Orion electronics supplies dataforth ldm 422, which is a compact rs-232 to rs-422 converter. It features a complete electrical isolation barrier and heavy-duty electrical surge protectors. It is enclosed in an aluminium enclosure small enough to mount on the back of a typical computer equipment, saving desk space. Isolation is provided through optical isolation and dc-dc converter. Communication is designed for full duplex operation over two wire pairs. Outputs are tri-state allowing multi-dropping of up to 32 units. Hardware handshake is available over two separate wires pairs. Data rates are 75 to 19,200 bauds. Rs-232 interface supports rts, cts, dsr, dtr and rlsd. The ldm 422 can be used to convert two sets of send receive signals using rts and cts circuits as second data channels. Ldm 422 can communicate over a length of 12 km to 1.8 km respectively. Self-powered 12 v ac and host powered [draws ±12 v power from pin 9 and 10] models are available. A convenient null modem switch is provided for data lines. For installation and trouble shooting each unit have diagnostic leds on transmit and receive line. Rs-232 connections are through 25-pin male or female eia connector and field connection is made through screw terminations.
