I am trying to get a few data points from three different Eurotherm controllers (PV and setpoints) into a GE rx3i system with a CPU315 plc along with an ETM001 module. I know the controllers and the ETM module can talk over Modbus TCP. First question is what is best way to set up comms, is it better to have the rx3i system be the master and request data from the three controllers round robin or is it better to have the controllers be masters and have the rx3i system be the slave? I read making the rx3i be the master requires more programming (like COMM_REQ instructions). Can the setup even be done having the plc be the slave to all three controllers at the same time? One other question is outside of the manual does anyone know where to locate example code on how to read in data on the plc side?