Returning multiple records with MaxRowCount

A ProcessValues request with Startbound or Endbound retrieval modes can return multiple records by including the parameter MaxRowCount,

The following GET request specifies a MaxRowCount of 3 and the Startbound retrieval mode:

https://online.wonderware.com/apis/Historian/v2/ProcessValues?$filter=FQN eq 'MountainWaterTreatment.CartridgeFilterOutlet.TemperatureC' and DateTime le 2021-09-03T18:44:09.352247Z&RetrievalMode=Startbound&MaxRowCount=3

As shown in the example below, the above query will return the records for [“00:08”, “10”], [“00:06”, “7”] and [“00:04”, “4”].

The following GET request specifies a MaxRowCount of 2 and the Endbound retrieval mode:

https://online.wonderware.com/apis/Historian/v2/ProcessValues?$filter=FQN eq 'MountainWaterTreatment.CartridgeFilterOutlet.TemperatureC' and DateTime ge 2021-09-03T18:44:09.352247Z&RetrievalMode=Endbound&MaxRowCount=2

As shown in the example below, the above query will return the records for ["00:08", "10"] and ["00:12", "-1"].

Notes on using MaxRowCount with Startbound and Endbound

• In scenarios involving versioned-original records, requests using MaxRowCount will include versioned-original records up to the amount of records specified with the parameter. For example:

  

  In the above data set, specifying a MaxRowCount of 3 and a EndDateTime of 00:07 in a ProcessValues call using Startbound retrieval will return the values recorded at 00:06: 7, 8, and 2.

  If MaxRowCount is set to 2, any two of those three values will be returned.

• In scenarios involving versioned-original and versioned-latest records, requests using MaxRowCount will prioritize versioned-latest records by default. In the following example, using Startbound with a MaxRowCount of 3, the values of 4, 7, and 8 will be returned:

  

  The query can be adjusted to specify that only original records be returned. From the following example query, the values returned will be 9, 7, and 8.