5.1.1 Power LED indicator
When the data logger is powered, the Power LED will turn on according to power and program
states:
l
Off: No power, no program running.
l
1 flash every 10 seconds: Powered from BAT, program running.
l
3 flashes every 10 seconds: Powered via USB, program running.
l
Always on: Powered, no program running.
5.2 Power output
The data logger can be used as a power source for communications devices, sensors and
peripherals. Take precautions to prevent damage to these external devices due to over- or
under-voltage conditions, and to minimize errors. Additionally, exceeding current limits causes
voltage output to become unstable. Voltage should stabilize once current is again reduced to
within stated limits. The following are available:
l
Continuous 12 V: BAT + and – provide a connection to the unregulated, nominal 12 VDC
battery. It may rise above or drop below the power requirement of the sensor or peripheral.
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SW12: program-controlled, switched 12 VDC terminal. It is often used to power devices
such as sensors that require 12 VDC during measurement. Voltage on a SW12 terminal will
change with data logger supply voltage. CRBasic instruction SW12() controls the SW12
terminal. See the CRBasic Editor help for detailed instruction information and program
examples: https://help.campbellsci.com/crbasic/cr300/ .
l
VX terminals: supply precise output voltage used by analog sensors to generate high
resolution and accurate signals. In this case, these terminals are regularly used with
resistive-bridge measurements (see Resistance measurements(p. 95) for more
information). Using the SWVX() instruction, VX terminals can also supply a selectable,
switched, regulated 3.3 or 5 VDC power source to power digital sensors and toggle control
lines.
l
C, SE 1-4, and P_SW terminals: can be set low or high as output terminals (SE 1-4 and P_SW
to 3.3 V, and C to 5 V). With limited drive capacity, digital output terminals are normally
used to operate external relay-driver circuits. Drive current and high-state voltage levels
vary between terminals. See also Digital input/output specifications(p. 248).
See also Power requirements(p. 240).
5. Wiring panel and terminal functions12
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