122
Andover Controls
Normally Open Supervisory Inputs
NO Series
With this type of input wiring, a resistor is placed in series with the input. When the door
switch is open (normal position) the door is assumed to be closed. The circuit presents a
reading of 10K ohms at the input.
This circuit is not recommended!
Circuit Action Input Senses Condition
Switch Closed External Resistance Door Open
Switch Opened Infinite Resistance Door Closed
Wire Cut Infinite Resistance Door Closed
Input Shorted Zero Ohms Violation or error
When the door is opened the switch closes and the external resistance is measured.
Shorting the input causes a zero ohm reading which should result in an error condition.
Cutting the wire causes it to look like a normal “door closed” condition. In this case the
door could be forced open and the system would not detect the change in condition.
AUX
or
DOOR
or
REX
RET
Contact
Closure
External
Resistor
10 K
Ω
typical
AC-1
Technical Manuals Online! - http://www.tech-man.com
To Next Page
Loading...