Analog inputs
SET: Local setpoint
The SET analog input functions as the local (hard-wired) temperature setpoint input for applications utilizing a Trane zone sensor with a tem- perature setpoint thumbwheel. The local setpoint input is configurable (as enabled or disabled) using the Rover service tool. A setpoint value communicated by means of a LonTalk link can also be used for controllers operating on a BAS. If both hard-wired and communicated setpoint val- ues are present, the controller uses the communicated value. If neither a hard-wired nor a communicated setpoint value is present, the controller uses the stored default setpoints (configurable using the Rover service tool). If a valid hard-wired or communicated setpoint value is established and then is no longer present, the controller generates a Setpoint Failure diagnostic.
FAN: Fan mode input
The FAN analog input functions as the local (hard-wired) fan mode switch input for applications using the Trane zone sensor with a fan mode switch option. The various fan mode switch positions (off, low, medium, high, auto) provide different resistances that are interpreted by the Tracer ZN521. The local fan mode switch input is configurable (as enabled or disabled) using the Rover service tool. A communicated fan mode request via the LonTalk communications link can also be used for controllers operating on a BAS. If both hard-wired and communicated fan mode values are present, the controller uses the communicated value. If neither a hard-wired nor a communicated fan mode value is present, the controller recognizes the fan mode value as auto and operates according to the default configuration. If a valid hard-wired or communicated fan mode value is established and then is no longer present, the controller generates a Fan Mode Failure diagnostic.
AI1: Entering water temperature
The AI1 analog input functions as the local (hard-wired) entering water temperature input. An entering water temperature communicated via the LonTalk communications link can also be used for controllers operating on a BAS. If both hard-wired and communicated entering water tempera- ture values are present, the controller uses the communicated value. If a valid hard-wired or communicated entering water temperature value is established and then is no longer present, the controller generates an Entering Water Temp Failure diagnostic.
For units configured as 2-pipe or 4-pipe changeover units, the entering water temperature is used to make heating/cooling operation decisions. If neither a hard-wired nor a communicated entering water temperature value is present on changeover units, the controller will always operate in heating mode.