PCI Express Boards Serial Programming Tools
RS-485 Programming
If you are using your CP-118EL Series board for RS-485 applications, in addition to reading this section, you
should also refer to Chapter 7, “Pin Assignments,” for more details about using RS-485. The CP-118EL
Series supports 2-wire half-duplex RS-485 and 4-wire full-duplex RS-485 communication. Ports configured
for 2-wire RS-485 use the Data+ and Data- pins for both transmitting and receiving data. Moxa’s own
ADDC™ (Automatic Data Direction Control) technology is used to switch between transmission and
reception.
ADDC™
ADDC™ is the best method for switching between transmission and reception when using 2-wire RS-485.
When using ADDC™, an additional code is not required to switch between data transmission and reception,
since the board’s built-in intelligent hardware mechanism automatically manages the switching mechanism.
RS-485 programming using ADDC™ mode is just as simple and straightforward as RS-232 or RS-422
programming.