CNT-SVX08F-EN
21
Sequence of Operations/SCC Mode
will be placed in occupied bypass mode and remain in that mode until either the cancel button is
pressed on the Trane zone sensor or the occupied bypass time expires.
Output Types
The MP501 can be configured to control its actuator output in any one of three modes:
•
Tri-state modulating
•
Analog (default)
•
2-stage
Tri-state Modulating
In the tri-state modulating mode, binary output 1 is used to drive the actuator in the open direction
to provide more capacity (such as heating, cooling, or fan speed) and binary output 2 is used to
drive the actuator in the closed direction to provide less capacity.
When the PID loop creates a change in the actuator command, the controller determines how much
time to drive the open or closed outputs to on, in order to move the actuator to the desired position.
The actuator stroke time is configured so the controller can calculate these on times and determine
the position of the actuator.
The output defaults to 50% on power-up. Overdrive logic automatically calibrates the actuator at
the fully open and closed positions without continually driving the actuator.
This can cause
unnecessary wear
.
Analog
In analog mode, the controller uses the actuator command from the PID loop to calculate the
desired output voltage for the analog output. The minimum and maximum analog output values
are configurable to achieve the desired voltage output for a given command. The output minimum
can be set greater than the output maximum in order to accommodate a reverse acting output. For
example, a 6–9 Vdc actuator controls a valve where 9 Vdc closes the valve and 6 Vdc opens the
valve. In the configuration for the analog output, enter 9 Vdc for a PID output of 0% and 6 Vdc for
a PID output of 100%.
2-stage
In 2-stage mode, the controller turns on binary output 1 and binary output 2 in response to the
current output of the PID loop. Each binary output has a preset make-and-break limit to provide
hysteresis control so an output does not cycle on and off if the PID loop is calculating a value near
one of the limits. Refer to
.
