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).
Figure 1 - Connection to an RS-422 System
8
3
2
7
4
TD(A)-
TD(B)+
RD(A)-
RD(B)+
GND GND
RD(A)-
TD(A)-
RD(B)+
TD(B)+
422PP9R
DB9 female RS-422
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: info@blackbox.com
Table 1 - RS-232 Pin Out
Signal DB9 Signal Pin #
TD 3
RD 2
RTS 7
CTS 8
DTR 4
DSR 6
DCD 1
GND 5
Table 2 - RS-422 Pin Out
Signal DB9 Female Pin #
TD A (-) 8
TD B (+) 3
RD A (-) 2
RD B (+) 7
GND 4, 6
Converter
IC1474A-F 703 p. 2 / 2 5853
Biasing Resistors
The biasing resistors for the RS-422/RS-485 receiver are 4.7k Ohm resistors. These resistors are
labeled R1 and R2 (See Figure 2).
Figure 2
+5V
DCD
1
3
2
5
TD
GND
RD
R2
7
8
4
6
CTS
DTR
DSR
RTS
Circuit
Power
Conversion
R1
4.7k
TD(B)+
TD(A)-
RD(B)+
RD(A)-
GND
3
8
7
2
4
4.7k
RS-232
DB9 female
RS-422
DB9 female
Specifications
Communication: RS-422
Data Rate: 115.2 kbps max.
Power: Port-Powered from handshake lines on the RS-232 side.
Dimensions: 6.1 x 3.3 x 1.7 cm (2.4 x 1.3 x 0.66 in)
Temperature Rating: 0 to 70°C
NOTE: When using an external supply, the supply should be connected only to specifically
labeled power inputs (power jack, terminal block, etc.). Connecting an external power supply to
the handshake lines may damage the unit. Contact technical support for more information on
connecting an external power supply to the handshake lines.
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: info@blackbox.com
Model Number: IC1474A-F
Description: 9-Pin Port-Powered RS-422 Converter
Type: Light industrial ITE equipment
Standards: EN 50082-1 (IEC 801-2, IEC 801-3, IEC 801-4)
EN 50081-1 (EN 55022, IEC 1000-4-2)
EN 61000 (-4-2, -4-3, -4-4, -4-5, -4-6, -4-8, -4-11)
ENV 50204
EN 55024
