Instruction manual

28 SBC-400 User's Manual
by the 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 Ground < 5 Ground
6 RTS- > 9 CTS-
7 RTS+ > 8 CTS+
8 CTS+ < 7 RTS+
9 CTS- < 6 RTS-
RS-485 signal wiring
In a typical RS-485 application, the host device requests data from
a slove 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 Date+ wire. Pins 2 and 3 share the Data- wire.
Computer A Device B