Programmable logic control
The data logger can control instruments and devices such as:
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Controlling cellular modem or GPS receiver to conserve power.
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Triggering a water sampler to collect a sample.
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Triggering a camera to take a picture.
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Activating an audio or visual alarm.
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Moving a head gate to regulate water flows in a canal system.
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Controlling pH dosing and aeration for water quality purposes.
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Controlling a gas analyzer to stop operation when temperature is too low.
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Controlling irrigation scheduling.
Control decisions can be based on time, an event, or a measured condition. Controlled devices can be physically connected to C, or SW12 terminals. 
Short Cut A CRBasic programming wizard suitable for many data logger applications. Knowledge of CRBasic is not required to use Short Cut. has provisions for simple on/off control. Control modules and relay drivers are available to expand and augment data logger control capacity.
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C terminals are selectable as binary inputs, control outputs, or communications ports. These terminals can be set low (0 VDC) or high (5 VDC) using the
PortSet()orWriteIO()instructions. See the CRBasic Editor help for detailed instruction information and program examples:
PortPairConfig()instruction. -
SW12 terminals can be set low (0 V) or high (12 V) using the
SW12()instruction (see the CRBasic help for more information).
The following image illustrates a simple application wherein a C terminal configured for digital input, and another configured for control output are used to control a device (turn it on or off) and monitor the state of the device (whether the device is on or off).
In the case of a cell modem, control is based on time. The modem requires 12 VDC power, so connect its power wire to a data logger SW12 terminal. The following code snip turns the modem on for the first ten minutes of every hour using the TimeIsBetween() instruction embedded in an If/Then logic statement:
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