Chapter 3: Option Selection
Operation of the serial communications section is determined by jumper installation as described
in the following paragraphs. Locations of the jumpers are shown in Figure 3-2, Option Selection at
the end of this section of the manual.
232/422
Jumpers must be installed in these blocks for each COM port. The function of the 232 and 422
jumpers is to configure the port for single-ended RS232 communications or differential
RS422/485 mode communications.
Echo
This jumper enables local echoing of transmitted characters back to the receiver. It is used to
confirm (locally) that a character was transmitted and may be installed for two-wire half-duplex
RS485 mode.
Auto or RTS
Only one jumper may be installed for each COM port. These jumpers select either the
AUTOMATIC or RTS line control modes for RS485 operation. To operate with Windows
programs, select AUTOMATIC.
120
1K
1K
+5V
Rx+
Rx-
LD
BIAS
BIAS
Figure 3-1:
Simplified Termination Schematic
Manual PCI-COM-2S
11
