Awesome, thank you Ralph! Working example of INI file is exactly what I needed because I have managed to get communications working, see here: https://forum.linuxcnc.org/10-advanced-configuration/59295-help-with-modbus-needed#350109
And getting correct values for "First element" was now my issue. I will test it later today. Viesturs pirmd., 2026. g. 5. okt., plkst. 04:31 — lietotājs Ralph Stirling via Emc-users (<[email protected]>) rakstīja: > > I have an Invertek Optidrive E3 as well, with usb-to-rs485 control. I've > uploaded my files to: > > https://gab.wallawalla.edu/~ralph.stirling/projects/linuxcnc/rmc2/ > > -- Ralph > > -- Ralph > ________________________________ > From: Viesturs Lācis <[email protected]> > Sent: Friday, 02 October 2026 08:31:24 > To: Enhanced Machine Controller (EMC) <[email protected]> > Subject: [Emc-users] How to modbus? > > CAUTION: This email originated from outside the Walla Walla University email > system. > > > Hello! > > I have a VFD that I can nicely start and stop with an output from 7i84 > board, but customer does not like the fact that I replicated original > solution of setting spindle speed with potentiometer. They want to do > that from g-code so that it is consistent and not a subject for > operator to mess up. Unfortunately all analog outputs on 7i33 board > are already used for servodrives so I would prefer avoiding adding > more boards. > It is Invertek Optidrive E3 VFD and I have usb-to-rs485 converter. > lsusb shows it as CH340 chip. With some other commands I was able to > determine that it is using ttyUSB0 port. > > Here is the section of Optidrive E3 manual that describes the modbus > message contents: > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fibb.co%2FPzFsq8fP&data=05%7C02%7Cralph.stirling%40wallawalla.edu%7Ca7a66095adff468c2bba08df209a577a%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C639265519863636344%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=Y7F4XbOa748AUY0XuQIUuRTfb56KPO5GbP4GGq72LPc%3D&reserved=0<https://ibb.co/PzFsq8fP> > > And according to manual I can still have start/stop signal the way I > have now even when the drive is in Modbus mode so what I would need is > to send the frequency value (optionally - read actual frequency to > determine "spindle-at-speed" and "spindle-is-stopped"): > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fibb.co%2FPGXK2gW5&data=05%7C02%7Cralph.stirling%40wallawalla.edu%7Ca7a66095adff468c2bba08df209a577a%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C639265519863664042%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=Gdh%2BtBv63tW%2FZd%2FI0Vv9FtqfN4J0msaIHSOy1GoeOqw%3D&reserved=0<https://ibb.co/PGXK2gW5> > > I tried searching web of how to start and went for mb2hal route. > In HAL file I have: > loadusr -W mb2hal config=mb2hal.ini > > Here is contents of mb2hal.ini file: > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpastebin.com%2Fh9qHcPR1&data=05%7C02%7Cralph.stirling%40wallawalla.edu%7Ca7a66095adff468c2bba08df209a577a%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C639265519863688206%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=SGGyEWT%2BhqYxWeJOw60njHxsGKt8m5y%2Bzpp%2BJe4%2BH%2Bs%3D&reserved=0<https://pastebin.com/h9qHcPR1> > > I tried looking at pins of mb2hal component in HalShow but the only > thing that was changing was a pin that shows number of errors. > mb2hal.ini file has 2 entries about debug messages but I did not even > understand where to find them so at the moment I have exactly no idea > what is wrong and how to proceed so I would appreciate if someone > could hold my hand and then gently poke in correct direction. It seems > like a basic thing of what people are doing with VFDs over modbus but > I have never done that. > > Viesturs > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Femc-users&data=05%7C02%7Cralph.stirling%40wallawalla.edu%7Ca7a66095adff468c2bba08df209a577a%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C639265519863713143%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=tiWQGSo0sbn8GttZrnbZJPA4hj6onpeNWHwJj%2F4wX4E%3D&reserved=0<https://lists.sourceforge.net/lists/listinfo/emc-users> > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
