Operational space temperature - Johnson Controls - LIT-12011950 - Building automation software - Smart Equipment Controller - 5.0

Smart Equipment Controls Sequence of Operation Technical Bulletin

Brand
Johnson Controls
Product name
Smart Equipment Controller
Document type
Technical Bulletin
Document number
LIT-12011950
Version
5.0
Revision date
2024-06-06
Product status
Active
Language
English

Related data and inputs

The related data and inputs include the following items:

  • Operational space temperature (OprST)
  • Space temperature source (STSrc)
  • Network override space temperature (NetST) communicated input on FC bus
  • Net sensor space temperature value to SA bus
  • Space temperature input (ST) to ST and COM
  • Return air temperature input (RAT) to RAT terminals.
  • Net sensor calibration (NS-Calibration) applies an offset to the net sensor space temperature.

Operation

The operational space temperature (OprST) uses the assigned priority levels for inputs ranked from highest to lowest in the following order:

  1. Network override space temperature (NetST)
  2. Net sensor space temperature value
    Note: If multiple sensors are connected, the average value is used.
  3. Space temperature input (ST)
  4. Return air temperature input (RAT)

If the input in use becomes invalid, operational space temperature (OprST) reverts to the next highest priority input.

When Single Setpoint mode is enabled, the control automatically determines if it is in heating or cooling mode. If the zone temperature exceeds the Common Setpoint, cooling or heating (depending on mode of operation) are initiated. The control changes between heating and cooling mode if the zone temperature exceeds the Common Setpoint +/- the Auto Changeover.

The space temperature source (STSrc) describes the input in use for the operational space temperature (OprST), and the indications include the following items:

BAS Override
Indicates the network override space temperature (NetST)
Network Sensor
Indicates a NetSensor
Local Input
Indicates a space temperature input (ST)
Return Air Temp
Indicates the return air temperature (RAT)
Unreliable
Indicates no valid input is available for the operational space temperature (OprST) and the control functions that use the OprST are not permitted

The network override space temperature is used if a value is set or communicated within the last 15 minutes. If 15 minutes pass without a communicated value, the UI displays Value Timed Out and the next highest priority input is used.

The net sensor space temperature value is used after approximately 30 seconds from the time a net sensor with space temperature capability is connected to the SA Bus.

Space temperature input is used if the temperature sensor is connected to the ST and COM terminals.

Return air temperature input is used if the temperature sensor is connected to the RAT terminals.