There are times when there are devices that need to be controlled by a CCU but are only available via BACNet control. Previously, this meant that we would not be able to control the RTU and would have to reject the project.
Using the Tridium software AXIOM (workbench) and a JACE (with IO) we are able to integrate the BACNet points and device of the RTU and perform the desired control using the analog outputs from the CCU to drive the logical control within the JACE.
See the attached drawings for a reference of what this solution looks like from our CDDs, and see the screenshots below that show the logical control with in the JACE.
Using the CCU Heating Loop Output, we calculate the correct heating discharge air temperature setpoint between the range of 71°F - 80°F.
Using the CCU Cooling Loop Output, we calculate the correct cooling discharge air temperature setpoint between the range of 50°F - 70°F.
After calculating the correct discharge air temperature setpoint, we will write this to the correct BACNet setpoint (Model, Manufacturer dependent) to engage heating or cooling, depending on the current conditioning mode the CCU is calling for.
Using the G Relay from the CCU, we engage the unit to be occupied via BACNet whenever the CCU calls for occupancy.
- The aforementioned problem is resolved and allows additional integration of BACNet points that would not have been previously available.