Messages are routed between devices as broadcast (simultaneous transmission of same message) or controlled mode (i.e., specific unit addressing).
455U-D has three available models in terms of functionality:
Bell202 or V23 functionality (455U-B).
405U-D end of life compatibility mode (455U-C).
Full functionality RS232/485 modem, addressed/broadcast modes/ Optimal Path Routing for Modbus RTU, DF1 and DNP-3 (455U-D).