Binary inputs
CNT-SVX05B-EN 27
Although the filter status switch is normally open, it is configurable (see
Table 13).
IN12: Exhaust fan status or coil defrost
Binary input IN12 can be configured either as an exhaust fan status
input or a coil defrost input.
Exhaust fan status
When configured as an exhaust fan status binary input, IN12 indicates
the presence of air flow through an exhaust fan associated with the con-
trolled air-handling unit. For Tracer AH540/541 applications, a differen-
tial pressure switch detects exhaust fan status, with the high side of the
differential being supplied at the outlet. During exhaust fan operation,
differential pressure closes the normally open switch and confirms that
the fan is operating properly.
A Low Exhaust Fan Air Flow diagnostic is detected during the following
two conditions:
• The controller is commanding the exhaust fan On and the status
switch is not in the closed position.
• The fan status switch does not close the binary input within two min-
utes of the controller commanding the exhaust fan On.
Although the fan status switch is normally open, it is configurable (see
Table 14 on page 27).
Coil defrost
Binary input IN12 can be configured as a coil defrost input. See “Coil
defrost” on page 24.
Table 13. Filter status input configuration
IN11 configuration Contact closed Contact open
Not used Clean Clean
Normally closed Clean Dirty
Normally open Dirty Clean
Table 14. Exhaust fan status binary input IN12 configuration
IN12 configuration Contact closed Contact open
Not used Normal Normal
Normally closed
Exhaust fan diagnostic
1
Normal
Normally open Normal
Exhaust fan diagnostic
1
1 A Low Exhaust Fan Air Flow diagnostic is generated when the controller turns on
the exhaust fan output, but the exhaust fan status binary input indicates the
exhaust fan is not running after a 2 minute time delay. This diagnostic is latching,
but it does not affect controller operation of the air-handling unit.
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