Acer 486 Specifications download pdf (Page 30)

22 PCA-6143P User's Manual

å RS-422 signal wiring

RS-422 is used for long-distance point-to-point connections. RS-

422 originally used four wires for one-way communication (with

devices such as display terminals or printers) but was later

adopted by industry for simultaneous two-way communication by

doubling the number of wires.

Each pin on the first device connects to a corresponding device

on the second. Flow control lines manage the communication.

The following table shows pin connections:

Computer A Computer B

Pin Signal Pin Signal

1 TX- > 4 RX-

2 TX+ > 3 RX+

3 RX+ < 2 TX+

4 RX- < 1 TX-

5 GND < > 5 GND

6 RTS- > 9 CTS-

7 RTS+ > 8 CTS+

8 CTS+ < 7 RTS+

9 CTS- < 6 RTS-

å RS-485 signal wiring

In a typical RS-485 application the host device requests data from

a slave module then listens for the response. The host transmits

and receives data on the same pair of wires. Software handles the

flow control; no other wires are needed.

Pin assignments appear in the following table. Pins 1 and 4 share

the Data+ wire. Pins 2 and 3 share the Data- wire.

Data+

Data-

1 2 ... 25 26 27 28 29 30 31 32 33 34 35 ... 38 39

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Acer 486 Specifications Page 30