Access PCI-COM422/4 Option Selection, Terminations, Data Cable Wiring, Baud Rate Ranges

Chapter 3: Option Selection

To help you locate the jumpers described in this section, refer to Figure 3-2, Option Selection Map at the end of this section. Operation of the serial communications section is determined by jumper installation as described in the following paragraphs.

Terminations

A transmission line should be terminated at the receiving end in its characteristic impedance. Installing a jumper at the locations labeled LDxO and LDxI apply a 120? load across the transmit/receive input/output for RS422 operation.

In RS422 operations where there are multiple terminals, only the RS422 ports at each end of the network should have terminating impedance as described above. To so terminate the COM A port, place a jumper at the location labeled LDAO. To terminate the COM B, COM C, and COM D ports, place jumpers at locations

labeled LDBO, LDCO, and LDDO
respectively. Similarly, inputs are terminated	Figure 3-1:Simplified Termination Schematic
at jumpers labeled LDAI, LDB1, etc.

Also, for RS422 operation, there must be a

bias on the Tx+ and Tx- lines. If the COM422/4 card is not to provide that bias, contact the factory technical support.

Data Cable Wiring

Signal	Pin Connection
TX+	2
TX-	3
RX+	9
RX-	1
Ground	5

Baud Rate Ranges

The jumpers labeled CLK X1 and CLK X4 provide means to select baud rates in either of two ranges. When in the "X1" position, the baud rate range is up to 115,200 baud. When in the CLK X4 position, the baud rate range is 200 to 460,800 baud.

Manual MPCICOM422-4.E1b Page 3-1