7i76e VFD configuration

Hi everyone,

I recently got an OMIO X6-2200L. It comes with a USB control board for Mach3, and I decided to switch that out for a Mesa 7i76e to run LinuxCNC!

After a couple days of wiring and testing and messing about (the workshop is ~30min away from home, so no nighttime fiddling around for me), I finally made progress. X, Y, and Z all now move as expected, and their home switches also work. Got the 7i76e on ethernet, with a USB WiFi adapter for internet connection. Everything works great. But, I can't for the life of me get the spindle to run!

I wired up the VFD to TB4 on the card by mimicking what was done on the old USB board. Here's what I did:

Mesa --> VFD

Spindle- --> GND

Spindle out --> AI1 (Analog Input)

Spindle+ --> 10V

Spindle Dir+ --> X1 (Programmable Input, factory-default is "FWD")

From OMIO, the VFD came with the COM terminal hard-wired to GND.

But, I get no spindle control when trying to test in PNCCONF, or in LinuxCNC itself.

If any of you have any ideas what exactly I'm doing wrong, please let me know! I'll include links to the manual for the VFD, Mesa card, and the Mesa wiring diagram I used!

Thanks in advance

Mesa Manual (Google Drive): drive.google.com/file/d/1k8DLbwOV4iAClF1...k0Z/view?usp=sharing

Mesa Wiring (Google Drive): drive.google.com/file/d/1q1zLapXIJt5COUq...-b4/view?usp=sharing

VFD Manual (Google Drive): drive.google.com/file/d/1Nc3Zb2N7aPDKeYj...iO5/view?usp=sharing

Could you post copies of your hal and ini files, so we can check them for mistakes.

Yeah, I can do that tomorrow!

Bring out the multimeter and measure the voltage between Spindle- and Spindle out. If you see a reasonable voltage between 0-10V then the problem is in the vfd config. If you don't see any voltage the problem is in linuxcnc. Make sure you set spindle-enable to true even if you don't use the signal, it must be true to output a voltage.

Got it. Will do.

How do I set spindle enable to True? In the PNCCONF spindle test menu I didn’t see an enable button. In LinuxCNC I think it is F9?

Something else to note is that in the TB4 tab in PNCCONF I don’t actually get the ability to set what each pin does, only the option to select “Spindle”. Is this normal?

So I’m getting between 0 and 10V across those terminals. On the VFD, the display is blinking “0.0”, and as I increase the spindle speed in LinuxCNC, changes up to 400.

My spindle is supposed to be 6k-24k RPM. So there is some communication to the VFD, but it may not be right, and I can’t get the motor to come online...

it depends upon the spindle motor and what your settings are in the VFD.

some spindle motors are designed to operate at 400hz,

check the settings within the VFD with regards to the set number of poles and its current rating and settings and also the motor frequency (from the drive to the motor).

120 * 400hz / 2 pole = 24000 rpm

Minimum frequency (setting in the drive) = 6000rpm * 2pole / 120 = 100hz

Alright, I got it worked out. My VFD has an especially bad manual, but multimeters are the best.

I ended up doing the following:
Mesa 7i76e --> VFD

Spindle- --> GND
Spindle Out --> AI1 (Configured to be 0-10V input)
Spindle+ --> 10V

Ena+ --> X1 (Configured to be "FWD" in VFD settings)
Ena- --> COM (Grounded end of VFD 24VDC supply)

I belive the way this VFD works / is currently configured is that it looks for X1 (normally at +24V) to be brought to ground. When this happens, like when the mesa closes the "enable" switch, the spindle is turned on, set to the RPM configured by the mesa's "digital potentiometer". I could spend more time poking around trying to figure out the best way to actually have direction +/- control, but I really don't need it and I'd rather spend time getting a spoil board and fixture plate machined up and mounted!