No such file or directory: '/dev/ttyRS485'

Hi,
I bought another RevPi Connect+ device but I have again the same modbus communication problem with Modbus RS485 on /dev/ttyRS485

- if i use '/dev/ttyUSB0' (with usb/rs485 adapter) all work correctly !!!
- if i use '/dev/ttyRS485' (with two wire +- connected to modbus rs485 pinout) doesn't work !!!

Why the /dev/ttyRS485 is very problematic? How can you check surely the problem and how to solve it?

Thanks

Please provide logout put from dmesg and error messages if applies.

Nicolai

Hi,

I'm having the same problem with a Connect. I cannot get modbus to work in Codesys with RS485 connector on the front. (see image in this post: https://revolutionpi.de/forum/viewtopic ... sys#p13118)

I followed the comments from Nicolai and turned off PiModbus Master and Slave in Pictory.

I also followed the Codesys steps here: https://revolutionpi.com/tutorials/beis ... u-slave-2/ - This suggests to use tty/USB in the CODESYSControl.cfg settings.

I checked these steps per an old post from Amar: https://www.fleaplc.it/index.php/tutori ... ys-control

Somebody is suggesting to use /ttyRS48 (no '5') and set to port 6: https://forge.codesys.com/forge/talk/Ru ... 2239cdd18/ - but that's not working either.

I'm a bit lost with all these different options? What is the official suggestion from Kunbus? And how should i troubleshoot this: do i check dmsg first? Can I check any log in Codesys that may be helpful?

Regards
Koen