Appendix C. Matching Sdm-Sio1A Connections To An Sdm-Sio1 - Campbell SDM-SI01A Product Manual

Appendix C. Matching
SDM-SIO1A connections to an
SDM-SIO1
This section is provided for users who are familiar with the older SDM-SIO1, so they can cross
reference connections between the new and old devices.
The SDM-SIO1A has fewer terminals and different labelling than the SDM-SIO1. It does, however,
perform in exactly the same way and can be used as a drop-in substitute with only minor
changes to the wiring. It has fewer terminals because the Z, Y, B, and A terminals are not present.
For the SDM-SIO1 these terminals were connected internally to the Tx, RTS, CTS and Rx terminals
respectively and were, therefore, duplicates. RS-422 and RS-485 devices can be connected to the
equivalent multifunction terminals on the SDM-SIO1A.
The labelling for the RS-422/RS-485 functions has also been changed to avoid the confusion
caused by different labelling conventions used for the A and B terminals by different
manufacturers. To avoid this, the SDM-SIO1A uses the alternative TD–, TD+, RD–, RD+ scheme of
labelling, with the TD– and TD+ pair being those used for RS-485 half-duplex connections. Please
refer to Table C-1 (p. 39) for a cross comparison between the connections for the SDM-SIO1 and
the SDM-SIO1A.
Table C-1: Pin cross connection table for SDM-SIO1 to SDM-SIO1A
SDM-SIO1
Case text
C1
C2
C3
G
+12V
G
RX-A
Pin
1
2
3
4
5
6
7
SDM-SIO1A and SDM-SIO4A Serial Input/Output Modules
SDM-SIO1A
Pin
3
4
5
2
1
7
10
Case text
C1
C2
C3
G
+12V
G
Rx/RD+
39