Primary States (Heating Sequenced Valves with Low Limit) - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 16.0

Controller Tool Help

Brand
Johnson Controls
Metasys
Product name
Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
16.0
Revision date
2023-10-02
Language
English
  • Off: Turn everything off. The two valves are set to 0%.

  • Max: Open the two heating valves to 100%.

  • Hold: When commanded to this mode of operation, the module outputs retain their last values.

  • Limited Max: The valves are opened to the Limited Max Value. This state may be used for unoccupied heating.

  • T Control: The two valves are modulated in sequence to maintain the Process Variable at the Setpoint. The Percent Cmd is adjusted between 0% and 100% showing the total capacity percent used at any given time. The valves are modulated from 0% to 100%.

  • LL-T Control: The two valves are modulated in sequence to maintain the Low Limit Process Variable at the Low Limit Setpoint. The Percent Cmd is adjusted between 0% and 100% showing the total capacity percent used at any given time. The valves are modulated from 0% to 100%.

  • Low OA Temperature: When the OA Temperature is less than the Low OA Temperature Setpoint the valves are opened to the Low OA Temperature Position.

  • Failsoft: The valve is opened to the Failsoft Value. This state may be used when the control temperature is unreliable.

  • Low OA Temperature Startup: This mode activates the T Control state section, but limits the rate at which the valve can close so that the unit can safely come into control (typically used for 100% OA units with low OA temperatures at startup).

  • Remain In Control: Modulate the valve to control the Limit Variable to the Limit Setpoint. If the Limit Variable is reliable, the module controls the output to maintain the Limit Variable at the Limit Setpoint. This mode should only be used as a shutdown strategy to add energy to the duct when the fan is off. It should not be used for general temperature control.

Table 1. Heating Sequenced Valves with Low Limit Command Hierarchy

Low Limit Process Variable isReliable

Mode

OA Temperature isReliable

PID Tuning Reset

State

*

Off

*

*

Off

Max

*

*

Max

T Control

*

*

T Control

LL-T Control

*

*

LL-T Control

Hold

*

Reset 1st PID

T Control

Hold

*

Reset 2nd PID

LL-T Control

Hold

*

*

Hold

Low OA Temperature

True

*

Low OA Temperature

Low OA Temperature

False

*

Failsoft

Limited Max

*

*

Limited Max

Failsoft

*

*

Failsoft

Low OA Temperature

*

*

T Control

True

Remain In Control

*

*

Remain In Control

False

Remain In Control

*

*

Failsoft