Moxa Technologies CP-114 Series user manual RS-485 Programming

Serial Programming Tools

RS-485 Programming

If you intend to do RS-485 communication with Industio CP-114 Series, please follow the RS-485 programming guide below and also refer to the chapter, “Connection Cable and Cable Wiring”, for more RS-485 operation details.

The Industio CP-114 Series supports only 2-wire half-duplex RS-485 communication. Data+/- pins are served for both data transmitting and receiving, depending on the mode selected: either Automatic Data Direction Control (ADDC) or By RTS mode.

Automatic Data Direction Control Mode

Automatic Data Direction Control scheme is the best solutions for RS-485 applications. The data mode selection jumper for the port should be set to Left position, to be able to use Automatic Data Direction Control Mode.

Under this mode, no extra code is required to control the data transferring (data transmitting and receiving), which is automatically managed with the intelligent hardware mechanism. That is, RS-485 programming in this mode is just as simple as RS-232/RS-422 programming.

By RTS Mode

If the data mode selection jumper for the port is set to Right position, By RTS mode is used. The port is ready for transmitting data if RTS signal is asserted and ready for receiving data if RTS signal is not asserted.

RTS scheme is a traditional way and suitable for most system, including Windows NT , Windows 95/98 and DOS, that permits RTS control from application programs. This mode should be compatible with most of the already-made RS-485 applications.

How to transmit and receive data for Windows NT, 95/98 & DOS

We recommend you to configure Industio CP-114 Series ports as follows in order to acquire precise timing control in RS-485 2-wire transmission.

Industio CP-114 User's Manual 4-7