Example: Using outside air temperature over BACnet references

The example includes 2 devices with 2 heating circuits each. When creating the control program, 4 heating circuits are taken from the library, each with an outside temperature sensor pre-programmed. Since there is only 1 physical temperature sensor on the outside wall, 3 heating circuits must be linked to the physical outside air temperature object via a BACnet reference object.

As the corresponding engineering takes place in ABT Site as well as in the field program editor, the order of the example must be observed.

Example:

 

1. Naming settings for I/O replacement

In order for the automatic replacement of the objects to work, the setting must first be checked or, if necessary, changed.

  1. Go to Settings.
  2. Open the Naming defaults task.
  3. Select the Plant automation tab.
  4. In the Naming settings for I/O replacement section:
    • From the Use I/O description of drop-down list, select Target (drop destination).
    • From the Use I/O name drop-down list, select Target (drop destination).

 

2. Creating devices

  1. Go to Building > Building structure.
  2. Define the first device.

Defining a building structure

Adding devices

 

3. Creating heating circuits 1 and 2 in the programming editor for device 1

  1. In the building hierarchy, select device 1.
  2. Right-click and select Go to programming.
  3. The Programming editor opens.
  4. Select the Library tab.
  5. Select a plant from Plants > Nested, for example, Hcr22x Heating circuit.
  6. Drag the selected plant into + Add plant in the Project tree.
  7. Rename the properties of the Heating circuit 1:
    a. Select the BACnet properties tab or right-click and select Properties..
    b. Select the Naming tab.
    c. In the Name field, replace the default name with a unique Name extension.

    d. In the Description field, replace the default name with a unique description.
  8. Repeat the steps 4 to 6 for heating circuit 2 or use the Duplicate function.
  9. In the Project tree, delete the default Plant.
  1. The heating circuits 1 and 2 in the device 1 are created.

 

4. Creating heating circuits 3 and 4 in the programming editor for device 2

  1. In ABT Site, go to Building > Building structure.
  2. In the building hierarchy, select device 1.
  3. Right-click and select Duplicate.
  4. The Add devices dialog box opens.
  5. Rename the Device name and the Device description name.
  6. Click OK.
  7. The device 2 with heating circuit 3 and 4 is created.
  8. Select the device 2 with heating circuit 3 and 4.
  9. Right-click and select Go to programming.
  10. The Programming editor opens.
  11. In the Project tree, right-click the Heating circuit 1 and select Properties.
  12. The Properties dialog box opens.
  13. Rename the properties of the Heating circuit 1 to 3:
    a. Right-click and select Properties.
    b. In the Name field, replace the default name with a unique Name extension.

    c. In the Description field, replace the default name with a unique description.
  14. Rename the properties of the Heating circuit 2 to 4.
  15. The heating circuits 3 and 4 in the device 2 are created.
info

After completing the control program for the 4 heating circuits, 4 outside air temperature sensors are got created. Since the building only has only 1 physical outside temperature sensor, 3 created sensors must get replaced by BACnet references to that physical sensor.

 

5. Creating a BACnet reference for heating circuit 2 in device 1

  1. In ABT Site, go to Building > Building structure.
  2. In the building hierarchy, select device 1.
  3. Right-click and select Go to engineering.
  4. Open the BACnet references task.
  5. Select the Projects tab.
  6. In the Projects area, expand the building hierarchy.
  7. Select the device 1 with Hcr 1 + 2.
  8. Filter for the outside air temperature data points:
    • In the column Name, enter TOa.
    • In the column Object enter AI.
  9. The data points for the outside air temperature of heating circuits 1 and 2 are displayed.
  10. Drag the data point from heating circuit 1 to the Plants navigation view of heating circuit 2, this will create a new BACnet reference in Heating circuit (2), referencing the outside air temperature of Heating circuit (1).

 

6. Creating a BACnet reference for heating circuit 3 and 4 in device 2

  1. In ABT Site, go to Building > Building structure.
  2. In the building hierarchy, select device 2.
  3. Right-click and select Go to engineering.
  4. Open the BACnet references task.
  5. Select the Hcr 3 + 4 tab.
  6. Select the Projects tab.
  7. In the Projects area, expand the building hierarchy.
  8. Select the device 1 with Hcr 1 + 2.
  9. Filter for the outside air temperature data points:
    • In the column Name, enter TOa.
    • In the column Object enter AI.
  10. The data points for the outside air temperature of heating circuits 1 and 2 are displayed.
  11. Drag the data point from heating circuit 1 to the Plants navigation view of heating circuit 3, this will create a new BACnet reference in Heating circuit (3), referencing the outside air temperature of Heating circuit (1).
  12. Drag the data point from heating circuit 1 to the Plants navigation view of heating circuit 4, this will create a new BACnet reference in Heating circuit (4), referencing the outside air temperature of Heating circuit (1).

 

7. Replacing the default I/O data point in the control program with the BACnet reference of device 1

  1. In the building hierarchy, select device 1.
  2. Right-click and select Go to programming.
  3. The Programming editor opens.
  4. In the Project tree, expand the BACnet folder of heating circuit 2.
  5. In heating circuit 2, drag the data point [ACalcValRef] Outside air temperature (1) over the data point [AI] Outside air temperature.
  6. The I/O replacement dialog box opens.
  7. All block names with a data point TOa are listed.
  8. Click Replace.
    Note: Selecting a data point is not necessary, the functionality replaces all listed data points.
  9. The data point [AI] Outside air temperature is replaced with the data point [ACalcValRef] Outside air temperature (1) (and the name is adjusted to Outside air temperature, without the extension (1)).
  10. The data point [ACalcValRef] Outside air temperature (1) is marked as assigned to the control program.
  11. The default data point information in the control program are replaced with the BACnet reference.
  12. The data point Outside air temperature from heating circuit 2 is deleted in the BACnet folder as in the TX & onboard I/Os folder.
  13. The data point Outside air temperature from heating circuit 2 is deleted from the Projects area of ABT Site as well.

 

8. Replacing the default I/O data point in the control program with BACnet reference of device 2

  1. In the building hierarchy, select device 2.
  2. Right-click and select Go to programming.
  3. The Programming editor opens.
  4. In the Project tree, expand the BACnet folder of heating circuit 3.
  5. In heating circuit 3, drag the data point [ACalcValRef] Outside air temperature (1) over the data point [AI] Outside air temperature.
    (picture see heating circuit 2)
  6. The I/O replacement dialog box opens.
  7. All block names with a data point TOa are listed.
  8. Click Replace.
    Note: Selecting a data point is not necessary, the functionality replaces all listed data points.
  9. The data point [AI] Outside air temperature is replaced with the data point [ACalcValRef] Outside air temperature (1).
  10. The data point [ACalcValRef] Outside air temperature (1) is marked as assigned to the control program.
  11. The default data point information in the control program are replaced with the BACnet reference.
  12. The data point Outside air temperature from heating circuit 3 is deleted in the BACnet folder as in the TX & onboard I/Os folder.
  13. In the Project tree, expand the BACnet folder of heating circuit 4.
  14. In heating circuit 4, drag the data point [ACalcValRef] Outside air temperature (1) over the data point [AI] Outside air temperature.
    (picture see heating circuit 2)
  15. The I/O replacement dialog box opens.
  16. All block names with a data point TOa are listed.
  17. Click Replace.
    Note: Selecting a data point is not necessary, the functionality replaces all listed data points.
  18. The data point [AI] Outside air temperature is replaced with the data point [ACalcValRef] Outside air temperature (1).
  19. The data point [ACalcValRef] Outside air temperature (1) is marked as assigned to the control program.
  20. The default data point information in the control program are replaced with the BACnet reference.
  21. The data point Outside air temperature from heating circuit 4 is deleted in the BACnet folder as in the TX & onboard I/Os folder.
  22. The data points Outside air temperature from heating circuit 3 and 4 are deleted from the Projects area of ABT Site.

 

Final result

Shows the data point situation in ABT Site (in the BACnet references task) and in the control program.

Device 1

Device 2