I also have a problem with Pictory and Modbus RTU Master. I found the tutorial "
https://revolutionpi.com/documentation/ ... tu-master/" to lack a couple of important aspects (which is to a degree true in all the RevPi tutorials):
- there was no overview of what was to be achieved. In this case using Pictory to set up a Modbus RTU Master. Where does this configuration sit? Is it a global service? How can the results of this configuration be used?
- there was no useful debugging instructions. It took some time before I found that "check the Modbus_Master_Status register for the error code" meant "open a console and use piTest -r to . ."
There is a utility mbpoll which can be installed with apt. The command (using the necessary values):
mbpoll -m rtu -a 1 -r 0x03e8 -0 -c 3 -t 3 -b 9600 -P none -v /dev/ttyRS485
does produce the expected results, short-circuiting the first two suggestions offered. The 3rd link to video tutorials points to the web tutorial..
I also ran
$ tail -50 /var/log/revpi-server.log
and found an alarming number of Python exceptions, including some nodered messages though I have disabled nodered in Cockpit.
It seems a lot more simple to focus on command-line Python.