7i76e digital input VFD digital out spindle to speed wiring

Hello everyone, I am trying to finish setting up my new VFD with mesa 7i76e and having some issues with understanding how to wire VFD's digital output to 7i76e's inputs. I have a basic spindle control with 10v setup done and working but I also would like to linuxcnc to wait for spindle at speed command, for that I have setup digital output at VFD and can successfully measure 24v between VFD's DO1 and COM when spindle is idle and 0v when spindle is at speed, but I am pulling my hair out how to make 7i76e read that.... my first thought was that connecting DO1 from VFD to one of the TB6 inputs will work, but it does not, and I guess it makes sense because COM port on VFD and field power ground on mesa (TB1 pin 8) are not shared, however COM from VFD is already connected to TB4 for spindle control. This is probably something very obvious but I obviously lack some knowledge in this field. Attached VFD wiring diagram

 

Are all COM pins connected?

I don't see why you would have 24V on D01 since it
says its an open collector output...

Yeah, there are only two COM ports (DI and DO) and as far as I can tell they are connected. There is a jumper between +24v and PLC ports (without that jumper digital inputs does not work) and I have +24v connected to Relay 1 that then goes to solenoid valve for ATC (Relay 1 is closed when spindle is idle). After I have posted this question I had the same exact thought, why the hell there is 24v on D01 so I've tried disconnecting everything (including jumper to PLC) and there is still 24v there... I guess the way it is supposed to be is that I wire 24v from mesa field power to D01 and then COM goes back to one of the mesa inputs, right?

I would probably first check that the COM pin near the DO1 pin is not connected to any other COM pin on the VFD

Field 24V to DO1 and DO1s COM to 7I76E input would be correct
_IF_ the COM pin next to D01 connects to nowhere else but the emitter
of the OPTO as shown.

To avoid damage, I would put a 1K resistor in series with field 24V before connecting it to D01.

There is only 2 COM ports on vfd (diagram shows 3), and I can ring both of them with multimeter (connected). I have tried disconnecting everything from vfd and there is definitely 24v between DO2 and either of two COMs, DO1 was the same yesterday but today there is no voltage between it and COM, I suspect I might have fried it… this 100% has nothing to do with parameters as this vfd has multiline screen and very easy to read/setup

So if the COM pins are really common grounds
(and DO1 still works) the wiring should be:

Field 24V --> 1K_resistor_pin1 --> 1K_resistor_pin 2--> DO1 --> 7I76E INPUT
VFD COM --> Field GND

Ok, sorry, I played a bit more and this is what I’ve found. DO1 -> COM no voltage (not sure why I have seen yesterday, maybe something else was connected incorrectly), if DO1 is set to False in parameters then multimeter between DO1 and COM does not ring (open), if DO1 set to True then it is closed to COM (any COM). Sorry if my terminology sucks, I am really bad at electronics Not sure about voltage on DO2 though…, anyway, thanks for your help

OK, that sounds correct, so my wiring in the previous post should be right.

Only I feel so stupid that I am not really sure that I am reading this correctly… Do you mean that I take wire from field 24v, connect it to pin1 of resistor, then two wires from pin2 of resistor one goes to vfd do1 and another to mesa input?

Yes
(plus VFD COM to Field power Common)