Blue Heat/PCI User’s Manual, Connect Tech Inc. 39 Revision 0.11 Figure 14 below describes a 2 wire cabling scheme between a port on the Blue Heat/PCI RS-422/485, Opto, Opto RS-422/485 or Universal Blue Heat/PCI RS-422/485 adapter to a port on the RS-422/485 peripheral. Figure 14: RS-422/485 wiring diagram (2 wire)
RTS +
RTS -
CTS +
CTS -
TxD +
TxD -
RxD +
RxD -
RxD + TxD +
RxD - TxD -
RTS -
CTS -
RTS +
CTS +
SR SR
Blue Heat/PCI RS-422/485 adapter
Universal Blue Heat/PCI RS-422/485 adapter RS-422/485 peripheral
2
1
3
4
5
6
7
8
9
RTS +
RTS -
CTS +
CTS -
RxD +
RxD -
TxD +
TxD -
TxD + RxD +
TxD - RxD -
RTS -
CTS -
RTS +
CTS +
SR SR
Blue Heat/PCI Opto adapter
B
lue Heat/PCI Opto RS-422/485 adapter RS-422/485 peripheral
1
3
2
4
5
6
9
7
8

Note:

In half-duplex mode it is assumed on the Blue Heat/PCI Opto

adapter that TxD (-) is connected to RxD (-) and TxD (+) is

connected to RxD (+) via jumpers JA7, JB7, JC7, JD7 and

JA8, JB8, JC8, JD8.

Technical Tip:

The RS-422/485 electrical interface consists of a differential

signaling scheme. You should always connect the signals with

twisted pairs.