What is a Computed Point?

This guide provides information about how Computed Points in the Resolute software work and provides operational parameters for every Computed Point available through the Resolute platform.  

What is a Computed Point? 

A Computed Point is a function that processes time-series data from at least one input point to calculate data for a new output point. There are two types of Computed Points – Computed Point Templates and Custom Computed Points. 

Every Computed Point Template (CPT) is designed to be applied to one type of equipment but can accept inputs from other Assets in the building hierarchy to calculate output data. Inputs can only be accepted if they fall under the applied equipment in the Asset path. For example, a CPT applied to an AHU can use input points from a child VAV equipment. However, it could never accept input points from equipment set as the Chiller. 

Some CPT’s can be more specific and require a particular type of equipment to have a definite set of tags. These specific tags for equipment types are noted as Equipment Meta Tags. If the required equipment tags are missing, these are referred to as the Equipment Tag Constraints. 

What are the Inputs to a Computed Point Template? 

While each CPT is defined to accept a different set of inputs, all inputs to these CPT’s fall into two broad categories: 

• Time-series data in the form of mapped input points   
• Configurable constants 

What are Standard Input Points? 

Every CPT requires at least one input point. A Standard Input Point uses a Resolute connector (such as Niagara) to retrieve time-series data at regular intervals. When a point is generated by applying a CPT to a piece of equipment, it can only be used as an input for the designated CPT. 

When a CPT is applied to any given equipment, the inputs for that Template are selected based on the following criteria: 

• The tags associated with a given Mapped Point. An occurrence of this would be a CPT that calculates the Zone Temperature Deviation will require an input with the “ZoneTemp” CPT assigned to it. 
• The position of the mapped point in the building hierarchy relative to the equipment that the CPT is attached to. Most CPT’s stipulate that an input point must be a child of the same equipment the CPT it will be applied to. In the case of a Zone Temperature Deviation Template, we would look for a Mapped Point with the “ZoneTemp” CPT attached to it that is also a child of the equipment that the CPT is attached to. Some CPT’s will have more complex positional requirements for their input points and can be children of the equipment in the Asset hierarchy. 

What are Mandatory Versus Optional Standard Input Points? 

For the CPT to be applied to the equipment it must have at least input, in the form of a suitable Mapped Point, this is the Mandatory Input Point. For example, the Template Zone Temperature Deviation can be applied to an AHU and only one input is required – a mapped point with the “ZoneTemp” CPT. If that AHU has a mapped point with the “ZoneTemp” CPT attached to it, then the CPT can be applied. If the required CPT is not applied to a Mapped Point under the AHU, then a candidate of the Computed Point will not be generated for that AHU by the platform. 

Some CPT’s may have one or more Input Points that are defined as optional. This means that, if a suitable Mapped Point cannot be found (based on matching criteria described above) for given equipment, a candidate of the Template can still be generated and applied to that equipment. Optional Input Points are typically used to refine the accuracy of a given calculation when they are present. 

Certain CPT’s will have more complex requirements around the presence or absence of different input points. For example, a CPT might stipulate that it requires either an “EffCoolSP” point or an “EffHeatSp” point. Taken by themselves, each of these points are optional, but the CPT cannot be applied unless at least one of these input points is present. These requirements are known as Tuple Constraints and define the presence or absence of more than one Input Point. 

What is Input Point Multiplicity? Scalar Versus Vector 

A Scalar Input Point is defined that there is only a single match that can exist. A Vector Input Point can have more than one match and all matches are used to calculate the output point. 

Most CPT’s are defined in such a way that only a single match can exist for a given input point. For instance, if a CPT expects that an AHU will have a single Mapped Point with the “ZoneTemp” CPT attached to it, and if more than one “ZoneTemp” point is found for that AHU, then the CPT cannot be applied to the AHU. This is because the CPT was expecting a single “ZoneTemp” input, and it does not know what to do with multiple “ZoneTemp” points. 

What are Configurable Constants? 

Most CPT’s define one or more constant that can be used to adjust the formula of a CPT. The Zone Temperature Deviation CPT, for example, defines one constant that is used to represent the “Temperature Deadband” and another constant to represent the “Occupied Value”. Each of these constants will be automatically assigned a reasonable default value when the CPT is applied to given equipment, but these values can be overridden by the user to adjust the formula for that piece of equipment for any reason. 

What are Mandatory Point Templates for Computed Point Output? 

Some CPT’s may have an output point with a pre-determined Point Template. These CPT’s can only be attached to equipment that do not have children points of the same CPT type. For example, a “ZoneTempDev” CPT cannot be applied to an AHU that already has a “ZoneTempDev” tagged Mapped Point.