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

[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?

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.

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.

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?

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-

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.

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.