This module is responsible for outside air damper control. This module is used by two applications, the Unit Ventilator ASHRAE Cycle 3 zone control application and the Heat Pump application. When in the Control Limit mode, the module selects the minimum percent command from the normal control and the low limit control to position the OA Damper. The module accepts inputs in the form of a mode, process variable, setpoint, low limit process variable, and low limit setpoint. The module outputs a percent command and the control status based on the input mode and parameter settings. This module also incorporates tracking the overridden value of the actual output object (AO, PAO). The module resets the PIDs to default tuning parameters if the Reset PID Tuning input is not Normal.
This module provides EWMA diagnostic values calculated by the PID. Controllers have the ability to collect data about their inputs, outputs, and internally calculated variables. Inside the controller, the EWMA minimizes memory requirements, reduces communication traffic, and provides an easy way to analyze collected data. See EWMA Diagnostics in the Commissioning a System section for more information.