IC1474A-F 703 p. 1 / 2
5853
Port Powered RS-232 to RS-422 Converter,
DB9F to DB9F
Product Code IC1474A-F
This is a port-powered, two-channel RS-232 to RS-422 converter. It converts TD and RD RS-232
lines to balanced RS-422 signals. The unit is powered from the RS-232 handshake lines DTR and RTS.
Only one of these lines must be present, and the unit will work regardless of whether the lines are high or
low. Both the RS-422 driver and receiver are enabled at all times.
To satisfy the requirements of some software, the RS-232 handshake lines are looped back (tied
together). RTS is connected to CTS, and DTR is connected to DCD and DSR.
Connections
This converter is configured to transmit both directions between an RS-232 and RS-422 system. The
RS-232 side is pinned out to connect directly into the COM port on your computer or any other DTE
device (Table 1). The RS-422 side of the converter is pinned out as described in Table 2.
When connecting to a RS-422 system, the converter must be connected with the proper polarity as
shown in Figure 1. When no data is being sent the RS-232 line is negative and the RS-422 line TD(A) is
negative with respect to TD(B).
Table 1 - RS-232 Pin Out
Table 2 - RS-422 Pin Out
Signal
DB9 Signal Pin #
Signal
DB9 Female Pin #
TD
RD
3
2
7
8
4
6
1
5
TD A (-)
TD B (+)
RD A (-)
RD B (+)
GND
8
3
2
7
4, 6
RTS
CTS
DTR
DSR
DCD
GND
Figure 1 - Connection to an RS-422 System
Converter
RS-422
DB9 female
8
TD(A)-
TD(B)+
RD(A)-
RD(B)+
GND
RD(A)-
RD(B)+
TD(A)-
TD(B)+
GND
3
2
7
4
Black Box Corporation - 1000 Park Drive - Lawrence, PA 15055-1018
Tech Support and Ordering: 724-746-5500 - Fax: 724-746-0746
To contact us about Black Box products or services: [email protected]
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