Temporary (ad hoc) displays with calculations

You can include a calculation in a URL for a temporary (ad hoc) display. To include a Calculation data item, the calculation must be referenced in the DataItems parameter and also defined in the calculations parameter. The calculations parameter must contain a valid JSON string with either one calculation definition, or multiple calculation definitions in an array. Each calculation definition must define a Name, Server, and Expression at minimum. For additional available calculation properties, see Calculation parameter reference.

The DataItems parameter must refer to a calculation by name and choose a column. The format for a calculation data item is: calc:<CalculationName>.<Column>. For example:

?DataItems=calc:Temperature.Value;calc:Level.Maximum

The final URL must include both the data items and the calculation definitions. For example:

?DataItems=calc:Temperature.Value;calc:Level.Maximum&Calculations=[{"Name":"Temperature","Server":"piserver","Expression":"'CDT158' - 100"},{"Name":"Level","Server":"piserver","Expression":"'BA:Level.1' - 25"}]

Examples

• Single calculation definition

  {"Name":"Temperature","Server":"piserver","Expression":"'CDT158' - 100"}

• Multiple calculation definitions

  [{"Name":"Temperature","Server":"piserver","Expression":"'CDT158' - 100"},
  {"Name":"Level","Server":"piserver","Expression":"'BA:Level.1' - 25"}]