Advantech PCL-746+, Руководство пользователя

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3 0 PCL-746+ User's Manual
RS-422 signal wiring
For RS-422 interface, the wiring is based on one-to-one principle and
the connections are as follows:
DB-25 Male: PCL-746+ DB-25 Male or Female:
Terminal
Pin Signal Pin Signal
2 RxD+ 3 TxD+
3 TxD+ 2 RxD+
4 RTS+ 5 CTS+
5 CTS+ 4 RTS+
6 RTS- 22 CTS-
7 GND 7 GND
20 RxD- 8 TxD-
8 TxD- 20 RxD-
22 CTS- 6 RTS-
Terminator Resistors setup
The signals DSR, DTR, DCD are shorted internally on PCL-746+ card
whist operating in the RS-422 mode.
The terminal resistors for impedance matching on the PCL-746+ are not
installed at the factory. The user can install the resistors with the
appropriate resistances according to the cards application. Each
terminal resistor corresponds to a different channel for TxD+/- or
RxD+/- lines. Usually, these resistors are needed for both ends of the
communication wires and the value of the resistors should match the
characteristic impedances of the wires used (approx 120 ohm).