Campbell Scientific SDM-CD16S 16-Channel Solid State DC Relay Controller Module - Manual (Page 8)

SDM-CD16S 16 Channel Solid State DC Control Module
EXTERNAL
7 TO 48 VDC
+ —
SDM-CD16S DATALOGGER
GND
C1
C2
C3
Connection with External Supply
SDM-CD16S DATALOGGER
12 V
C1
C2
C3
GND
Connection with Datalogger Supply
FIGURE 3. Connection Block Diagrams
If the 21X power supply is used to power the SDM-CD16S Load Power, all
low level analog measurements (thermocouples, pyranometers, thermopiles,
etc.) must be made differentially. This is a result of slight ground potentials
created along the 21X analog terminal strip when the 12 V supply is used to
power peripherals. This limitation reduces the number of available analog
input channels and may mandate an external supply for the SDM-CD16S.
4. Installation
• The SDM-CD16S must be installed in an enclosure that provides a
pollution degree 2 environment (normally, only nonconductive pollution.
However, a temporary conductivity caused by condensation may be
expected). All Campbell Scientific enclosures meet this requirement.
• Use copper conductors only.
Cables connecting the terminals of the datalogger and
SDM device should be kept as short as possible to
minimize the risk of corruption of the signals and damage
from induced surges. Where long cable runs (>3 m) are
unavoidable and the cables run outside, some extra
protection may be required for the SDM control terminals.
Please contact Campbell Scientific for further advice.
When connecting wires to the SDM signal terminals,
please ensure they are at ground potential before making
the connection, e.g. by touching them to the earth terminal. CAUTION
4