tsimpson - 2018-02-26

Greetings,

All afternoon and evening I have been fighting this. I have a fully licensed Pi with 3.5.12 and a Wago PFC200 with just the trial license. The configuration I am trying to acheive is the wago as "master" and the Pi as slave. Everything shows like it is a good connection. The only thing I see out of the ordinary is the double blue line under the Pi slave device. The slave device is "green lighted" on both the Ethernet adaptor, and the ModbusTCP slave branched out of it. I also have the expected values at each mapped holding register.

On the Master side, the Wago, I have green lights for Ethernet device, ModbusTCP master and modbusTCP slave. Under ModbusTcpSlaveParameters, unit ID matches the slave (2), IP Address matches the slave, and port matches the slave (502). I am set to function code 3, Offset 0x0000 (matching the Data model Start addresses of 0 for Holding register on the Pi). The Pi's variables begin at %IW0 which has a line through it. On the slave there is a total of 10 registers configured in the Channel, 7 of which I am using (again, all 7 has correct data). Lastly, back on the master, I have a read length of 7.

Both sides are set to "Enabled 2" and all variables are being read/written in the MAIN POU. All of this and yet nothing comes through to the master (the Wago). All values are 0 despite having values in the corresponding registers on the slave (Pi). The only test I have not done is to take the router out of the equation and connect the master and slave on their own network. I do however have the gateway set to the internal side of the router.

Any ideas or suggestions??