Chapter 3 Input and Outputs
20 CNT-SVX05B-EN
The controller uses the IN5 value to determine if economizing (free cool-
ing) is feasible. For economizing to be allowed, economizing must be
enabled and the outdoor air temperature must be below the economizer
enable point (default 60°F, configurable). If the outdoor air temperature is
equal to or above the economizer enable point, or if there is no value is
present, economizing is not allowed. If both hard-wired and communi-
cated outdoor air temperature values are present, then the controller
uses the communicated value.
If a valid hard-wired or communicated outdoor air temperature value is
established and then is no longer present, the controller generates an
Outdoor Air Temp Failure diagnostic and economizing is no longer
enabled. If the sensor returns to a valid input, the controller automati-
cally clears the diagnostic and allows economizer operation.
IN6: Mixed-air temperature
Analog input IN6 is used for mixed-air temperature, with an averaging
1000 Ω (at 32°F [0°C]) RTD sensor only (see Table 75 on page 107). The
input is used for mixed-air tempering and outdoor air economizing opera-
tions.
The Tracer AH540/541 controller does not allow economizing if the con-
troller does not sense a valid mixed-air temperature input. If the sensor
returns to a valid input, the controller automatically checks to see if econ-
omizer operation is possible.
If a valid mixed-air temperature signal has been established by the RTD
sensor, but then the value is no longer present, the controller generates a
Mixed Air Temperature Failure diagnostic and disallows economizer
operation. When the sensor returns to a valid input, the controller auto-
matically clears the diagnostic and checks to see if economizer operation
is possible.
IN13: Universal analog input
The universal analog input IN13 (TB43) can be configured for a variety of
sensors using the Rover service tool (see “Configuration” on page 73). The
input must be configured properly for the sensor wired to the input. The
input can be used for only one sensor at a time. The following sensors are
supported:
• Space relative humidity (4–20 mA)
• CO2 sensor (4–20 mA)
• Entering water temperature (10 kΩ thermistor)
• Evaporator refrigerant temperature (10 kΩ thermistor)
• Generic temperature (10 kΩ thermistor)
Relative humidity
When using the universal analog input with a relative humidity sensor
first configure the controller input using the Rover service tool, and then
make the wiring connections. The sensor must provide a 4–20 mA signal
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