Moxa's CP-134U and CP-134U-I Series serial port multiplexer cards are designed for long-distance, multipoint PC-based industrial automation systems. Automatic Data Direction Control for precise on-board RS-485 communication requires precise time control for turning the line driver on and off. Moxa Turbo Serial Engine powering the CP-134U card? The chip is supplied with ADDC® and allows RS-485 to be used as easily as RS-232. The 4 RS-422/485 serial ports on the cards also have a data rate of 921.6 Kbps. In RS-485 mode, 31 daisy-chained RS-485 devices within 1.2 km can be added to the serial port. For long distance RS 485 communication, the 2 kV optically isolated model can be preferred. Windows COM and Linux/Unix TTY drivers are provided for all Moxa cards and other embedded operating systems such as WEPOS.