The ReadRange service reads a range of data from a List-type property. The execution of this service is implemented using two Tags. The ReadRangeCommand Tag is used to trigger this service and the ReadRangeResult Tag receives the result of this operation.

Both Tags use a Configuration by Strings to reference a specific device, object, and property. The referenced property must have a List type. At the end of the Item parameter, separated by a space, a text must be included identifying the Tag, as in the next example.

•ParamDevice: "15:"

•ParamItem: "trendLog-10.logBuffer ReadRangeCommand"

The ReadRangeCommand must be a write-only Tag. To start this service, this Tag must receive the writing of an array with 3 (three) Elements, in the following format:

•Element 0: Type, a text value identifying the type of range to read. Valid values are FullRange, Position, SequenceNumber, or Time

•Element 1: Reference, a reference to the initial or final Element. If the type of range is equal to Position or SequenceNumber, this must be and unsigned integer. If the type of range is equal to Time, this must be a date and time

•Element 2: Count, an integer value informing the number of Elements to read. For positive values, the reference is the beginning of the range. For negative values, the reference is the end of the range

The ReadRangeResult Tag must be configured as a read-only Block Tag with 6 (six) Elements. The Elements and their data types are the following:

•Element 0: First Item, a Boolean value

•Element 1: Last Item, a Boolean value

•Element 2: More Items, a Boolean value

•Element 3: Item Count, an unsigned integer value

•Element 4: Item Data, a text value in XML format

•Element 5: First Sequence Number, an unsigned integer value, available only in SequenceNumber- and Time-type ranges