Moxa Technologies CP-132U - Manual (Page 72)

CP-132U Series User’s Manual 4-4
RS-485 Programming
If you intend to use your CP-132UL Series board for RS-485 applications, you can refer to
the RS-485 programming guide below, and also see the chapter, “Connection Cables and
Cable Wiring,” for more details about RS-485 operation.
The CP-132UL Series supports only 2-wire half-duplex RS-485 communication. In this
case, the data+/- pins are used for both data transmitting and receiving, depending on the
mode selected. Moxa’s own ADDC™ (Automatic Data Direction Control) technology is
used to switch between transmitting and receiving.
ADDC™ (Automatic Data Direction Control)
ADDC™ is the best method for switching between transmission and receiving when using
2-wire RS-485.
When using ADDC™, additional code is not required to switch between data transmitting
and receiving, since the switching mechanism is managed automatically by the board’s
built-in intelligent hardware mechanism. This means that RS-485 programming using
ADDC™ mode is just as simple and straightforward as RS-232 or RS-422 programming.