For a project in the concept stages, I am looking at a variable number (3-12) of small Arduino units (UNO, or hopefully Nano) spread over a mid-sized area (in electronic terms, small for humans) of 5m x 10m.
I am looking at Modbus over RS-485 to connect the processor modules. Since I have to run power wires, adding a few more for comms isn't a big deal. I looking at the half-duplex MAX485 based boards. Which appears to put me solidly in the master-multislave configuration. That is fine, I can work with it.
What is the preferred library for Modbus? (ie., which library is best supported)
There are two libraries in the Arduino IDE, ModbusMaster and ModbusRTU_Slave. Are they usable, are they any good, should they be avoided? I noticed they are by two different people, but will they work together?
I haven't the space for the larger boards to add additional serial ports and I want to leave the current serial port available for debug output and data transfer with the PC. Will the libraries listed above (either from the suggested list or the two from the IDE library) work with software serial?
I tried the google thing on the latter, but only came up with results from 2010. I'm not sure they apply today, so I am looking for fresh updates.
Any other advice, hints, tips, or suggestions are welcome as well.