48
Andover Controls
Sensing Digital Inputs or Contact Closures
Digital input points are designed to provide an ON or OFF reading of a signal (wired
between the input and return).
To sense a digital input or contact closure, configure an input point with an Electrical
Type of
Digital
.
A digital input is considered “ON” whenever the voltage across its input meets or exceeds
the ON Threshold. For a contact closure, this is 0 (zero) volts. Similarly, an OFF condition
meets, or is lower than, the Off Threshold. With a contact closure, this is the value of
Vref.
Note
: When configuring a Digital point, there is a ‘Polarity’ attribute. If this attribute is
enabled, readings are reversed: ‘On’ will occur when the input is at Vref because the
contact is open, and ‘Off’ occurs when the input is at 0 volts because the contact is
closed.
Digital logic
Signal
IN x
RET
IN x
RET
Contact
Closure
DI-8
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