full speed, therefore it isn't a motor / amplifier problem.
Attachments:

Please Log in or Create an account to join the conversation.

More
16 Oct 2017 10:11 #100428 by pippin88
I was incorrect about it being a software problem. Inverting SPINDIR did not actually result in full reverse speed - just full "reverse" speed in software (when I had infact changed forward and reverse by inverting SPINDIR...)

I have tracked the problem further, it appears to be due to single ended signal into the differential input on the drive.

Measured at the servo amplifier input:
REF+ grounded, and REF- supplied 10V results in full speed
REF+ supplied 10V, and REF- grounded results in about 800rpm which then drops to about 700rpm.

Please Log in or Create an account to join the conversation.

More
16 Oct 2017 12:03 #100430 by andypugh
That's interesting.
Are you using motion.spindle-speed-out-abs, or do you have a negative duty cycle command to the 7i76 in reverse?

Please Log in or Create an account to join the conversation.

More
16 Oct 2017 14:51 #100435 by PCW
If swapping the REF+ and REF- pins doesn't result in a equal and opposite
speed, it means they are not truly differential inputs

You should still be able to do this but it requires a floating power supply (Wall Wart?)
so you can swap spinout and spin- instead of REF+ and REF-

Please Log in or Create an account to join the conversation.

More
16 Oct 2017 14:55 #100436 by andypugh
Or, you could just live with reduced speed in reverse.

I hardy ever use any of my machines in reverse, and you won't be rigid-tapping at full speed.

Please Log in or Create an account to join the conversation.

More
18 Oct 2017 03:51 - 18 Oct 2017 03:52 #100501 by pippin88
Peter and Andy,

I am using motion.spindle-speed-out-abs

I found a application note from Galil about connecting their motion controller to a Copley amplifier (attached). It refers to a more modern Copley amplifier, but I suspect it may still be relevant.
It instructes: "The single ended +/-10V analog output (MOCMDX) from the controller will connect directly to the - Reference of the Copley. The + Reference signal is then connected to the Signal Ground (GND) of the amplifier"

I think I will eventually implement an op amp to convert the 0-10v 7i76 output to -10 to +10V. I'll use a spindle enable signal / relay to avoid the startup issue (where the 7i76 starts at 0V, and thus would result in -10V (full reverse) if no precaution was taken.)

For now though, I might tackle other tasks and accept max speed of ~500rpm in reverse.
Attachments:
Last edit: 18 Oct 2017 03:52 by pippin88.

Please Log in or Create an account to join the conversation.

Moderators: PCWjmelson
Time to create page: 0.114 seconds
Powered by Kunena Forum