7i76 not outputting 0-10v when spindle set to reverse

Hi All,

I just upgraded my VFD from a siemens (V/Hz only) to a Delixi EM60 (SVC) which requires +0-10v with forward and reverse pins unlike the siemens which wanted +-10v and enable pin.

I have modified my hal file so the spindle enable output drives the spindle reverse pin for the vfd as it does not require an enable signal and changed the spindle OUTPUT-MIN-LIMIT to 0 in the INI file from -6000 previously.

When I reverse the spindle either through M code or the axis UI, it will not rotate ccw. Spindle forward works no problem. Looking in my hal file, my understanding is spindle-vel-cmd-rpm-abs is input to the PID which outputs to spindle-output which then drives hm2_5i25.0.7i76.0.0.spinout. Therefore, because it is the absolute of the rpm command, the 7i76 should always output a positive 0-10v signal, however,  that exact HAL configuration worked fine for the siemens VFD which wanted +-10v. I have even tried linking the spindle-vel-cmd-rpm-abs straight to spindle-out, skipping the PID but that did not work either.

I have verified the spindle CW and spindle CCW pins are working correctly and the VFD sees them, however checking the spindle output voltage with a multimeter shows 0v is being output when in reverse, yet works fine from 0-10v when in the forward direction.

Is there something trivial I am missing in my HAL file? overlooking something? or possibly something else going on? My HAL and INI file are attached.

Thank guys.

EDITED: I am running Linuxcnc 2.8 with Axis gui

The 7I76 spindle interface only directly supports DIR/ENA mode
when hm2_5i25.0.7i76.0.0.spinena is false, the analog output
is forced to 0 so these connection are needed.

net spindle-ccw => hm2_5i25.0.7i76.0.0.spindir
net spindle-enable => hm2_5i25.0.7i76.0.0.spinena

Can your VFD be programmed for DIR/ENA mode?
If not you may need to ether use some of the 7I76
field I/O for the CW/CCW pins or use a SPDT relay
to steer the ENA signal to the CW or CCW VFD inputs
base on the state of the DIR output.

PCW, that makes sense and explains the behaviour I am seeing, thank you very much!

Sadly the VFD cannot be setup for enable and direction. I will reread the manual as I can setup binary logic using the 4 digital inputs which I could configure so enable is forward and if both enable and reverse are high, it is reverse. If not a simple relay like you suggested using field gpio to drive it will suffice.

Thanks again.

when hm2_5i25.0.7i76.0.0.spinena is false, the analog output is forced to 0 so these connection are needed.

I just got bit by this. Is there any way to change it (e.g. twiddling in the firmware if need be) or is this in hardware?

I'm using an Omron MX2 VFD and it only supports two ways of setting direction + enable:

• Set forward XOR reverse. Setting neither stops the motor. Setting both stops the motor.
• A "three-wire interface" that is only intended to work with "momentary pulse control" and recommends the previous interface if it's not available.

My electronics-foo is weak and I'm not sure it's possible for me to use the field I/O to solve this. I'm using the field I/O to handle my servos and sensors and all of that stuff has ground and 24V from the same DC power supply that's otherwise powering the 7i76E.

The VFD seems to have its own internal 24V power supply.

Is it safe to just link 0V from my power supply to 0V on the VFD? I'm familiar with it when it comes to smaller stuff like an Arduino but for the bigger stuff and line filters I'm a bit out of my depth. I'm used to following the diagrams in the manual...

Good call! I don't know how normal this is but there was exactly 0 voltage difference between the two and when I put the meter in current measurement mode, there wasn't even a microamp of current.