Trane Tracer ZN.520 Manual page 48

When the controller is in unoccupied
mode, it always uses the stored
unoccupied heating and cooling setpoints.
46
Sequence of operation
I Occupancy mode
I Heating or cooling mode
I Setpoint high and low limits
When a building autoation system or other controller communicates a setpoint
to the controller, the controller ignores the hardwired setpoint input and uses
the communicated value. In unoccupied mode, the exceptio, the controller
always uses the stored default unoccupied setpoints.
After the controller completes all setpoint calculations, based on the requested
setpoint, the occupancy mode, the heating and cooling mode, and other
factors, the calculated setpoint is validated against the following setpoint limits:
I Heating setpoint high limit
I Heating setpoint low limit
I Cooling setpoint high limit
I Cooling setpoint low limit
These setpoint limits only apply to the occupied and occupied standby heating
and cooling setpoints. These setpoint limits do not apply to the unoccupied
heating and cooling setpoints stored in the controller's configuration.
Unit configuration also exists to enable or disable the local (hardwired)
setpoint. This parameter provides additional flexibility to allow you to appy
communicated, hardwired, or default setpoints without making physical
changes to the unit.
Table 31 Setpoint operation
Method Used in the following situations
Zone sensor (with an A hardwired, adjustable setpoint is connected to the controller.
adjustable hardwired Local setpoints are enabled in the unit configuration. No
setpoint) communicated setpoint is present.
Communicated source A setpoint is communicated to the zone controller, typically
from a building automation system or a peer controller. If both
a hardwired setpoint and a communicated setpoint exist, the
controller uses the communicated value. The configuration
feature for enabling/disabling the local setpoint does not affect
the setpoint handling when communicated setpoints are used.
The communicated setpoint always takes priority over the
hardwired setpoint, even when the local setpoint is enabled.
Stored default setpoints The controller uses the locally stored default heating and
cooling setpoints when neither a local hardwired setpoint nor
communicated setpoint is present. The controller uses stored
default setpoints when only a local setpoint exists, but the
local setpoint is disabled in the configuration of the controller.
The controller always uses the stored default (unoccupied)
setpoints in unoccupied mode.
CNT-SVX04A-EN