DNT-T103 & DNT-T221 Application Guide
Page 18 of 41 Document Edition 4.1
4. RESET ACTION (RESET RATE IN REPEA TS PER HOUR)
If the Reset Rate is non-zero, reset action is enabled. As long as there is a difference (or error) between
the input value (i.e., space temperature) and setpoint value, reset action will increment or decrement the
Controller Status value (AV14) over time - in proportion to the value of the reset rate and the magnitude
of the error - in an attempt to remove the error. In this way, the Controller Status value is continually
fluctuating in order to reach setpoint.
The amount of reset does not decrease internally as the input value approaches setpoint, but the reset
value is frozen while in deadband. The only time reset action has no affect on the controller output is
when the input is equal to the setpoint (no error). For this reason, be cautious about applying too much
reset action, otherwise you may cause unnecessary movement on actuators. By setting Reset Rate to 0,
you disable reset action altogether.
SETPOINTS
The BACstat II uses a series of setpoints for various purposes, most of which interact with one
another. For a complete list of these setpoints and other objects and their defaults, refer to the
Object table on page 9. When you change the units setting between ºC and ºF all of these
setpoints revert back to their matching default values – the BACstat does not do a conversion on
the fly. What follows hereafter is a working description for each of these setpoints. If the
particular setpoint is settable in the Configuration Menu it is indicated with its LCD text.
Day Setpoint (AV6) –
This is the setpoint used when in DAY mode. With the Display Code (AV15) set to an appropriate
value the setpoint can be adjusted up or down by pressing the buttons. Whether or not this
setpoint is displayed or is adjustable on the LCD, it is used internally for control. The units for the
setpoint are ºC or ºF (as per AI1) unless the second digit of the Display Code (AV15) is set to 3
(for Humidity), in which case the units become %RH. The value for Day Setpoint can also be set
in the Configuration Menu, or by commanding the variable (via GCL+ or ORCAview OWS or 3
rd
Day Minimum Setpoint (AV7) –
Party devices).
This is the minimum value a user can adjust the Day Setpoint to. If an attempt is made to adjust
the Day Setpoint lower, it will not change. If a lower value is commanded from the OWS or
another device, it will not accept the change. The value for Day Minimum Setpoint can be set in
the Configuration Menu, or by commanding the variable (via GCL+ or ORCAview OWS or 3
rd
Day Maximum Setpoint (AV8) –
Party devices).
This is the maximum value a user can adjust the Day Setpoint to. If an attempt is made to adjust
the Day Setpoint higher it will not change. If a higher value is commanded from the OWS or
another device, it will not accept the change. The value for Day Maximum Setpoint can be set in
the Configuration Menu, or by commanding the variable (via GCL+ or ORCAview OWS or 3
rd
Party devices).
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