This is a universal converter which  supports RS485 as well as RS422, 2  wire or 4 wire, Auto or DSR (+ or -)  control. This converter supports Tx,  Rx, DSR line. Switch setting is  provided for 2 wire/4 wire  (differential) RS485 operation (i.e. half  duplex or full duplex mode) Also  switch setting for Auto, DSR +, DSR -  control provided (for output enable on  RS485 side) It supports 32 units in  multidrop environment. This unit to  built in opto isolator and surge  protection for individual signal.  (Normal unit works on 230V AC-option  available for 10 to 40V DC voltage.)