Priority Summary and Automation
Automation is the purpose of Computrols Building Automation System (CBAS). It’s there to make sure that on a daily basis you don’t have to be deciding what pieces of equipment should be running and when. This includes the VAV’S, AHU’s Chillers, Boilers, and Pumps that are often automated within a Building Automation System. Automation uses Schedules, Logic and PIDS to achieve this goal by looking at conditions and commanding Outputs to keep the equipment running when it needs to. The “priority” column shows how the point has been commanded.
Some things, like setpoints, are usually not automated because an engineer or management person decides what the temperature should be in a space. When a point is commanded in CBAS by a person, the priority is shown as OPER and that means it is currently not automated. Depending on the priority of the automation programmed for the point, the OPER command priority should override the point.
In the above example, the Start/Stop (S/S) point for AHU 55 has been commanded to START by OPER. This means that typical automation sequences like a weekly schedule would not process and the point will stay START around the clock. Unless you have a reason to do this, you would typically want to click the point, then “AUTO” to release the point back to its normal programming/sequence of operation.
There is an easy way to see if points in the system have been overridden or just to determine what is commanding them. The feature is called Priority Summary and it resides on the Text View menu. In CBAS close whatever View you are currently in and click Text View then Priority Summary.
The submenu shows all of the possible Priorities in order from the lowest Priority, Schedule, at the top to the highest Priority, Logic 4 at the bottom. You can click any one of these to see a list of what points are currently being commanded by that particular Priority.
Click Operator and you will see all of the points that have been overridden. As mentioned before, many of these will be setpoints and that’s OK. If any aren’t setpoints, then click the Point and click Auto. That will clear the OPER Priority and if there is any automation programmed for that point, the Priority will change within a certain time. The evaluation time of a Logic can vary and Schedules only evaluate once a minute. If it doesn’t change, it might be because the conditions in a logic statement have not been met. The priority will not change just because there is Logic related to the point. The point has to be commanded by the Logic in order for it to change Priority, so until that happens, the Priority will remain empty. In the case of a Schedule, the point will be either On or Off by SCH priority within a minute of clicking Auto.
Checking the Priority Summary of your CBAS system on a regular basis can be a good way to make sure that your building is truly Automated.