Campbell Scientific SDM-CD16AC 16-Channel ac/dc Relay Controller - Manual (Page 7)

SDM-CD16AC 16 Channel AC/DC Controller
EXTERNAL
9 TO 18 VDC
+ —
SDM-CD16AC DATALOGGER
12 V
GND
C1 or SDM-C1
C2 or SDM-C2
C3 or SDM-C3
Connection With External Supply
SDM-CD16AC DATALOGGER
GND
12 V
C1 or SDM-C1
C2 or SDM-C2
C3 or SDM-C3
Connection with Datalogger Supply
FIGURE 2. Connection Block Diagrams
If the 21X power supply is used to power the SDM-CD16AC, 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-CD16AC.
4. Installation
• The SDM-CD16AC 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.
• Wire Range: 30 − 14 AWG
• Tightening Torque: 5 − 7 in./lb.
• Use minimum 60/75 degree C wire.
• Input power must be connected to a class 2 supply only. All Campbell
Scientific power supplies meet the class 2 supply requirements.
3