Metasys System Extended Architecture (MSEA)
JCI MSEA, BACnet
This article describes how to create an advanced interlock to allow control to be easily switched from Events2HVAC to default JCI MSEA schedules in the event of a problem with the Events2HVAC server. These steps should be performed by a JCI technician or a qualified MSEA operator.
This article takes the following as given:
- The existing schedule object (Bldg Schedule) is controlling binary values BV1, BV2, BV3, and BV4 at priority 15.
- Events2HVAC is directly commanding the same BV points at priority 14. No other applications or programs are using priority 14 to send commands to those points.
- The user needs an easy way to release all BV points of priority 14 commands to revert back to the default JCI schedules in the event of an emergency.
- The new mode point will be called E2H_MODE and will have states OFF = 0, AUTO = 1.
Completing all the steps in Part 1 and Part 2 below will create a new binary value (BV) object called E2H_MODE that will do the following:
- When E2H_MODE is OFF, send a release priority 14 to all points that are being controlled directly from Events2HVAC. This will allow commands from JCI at priority 15 to take control. (Caution: All equipment will return to the state of the next highest priority in the priority array. If the default schedules want the unit OFF and an event is currently in progress, that system will be shutdown.)
- When E2H_MODE is AUTO, do nothing. Any commands coming from Events2HVAC will be commanded at priority 14.
Part 1: Create the Binary Value Mode Switch
1. From the main menu in the JCI Metasys software, select Insert > Object...
2. Select "BV" (Binary Value).
3. Select the "Programming" folder as the location to store the new BV.
4. Give the BV an appropriate name, such as 'E2H_MODE'
5. Enter an appropriate description for the new BV, and select the appropriate States Text ('Off Auto') and Default State ('Auto').
Now you have a new BV point to set the E2H_MODE value. Follow the steps in the next section to create an interlock that will trigger off the BV point to release Priority 14 on all points at once.
Part 2: Create the Interlock
1. From the JCI Metasys software main menu, select Insert > Object...
2. Select "Interlock".
3. Enter an appropriate description.
3. Give the interlock an appropriate name, such as 'E2H_Interlock'.
4. Select the "Programming" folder as the location of the new interlock.
5. Select the Interlock Definition tab, and click on the Add button.
6. Select the E2H_MODE binary value object that you created earlier. This will be the trigger for the interlock.
7. Select the correct state of the E2H_MODE object to trigger the actions.
8. Add actions to the False condition in the Action Tables tab. When the E2H_MODE logic in the previous screen = FALSE (NOT IN AUTO), the interlock will trigger the release of priority actions.
9. Select the items that you want to release the priority value on. This should be a list of all the end points that Events2HVAC is controlling (in this example, BV1-4).
10. After the points are added, the commands for each will need to be changed to release priority 14. Click on the grey button for each.
11. Select "Release", "Present Value" at priority "14".
12. Repeat for all items. Final settings should look like this:
13. In the All Items view, you should see both the new interlock and the new BV point that was created.
14. Right-click on the E2H_MODE object and test the interlock by sending an OFF command.
15. Verify that the items controlled don't have a value in the priority 14 slot of the priority array.
16. Double-click on BV1, select the "Advanced item" radio button, and click on the Priority Array dropdown menu:
17. Verify that the priority 14 slot is empty. The next-highest priority, priority 15, should be the active value.