RS486 and MODBUS RTU

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r_merc
Posts: 6
Joined: Sun Mar 08, 2020 12:31 am

RS486 and MODBUS RTU

Post by r_merc » Sun Mar 08, 2020 12:39 am

I am trying to run the Example Code and am not getting the slave Controllino Maxi Pure to respond to the master Maxi Pure. I can't figure out what I am doing wrong.

r_merc
Posts: 6
Joined: Sun Mar 08, 2020 12:31 am

Re: RS486 and MODBUS RTU

Post by r_merc » Sun Mar 08, 2020 7:14 pm

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-Ma ... or-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)."

r_merc
Posts: 6
Joined: Sun Mar 08, 2020 12:31 am

Re: RS486 and MODBUS RTU

Post by r_merc » Thu Mar 12, 2020 12:05 am

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

ControllinoModbusSlave.poll(ModbusSlaveRegisters, 8);

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
Posts: 6
Joined: Sun Mar 08, 2020 12:31 am

Re: RS486 and MODBUS RTU

Post by r_merc » Sun Mar 22, 2020 4:55 am

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?

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