Primary States (Occupied Sequencing [AHU MASD]) - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 13.1

Controller Tool Help

Brand
Johnson Controls
Metasys
Product name
Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
13.1
Revision date
2019-12-04
Language
English
  • Satisfied: The sequencer is in this state if no heating or cooling is required. The transition to Satisfied normally requires the sequencer to be either in Preheat or Econ and the device to saturate low (or closed). To facilitate commissioning (when the Fast Sequence Enable flag is True), the sequencer goes out of any cooling state if the Cooling Setpoint increases by more than the Setpoint Threshold and the Process Variable is lower than the new Cooling Setpoint. Likewise, the sequencer goes out of any heating state if the Heating Setpoint decreases by more than the Setpoint Threshold and the Process Variable is lower than the new Heating Setpoint.

    The sequencer also might enter Satisfied from Mechanical Cooling if the Process Variable is less than the Cooling Setpoint and the cooling device is not responding to the sequencer. Likewise, the sequencer might enter Satisfied from Preheat if the Process Variable is greater than the Heating Setpoint and the preheat device is not responding to the sequencer.

  • Econ: The sequencer enters this state if cooling is required and the economizer is available. In this state, the damper controls the process variable.

  • Mech: The sequencer enters this state if cooling is required and the economizer is not available. In this state, the damper should close and the cooling device controls the Process Variable.

  • Econ + Mech: The sequencer enters this state if after being in Econ, the damper output controller is saturated open. In this state, the damper is open to its maximum position, and the cooling output controller controls the process variable.

  • Preheat: The sequencer enters this state if heating is required. In this state the preheat output controller controls the process variable.

  • Preheat + Reheat: The sequencer enters this state if after being in Preheat, the preheat output controller has saturated high. In this state, Preheat is set to its maximum position, and the reheat output controller controls the process variable. To transition back to Preheat the sequencer requires that the Process Variable is greater than the Heating Setpoint and either the reheat device saturate low or the Reheat Device is not responding to the sequencer.

  • Cooling Idle: The sequencer enters this state through Satisfied whenever it is enabled. In this state, all of the output controllers should hold their last command. This state is used to allow the fans to start and obtain an accurate reading of the Outdoor Air Temperature (and humidity if used) to determine the free cooling suitability.

  • Heating Idle: The sequencer enters this state through Satisfied whenever it is enabled. In this state, all of the output controllers should hold their last command. This state, in the DA-T Control Units, waits for the fans to start. In Zone control units, the state machine skips through to Preheat.

  • Temperature Unreliable: The sequencer enters this state if the process variable sensor is unreliable.