Campbell SDM-SIO1A, Instruction Manual

Page: 20 / 44

SDM-SIO1A and SDM-SIO4A Serial Input/Output Modules
10
If there is a need to insert more than one wire in each terminal, if using multi-
strand wire, twist the conductors together first. If using solid wires, solder or
crimp multiple pairs together before insertion.
TABLE 6-2 shows all the connections on the SDM-SIO1A.
TABLE 6-2. SDM-SIO1A Terminal Labels and Functions
Power SDM Communications Connections
12V G
C1
C2
C3
RG G R
TS
/T
D
+
T
x/
TD
–
Rx
/RD
+
CT
S/
RD
–
1 2 3 4 5 6 7 8 9 10 11
TABLE 6-3. SDM-SIO1A Functional Description of the Connections
Pin Case Text Connection To Description
1 12V
Datalogger
Power 12V
2 G Power supply 0V (same as other G pin)
3 C1 SDM data line
4 C2 SDM clock line
5 C3 SDM enable line
6 RG
1
Equipment
RG – RS-485 ground. Connected to G via 100 Ω 1 W resistor.
7 G
2
0V – (same as other G pin)
8 RTS/TD+
RS-232 RTS. RS-485 half duplex non-inverting.
RS-485 full duplex outgoing.
9 Tx/TD–
RS-232 transmit. RS-485 half duplex inverting.
RS-485 full duplex outgoing.
10 Rx/RD+
RS-232 receive. RS-485 receiver non-inverting.
RS-485 full duplex incoming.
11 CTS/RD–
RS-232 CTS. RS-485 receiver inverting.
RS-485 full duplex incoming.
1 Connection RG (pin 6) has a 100 Ω resistor in series with the datalogger ground
connection. This connection should be used when connecting RS-485 equipment by
long wire lengths. It ensures both systems have a common ground reference point. See
Section 2 , Precautions
(p. 2)
, before connecting.
2 The G (pin 7) can be used for the RS-232 zero volt reference or any other ground
connection needed, for example, shields.
The SDM-SIO4A has identical wiring for the datalogger connections (pins 1 to
5). To allow for the extra serial ports, pins 6 to 11 are reproduced four times,
once for each port. The connections for different ports are clearly delimited,
with each label
l
ed with the port number as a single large digit, that is, 1, 2, 3,
4.