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

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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	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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Contents Installation and Operation Tracer ZN521 Zone Controller Page CNT-SVX07C-EN April CNT-SVX07C-EN Tracer ZN521 Zone Controller Installation and Operation CNT-SVX07C-EN Contents Sequence of operations Status indicators for operation and communication Troubleshooting Index Overview and specifications Product descriptionClearances DimensionsStorage environment Plastic-cover model dimensions and clearances Agency listing/compliance Additional componentsZone humidity sensor Tracer zone temperature sensor optionsDamper actuators CO2 sensorOverview and specifications Input/output terminal wiring AC-power wiringGeneral wiring information Communication-link wiring and addressing General wiring information Location recommendations Operating environment requirementsMounting recommendations Mounting the Tracer ZN521 zone controllerControlValve Economizing Typical applications for the Tracer ZN521 zone controllerApplication SpeedfanMultiple Dehumidification HeatElectricBI2 Condensate overflow BI1 Low-coil-temperature detectionBinary inputs Binary inputsBI3 Occupancy or generic binary input BI4 Fan statusGND Ground terminals ZN Zone temperatureAnalog inputs Analog inputsSET Local setpoint FAN Fan mode inputAI1 Entering water temperature AI2 Discharge air temperature AI3 Outdoor air temperature or generic temperatureAI4 Universal 4-20 mA AI4 configuration options and associated measurement rangesConfiguration Measurement range AI4 terminal wiring CO2 measurement Binary output functions Binary outputsGeneric binary output Binary output FunctionsRequired controller inputs for proper operation Wiring requirements and optionsOverriding binary outputs Function Input source For more information SeeTwo-pipe hydronic-cooling unit Two-pipe hydronic-heating unit Two-pipe hydronic heating/cooling unit with auto changeover Four-pipe hydronic heating/cooling unit Four-pipe heating/cooling unit with auto changeover Two-pipe heating unit with DX cooling Electric heat unit with DX cooling Electric heat unit Two-pipe heating unit with face-and-bypass damper Two-pipe heating/cooling unit with face-and-bypass damper Four-pipe heating/cooling unit with face-and-bypass damper Input/output functions and wiring for typical applications Power-up sequence Random startOccupied standby mode Occupied modeUnoccupied mode Occupancy modesOccupied bypass mode Timed override controlSimplified zone control Zone temperature controlCascade zone control Morning warm-up Heating or cooling modeDischarge air tempering Morning cool-downEntering water temperature sampling function Fan operationExhaust control Exhaust controlModulating valve calibration Valve operationModulating valve operation Valve control optionsIsolation-valve operation Modulating outdoor/return air dampersTwo-position valve operation Two-pipe operationModulating outdoor air damper position Economizing free cooling Ashrae Cycle 1 conformanceAshrae Cycle 2 conformance DX cooling operation Two-position control of a modulating outdoor air damperFace-and-bypass damper operation Face-and-bypass, isolation-valve operationDehumidification Electric heat operationBaseboard heat operation Peer-to-peer communication Unit protection strategiesFan off delay Smart resetLow-coil-temperature protection Condensate overflowFreeze avoidance Filter-maintenance timerFreeze protection discharge air temperature low limit Test button Tracer ZN521 zone controller circuit boardManual output test For non OutputClose damper, air Outdoor Open damper, air Outdoor Step Result BOP1 BOP2 BOP3 BOP4 BOP5 BOP6 BOP7 BOP8 BOP9Interpreting LEDs Service pin buttonRed LED Service indicator LED activity ExplanationGreen LED Status indicator Yellow LED Communications indicatorDiagnostics Types of diagnosticsDiagnostic Probable cause Consequences Type Table of diagnosticsDiagnostics Fan unaffectedValved unaffected PositionDamper unaffected Status indicators for operation and communication Fan does not energize Probable cause ExplanationTroubleshooting Valves remain closedValves remain open DX or electric heat does not energizeOutdoor air damper remains closed Outdoor air damper remains openOutdoor air damper remains open Troubleshooting Index NumericsIndex Index Index Page Trane