Features

Model 485COSR, RS-232 to RS-485 converter, converts unbalanced, full-duplex RS-232 signals to balanced full-duplex (4-wire) or half-duplex (2-wire) RS-485 signals. The RS-232 port has a female DB25S connector with pins 2 (TD input) and 3 (RD output) supported. Protective Ground (pin 1) and Signal Ground (pin 7) are also passed through. Pins 4 (RTS) and 5 (CTS) are tied together. Pins 6 (DSR), 8 (CD), and 20 (DTR) are tied together, but not passed through the converter. The RS-485 port has a male DB25P connector with Send Data outputs on pins 2 and 14, and Receive Data inputs on pins 3 and 16, or 5 and 17. No special software requirements are needed since the RS-485 driver is enabled by the first transition on the RS-232 side of the Transmit Data line (Pin 2). Any transmission on the TD line keeps the RS-485 driver enabled by preventing the mono-stable multi-vibrator from timing out. The transmitter is disabled approximately 1 ms after the last transmitted character. This 1 ms timeout allows continuous transmission of data at 9600 baud or higher. A 12 VDC external power supply is required (not included, sold separately).

Downloads

Datasheet 1