Trane CNT-SVX07C-EN, Zone Controller Analog inputs, GND Ground terminals, ZN Zone temperature

Chapter 4 Input/output functions and wiring for typical applications

Analog inputs

The Tracer ZN521 controller includes seven analog inputs. Table 4 describes their functions. Each function is explained in the following paragraphs. For an explanation of the diagnostics generated by each ana- log input, see “Diagnostics” on page 58. For more information about how the controller operates, see Chapter 5, “Sequence of operations”

Table 4. Analog inputs

Analog input	Function
terminal label
ZN	Zone temperature
GND	Zone sensor common ground
SET	Local setpoint
FAN	Fan mode input
GND	Auxiliary ground
AI1	Entering water temperature
AI2	Discharge air temperature
AI3	Outdoor air temperature or generic temperature
AI4	Universal 4–20 mA

GND: Ground terminals

Use a GND terminal as the common ground for all zone sensor analog inputs.

ZN: Zone temperature

The ZN analog input functions as the local (hard-wired) zone temperature input. The controller receives the temperature as a resistance signal from a 10 kΩ thermistor in a standard Trane zone sensor wired to analog input ZN. A zone temperature value communicated by means of a LonTalk link can also be used for controllers operating on a BAS. When both a hard- wired and communicated zone temperature value is present, the control- ler uses the communicated value. If neither a hard-wired nor a communi- cated zone temperature value is present, the controller generates a Zone Temp Failure diagnostic.

The ZN analog input is also used to communicate timed override requests and cancel requests to the controller for applications using a Trane zone sensor with ON and CANCEL buttons.

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