This module controls a single proportional source that is dynamically switched from a heating (winter) to a cooling (summer) mode. It also supports a discharge low limit for the heating mode. The module accepts as inputs a summer/winter changeover, cooling mode, heating mode, process variable, limit variable, cooling setpoint, heating setpoint, limit setpoint, and configuration information. The module outputs a cooling percent command, heating percent command, percent command, cooling control status, and a heating control status. 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 a second output that incorporates lead compensation to control devices. This function attempts to remove some of the dynamics of the control loop. This process results in forward-looking predictions and speeds up controller responses. The effect is similar to adding derivative action to the controller. Lead compensation is incorporated into most zone temperature control processes where oversized or nonlinear valves might be applied. For more information on the Lead Compensator block, see Lead Compensator in the Control category of the Logic section.
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.