We have PLC 5/40 redundant sytem with 1785-BCM and 1785-KE. SCADA is connected to the PLC system through RS-232 port (through modem) to 1785-KE. I want to take the DH+ information into Quantum PLC(on Modbus TCP/IP). I also have a suitable converter that converts DH+ to Modbus TCP/IP. However when i try to read the data from the PLC the communication between SCADA and PLC fails. I have connected my DH+ converter to channel 1A (of PLC 5/40) while the SCADA is communicating through channel 2A (of PLC 5/40).Only read request is given from Quantum PLC. Can anybody pls tell me as to why such problem is occuring.