I am using Siemens S7 416 plc for turbine control G60 for generator protection, AVR for excitation, BN for machine monitoring. I have to make modbus communication with PLC, AVR, BN, G60. my question is that CP441 is for point to point communication or i can do multidrop connection taking only one CP 441 card or i have to take two card one Cp 441-1 and one CP 441-2 for communication. Please reply soon.

 

as long as all your partners are MODBUS slaves and have RS485 interface, you can load Siemens MODBUS master library on a single CP441 equipped with RS485 port, which allows multi-drop communication. Be aware that CP441 Modbus driver and port interface are sold by Siemens as separate components.