varlogic modbus communication user manual - Schneider Electric

NRC12Modbus applicationUSER’S MANUALconnection is used only in a 4-wire connection. RS-485 -connection is either a2- or a 4-wire connection.Modules are connected sequentially, branches on the cable are not allowed.The bus is terminated with terminator resistors. One terminator to each end ofthe bus. One module feeds biasing voltages to the bus. Each module isgrounded via a PG (Protective Ground) terminal.MCUMCU MCU MCUMCU MCU MCUMCUMCUPicture 3: Correct structure of an RS-485 bus5.3 2-wire connection in an RS 485 busMCU 1 /PCMCU 2(PFC-slave)Picture 4: 2-wire connection in an RS-485 busPicture 6 describes connections in an RS-485 bus. Suitable cable types aree.g. Belden 3107A, 7201A, 9842 and Alpha Wire 6072C.6