Attributes (Start Stop Sequencing [AHU 100% OA]) - 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

The following table describes the attributes used by the Start Stop Sequencing (AHU 100% OA) modules.

Table 1. Start Stop Sequencing (AHU 100% OA) Attributes

Name

Description

Default Value

Cooling Required

Indicates cooling demand. When this input is True, the Start/Stop module initiates a start up sequence.

False

Duct Static Pressure

Contains the value of the duct static pressure used by this module and passed to the Supply Fan Output controller.

Display Units: Pa, in. W.C.

Duct Static Pressure 1

Contains the supply air duct static pressure. The unit may have two pressure sensors. When the application has one pressure sensor, it must be connected to both Duct Static Pressure 1 and Duct Static Pressure 2.

0 Pa, 0.00 in. W.C.

Duct Static Pressure 2

Contains the supply air duct static pressure. The unit may have two pressure sensors. When the application has one pressure sensor, it must be connected to both Duct Static Pressure 1 and Duct Static Pressure 2.

0 Pa, 0.00 in. W.C.

Duct Static Pressure Setpoint

Contains the supply air static pressure setpoint. This input is used to trigger a state change if the supply fan type is variable speed and static pressure control is used.

250 Pa, 1.00 in. W.C.

Fan Ready

Indicates that the Start/Stop sequencer has reached the On State. The temperature control sequencers (such as the 100OA SD Sequencer or the 100OA CD Sequencer) use this information to allow DAT temperature sequencing.

 

Fan Start Delay

Contains the time delay provided from the time between issuing the start commands (supply and exhaust fans simultaneously) to expecting the fans to have started. This delay includes the time for the 2-position damper for each fan to open (that is, it assumes the damper is hard-wired with the fan starter).

90 Seconds

Fan Stop Delay

Time delay allocated to stopping the fans and closing the dampers. It also enforces a minimum time off before restarting.

240 Seconds

Heating Ramp Rate

Used to determine the time to remain in the Cold Start state (if applicable). During the Cold Start state, the preheat output is prevented from closing quickly allowing it to come into control without tripping the Low Limit on the unit.

20 Change per Minute

Heating Required

Indicates heating demand. When this input is True, the Start/Stop module initiates a startup sequence.

False

Low Limit Setpoint

Setpoint that determines whether Cold Start is necessary. When the OA Temperature is below this setpoint or is not reliable, the Cold Start mode is activated during Startup.

7 °C, 45 °F

OA Temperature

Contains the outdoor air temperature.

13 °C, 55 °F

Proof of Airflow

Shows the current airflow status. The output may be either True, False, or Fault. True means the fan was commanded on and airflow has been detected. False means the fan was not commanded on. Fault means the fan was commanded on, but airflow proof has not been detected. This input is used to restart the supply fan after a fan status fault.

True

Set Name: False/True/Fault

Stabilize Delay

Time allocated for the OA Temperature sensor to accurately reflect the outside conditions. It is only applicable for constant capacity units as it is assumed that the time required for ramping the variable capacity supply fan to the static pressure setpoint is sufficient for the sensor to stabilize.

180 Seconds

STARTSTOP-STATE (State)

Current state of the finite state machine. This output is connected to the state selection matrix.

Set Name: AHU 100 OA StartStop States

See Primary States (Start Stop Sequencing [AHU 100% OA]).

Supply Fan OnOff

Contains the control signal for the supply fan. The enumeration set only has two values, Off and On. The command signature of this input indicates if the supply fan is responding to this sequencer.

Off

Set Name: Off/On

Supply Fan Percent Cmd

Current value of the supply fan output.

0%

Supply Fan Type

Indicates the air handler supply fan type. The module supports two supply fan types, variable capacity, and constant capacity.

Variable Capacity

Set Name: AHU Supply Fan Type