Modbus VFD startup delay?

Just for fun I thought I'd try to use modbus - specifically gs2_vfd - to control my mill spindle.  VFD is a GS3 from Automation Direct, currently using 0-10v.

After some config problems (tty permissions), the USB-RS-485 adapter and LCNC are sort-of talking to the VFD.

I'm getting 'failed to set register - communication timed out' errors, but I think I have a more serious problem...

The way I've set up my electrical system, when estop is asserted, all the drives and VFD have no mains power.  24vdc is present for all sensors, Mesa, and so forth, but no drive bus power.

Until I de-assert estop, the VFD is dead and can't communicate with LCNC - so LCNC shuts down due to a 'no response' error.  I got around that for testing by taking it out of estop and energizing the contactors (having bypassed some HAL safety logic) and then starting LCNC.

Which got me thinking... is there a way to delay LCNC trying to communicate with the VFD until after I de-assert estop?

I'm not willing to change my estop scheme to permit power to the VFD when estop is asserted.  And the VFD has no separate logic power input like some servo drives.

Putting the 'loadusr Wn...' in the postgui file didn't do the trick.  I don't take it out of estop until the GUI is up and stable.

There's no point in trying to troubleshoot the read/write unless I can force LCNC to wait until after I de-assert estop.  Anyone have a thought on this?
 

There are probably ways to start the modbus component and the associated hal file through a custom Mcode but I don't see how you would be able to restart the modbus connection after an estop event.
It seems that this should really be handled in the modbus component itself.

Thanks.  I'm not going down the component editing rabbit-hole, so I'll stick with the existing analog control.

I don't quite understand your problem. I control my VFD via MODBUS and when communication is lost an error message appears, but once communication is re-established everything returns to normal. The error you describe would only appear if at the start of LNC there was no communication with the VFD. If I disconnect the power supply to the VFD only the error message appears, but once I re-establish it everything returns to normal.

Let me clarify, I am using the VFDMOD component with a USB to 485 converter and MESA MODBUS through the RS422 port of the MESA cards, and that error that you describe, that is, LCNC shuts down at startup only if there is no communication with the VFD when it is starting up. Once LCNC starts and if there are subsequently communication problems with the VFD, it only tells me that there is an error but does not shut down.

@COFHAL-

Yes, because my VFD is not powered at startup, LCNC shuts down with a modbus error.

What I was asking earlier is if there is a way to delay LCNC trying to communicate with the VFD until after LCNC has finished starting up.  Specifically, after estop is deasserted and machine-on is true.

Ideally, estop-clear would trigger LCNC to attempt communication with the VFD, and perhaps prohibit machine-on if communications weren't established after some time.

So, once the startup procedure has successfully completed, does your component reconnect automatically after a powerloss in the VFD? If so then my comment above would not be accurate and the startup delay was really all that is needed.

what about the gs2_vfd enable pin?

The 'gs2_vfd' component does not seem to have an 'enable' pin:
linuxcnc.org/docs/stable/html/man/man1/gs2_vfd.1.html

It does actually have an enable pin but it isn't listed in the documentation: