User's Guide

Technical Description
OMG-CONV-485-ISO Page 10
Technical Description
The OMG-CONV-485-ISO converts an existing RS-232 serial port into a field
selectable RS-422/485 port for industrial automation and control applications.
Connector Pin Assignments
RS-232 Signals (DB-25 Female)
Signal Name Pin # Mode
GND Ground 7
RD Receive Data 3 Input
CTS Clear To Send 5 Input
DSR Data Set Ready 6 Input
DCD Data Carrier. Detect 8 Input
RI Ring Indicator 22 Input
TD Transmit Data 2 Output
RTS Request to Send 4 Output
DTR Data Terminal Ready 20 Output
Note: These assignments meet EIA/TIA/ANSI-232E DTE
Technical Note: The modem control signals are biased in the following
fashion: RTS and CTS are connected, DTR is connected to DCD and
DSR, and RI is tied inactive.
RS-422/485 Pin Assignments (6 Position Screw Terminal)
Signal Name Pin # Mode
RDB RX+ Receive Data Positive 1 Input
RDA RX- Receive Data Negative 2 Input
TDB TX+ Transmit Data Positive 3 Output
TDA TX- Transmit Data Negative 4 Output
GND GND Ground 5
SHIELD SH Shield 6