driven interrupts, asynchronous communications and SDI-12 communications. A C terminal
configured for digital I/O is normally used to operate an external relay-driver circuit
because the terminal itself has limited drive capacity.
l
VX terminals can be set low or high using the PortSet() or SWVX() instruction. For
more information on these instructions, see the CRBasic help.
l
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:
If TimeIsBetween (0,10,60,Min)Then
SW12(1) 'Turn phone on.
Else
SW12(0) 'Turn phone off.
EndIf
5. Wiring panel and terminal functions17
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