B-1
Appendix B. 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 labe
l
ling 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 label
l
ing for the RS-422/RS-485 functions has also been changed to avoid
the confusion caused by different labe
l
ling 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 labe
l
ling, with the
TD–
and
TD+
pair being those used for RS-485 half-duplex connections. Please refer to
for a cross comparison between the connections for the
SDM-SIO1 and the SDM-SIO1A.
TABLE B-1. Pin Cross Connection Table for
SDM-SIO1 to SDM-SIO1A
SDM-SIO1
SDM-SIO1A
Case Text
Pin
Pin
Case Text
C1
1
3
C1
C2
2
4
C2
C3
3
5
C3
G
4
2
G
+12V
5
1
+12V
G
6
7
G
RX-A
7
10
Rx/RD+
CTS-B
8
11
CTS/RD–
RTS-Y
9
8
RTS/TD+
TX-Z
10
9
Tx/TD–
0V
11
6
RG
Z
12
9
Tx/TD–
Y
13
8
RTS/TD+
B
14
11
CTS/RD–
A
15
10
Rx/RD+