[r_merc]

OK here is a new twist on this. If I remove all the digitalWrite() form the sketch I can get the Mast and slave to communicate. With the digitalWrite in the Slave the communications fails. Any Ideas?

[r_merc]

I have a similar set up and one Maxi is com 4 and the other is com 3. Sounds like what you are doing is correct.

[r_merc]

I have a similar set up and one Maxi is com 4 and the other is com 3. Sounds like what you are doing is correct.

[r_merc]

I added some troubleshooting lines to the slave code and discovered that when the line

ControllinoModbusSlave.poll(ModbusSlaveRegisters, ;

is called that the controllino resets and starts the sketch again. Sometimes it will run through the loop 2,3 or 4 times and then start over.

Anyone have any ideas why that would be happening?

[r_merc]

I was reading and I came across this. So are they talking about modifying Modbus.h?

“Modbus Master-Slave library for Arduino (ModbusRtu.h) was taken from the website: https://github.com/smarmengol/Modbus-Master-Slave-for-Arduino

It was necessary to modify setting of the PORTJ for pins DE and RE control. These pins are located at the PORTJ and on the pins PIN6(DE) and PIN5(RE).”