Connect Tech NT960/PCI - Manual (Page 70)

4-18 Chapter 4: Appendix D - RS-485/422 Option
Intellicon-NT960/PCI User's Manual, ver. 0.02
DIP switches S1, S2, S3, and S4 on the RS-485/422 SLIM allow
you to select a "generator station" load and a "receiver station"
load. The "generator station" is either the TxD or RTS signals.
The "receiver station" is either the RxD or CTS signals.
The RS-485 SLIM also offers you the additional functionality to
disconnect the RxD signal pair COMPLETELY from the load and
bias circuits. This allows you to "multi-drop" the RxD station on a
half duplex communication line. You select this option with
switch positions 3 and 4 on switch blocks S1, S2, S3, and S4.
Please refer to the following examples concerning this option and
their switch settings.
Examples:
1. The following example shows the RxD signal pairs on a
ACM/Flex16 port disconnected from the load and bias
circuits for multi-drop on a half duplex line.
switch blocks
S1, S2, S3, or S4
2. The following example shows the RxD signal pairs on a
ACM/Flex16 port connected to the load and bias circuits.
switch blocks
S1, S2, S3, or S4
Switch positions 1 and 2 on switch blocks S1, S2, S3 and S4
allow the "generator stations" (TxD and RTS) to have either no
load or a DC load of 150 ohms. Please refer to the examples
following for these configuration options and their switch settings.