PCCOM PCI BUS 4 PORT SERIAL ADAPTER

CHAPTER 7
RS422/RS485 CABKUBG UBFIRNATUIB

7.1 RS422 Cabling Information for DB25

The communication interface follows the EIA RS422 standard. The signal assignments for a standard DB25 connector are shown below:

Pin	Description
1	Chassis Ground
7	Signal Ground(SG)
12	Transmit Data+(TxD+)
13	Receive Data+(RxD+)
24	Transmit Data-(TxD-)
25	Receive Data-(RxD-)

To connect the RS422 to other DATA TERMINAL EQUIPMENT (DTE) devices, the developers recommend using a DTE to DTE connection as shown below.

HOST	REMOTE
Ground	Ground
Signal Ground	Signal Ground
Transmit Data(+)	Receive Data(+)
Receive Data(+)	Transmit Data(+)
Transmit Data(-)	Receive Data(-)
Receive Data(-)	Transmit Data(-)

7.2 RS422 Cabling Information for DB9

The communication interface follows the EIA RS422 standard. The signal assignments for a standard DB9 connector are shown below:

Pin	Description
1	Transmit Data+(TxD+)
4	Receive Data+(RxD+)
5	Signal Ground(SG)
6	Transmit Data-(TxD-)
9	Receive Data-(RxD-)

7.3 RS485 Cabling Information for DB25

The RS485 signal assignment is shown as follows:

Pin	Description
1	Chassis Ground
7	Signal Ground
12	Transmit Data+/ Receive Data+(TRD+)
24	Transmit Data-/Receive Data-(TRD-)

The RS485 communication is based on cable sharing method, which is connected as following:

Computer at site 1	Computer at site 2
TRD+	TRD+
TRD–	TRD–
Ground	Ground

7.4 RS485 Cabling Information for DB9

The RS485 signal assignment is shown as follows.

Pin	Description
1	Transmit Data+/ Receive Data+(TRD+)
5	Signal Ground
6	Transmit Data-/Receive Data-(TRD-)