An Item owns a number of DataItems (called Item DataItems) related to the processing of Item Type data. The input is either raw meter data imported into storage, or data from any of the stages of processing other Items. Items outputs include a calculated value, a target value to compare the calculated value against, both the calculated vaue and the target value to a fiscal cost, and value high and low limits usually used for generating alerts.

Type DataItem Description
Raw RAW The Raw DataItem for this meter
Pre-processed PREP Performs unit conversion and aggregation calculations on the Raw data
Calculated CALC This contains the core Item value. It performs either an equation calculation on the Pre-processed data (Source Reference) or one or more other DataItems for other Items (Cross-reference)
Target TARGET Performs an equation calculation based on the time of the Item Calculated Data or Item Data Point List representing the ideal value to compare the Item Calculated DataItem value to.
Cost COST This contains the Meter Calculated DataItem values converted to a fiscal cost
Target Cost TCOST The Item Target DataItem converted to a fiscal cost
High and Low Calculated HCALC & LCALC Calculated limits that can be interpreted as physical constraints or alarm conditions if exceeded

The following diagram illustrates the DataItem dependency tree.


Cyclic Dependencies

A DataItem has a Cyclic Dependency when it is co-dependent with another DataItem. This mutual dependency relationship can be direct or indirect. For example, given DataItems A, B, and C, the following are considered cyclic dependencies (‘=>’ denotes a ‘depends on’):

A => B => A (direct)
A => B => C => A (indirect)

These are detected as part of the calculation process. As cyclic dependencies by their nature cannot be resolved, they are considered calculation errors.

 Naming Conventions

 An Item name uses the following identity pattern similar to an address:

< Company Name > | < Site Name > | < Item Name >
e.g. Company1|Site1|Item1

An Item DataItem name follows the same convention, adding one extra type field to the Item Name address:

< Company Name > | < Site Name > | < Item Name > | < Item DataItem Type >
e.g. Company1|Site1|Item1|CALC

Items also have a numerical identifier called the Item ID and an alias name used to identify the meter during raw data import, but the name is the primary method of identification.

 Meter Properties
Property Description Example
ID Numerical identifier 13891
Name Item name using the address pattern Company1|Site1|Item1
Type The classification of meter defining how aggregation is performed Incrementing
Start Date/End Date The start and end time used in aggregation 01/01/2014
Initial Reading Start value to compare to for aggregation functions that use the last aggregation value 240
Calculated Units A unit description to use in displaying values kWh
Conversion Units The Conversion to be used to convert raw data into calculated data kW to kWh
Costs The Cost to be used for determining unit costs for this Item Electricity
Decimal places The number of decimal places to use in displaying meter values 2
Aggregation Function Function used to aggregate across each aggregation period Average
Aggregation Period Time period between each aggregation point 30 minutes
Item Alias Used asan identifier during raw data import
Calculation Delay The delay, in terms of Aggregation periods, that delay the Item being placed on the calculation queue 3 (0) = Real Time
CalcStartOffset Dictates how far in the past data needs to be loaded. Only needs to be used with Data Point Lists d-1
CalEndOffset Dictates how far in the future data needs to be loaded. Only needs to be used with Data Point Lists and very specific types of calculation where there is a need to calcualte into the future d+2
User Keys 1-3 Optional fields to be used by the user Any string, Ddte or value