Chapter 3: Option Selection
To help you locate the jumpers described in this section, refer to the Figure 3-1, Option Selection Map on
the next page. Operation is determined by jumper installation as described in the following paragraphs.
485 and 422 Mode Jumpers
If you are going to operate in two-wire RS485 mode, install a jumper at the location labeled 485.
If you are going to operate in four-wire RS485 mode, install jumpers at the locations labeled 485 and 422.
If you are going to operate in RS422 mode, install a jumper at the location labeled 422.
Baud Rate Range Jumpers
The jumpers labeled Baud provide means to select baud rates in either of two ranges. When in the "1x"
position, the baud rate range is up to 115,200 baud. When in the "4x" position, the baud rate range is up
to 460,800 baud.
Note
Refer to Table 5-1, Baud Rate Divisor Values
Termination Jumpers
A transmission line should be terminated at the receiving end in its characteristic impedance. Installing
jumpers at the locations labeled TERMOUT (for two-wire RS485 mode) or TERMIN (for RS422 or four-
wire RS485 mode) applies a 120
Ω
load across the receive input.
120
0.1 F
Tx+/R x+
Tx-/R x-
JUMPER
:
Figure 3-1
: Simplified Termination Schematic
Where there are multiple terminals, only the ports at each end of the network should have terminating
impedance as described above. If this card is not to be at one end of the network, do not install the
jumpers as described above.
Also, there must be a bias on the TX+ and TX- lines. If the card is not to provide that bias, or if bias on the
RX+ and RX- lines is required, contact the factory for technical support.
Manual PCI-ICM-1S
10
