3. External Connection
22
COM-1PD(USB)H
Example Connections
The RS-422A/485 interface provides a differential method of transmission, in which relative potential
differences between two conductors (positive and negative) are meaningful as signals.
For the converter, a twisted-pair cable (balanced line) should be used as possible to improve noise
immunity.
RTS
-
RxD
-
TxD
-
TxD+
RxD+
RTS+
CTS+
CTS
-
SG
RTS
-
RxD
-
TxD
-
TxD+
RxD+
RTS+
CTS+
CTS
-
SG
External device
Figure 3.2. Example of connection with RTS and CTS connected to external device in full-duplex
mode
External device
RxD
-
TxD
-
TxD+
RxD+
SG
RxD
-
TxD
-
TxD+
RxD+
SG
Figure 3.3. Example of connection with RTS and CTS self-looping in full-duplex mode
External device
TxD
-
TxD+
SG
TxD
-
TxD+
SG
Figure 3.4. Example of connection in half-duplex mode
CAUTION
Connecting the converter by incorrect wiring can cause a fault in the converter and/or the device
connected.
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