Campbell Scientific SDM-INT8 8-Channel Interval Timer - Manual (Page 11)

SDM-INT8 8 Channel Interval Timer
10K OHM
RESISTOR
CR800,
CR850,
CR9032
(CR9000X),
CR9080
(CR9000),
CR10(X),
CR23X,
or
CR1000
CR3000,
CR5000
12V
G
SDM-C3
SDM-C2
SDM-C1
FIGURE 3. Wiring Diagram
4. Power Supply Considerations
The datalogger's power supply is typically used to power the INT8, however,
an auxiliary supply may be used as shown in Figure 3. When selecting a
power supply, consideration must be given to the active current drain and the
active time of the INT8. With two exceptions, if the INT8 is programmed it is
drawing 13 to 20 mA. The two exceptions are:
• When the Specified Averaging Interval (Output Option Section 5.4) is
selected, the INT8 enters the quiescent current drain state (400 microamp
current drain) after returning the results to the datalogger.
• If the interval between executions of Instruction 101 exceeds 16.77
seconds, the INT8 enters the quiescent current drain state.
If a 21X datalogger is used to power the INT8, all low level analog
measurements (thermocouples, pyranometers, etc.) must be made
differentially. This is due to slight shifts in the ground potential on the
terminal strip when the 21X is used to power external devices.
5. Programming the Datalogger
The datalogger is programmed using either CRBasic or Edlog. Dataloggers
that use CRBasic include our CR800, CR850, CR1000, CR3000, CR5000, and
CR9000(X). Dataloggers that use Edlog include CR7, CR10(X), CR23X, and
21X. Both CRBasic and Edlog are provided in LoggerNet and PC400.
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