Mapping to More Than an Individual Element of an Array

Plant SCADA can only handle simple (same-type) arrays of up to 256 bytes in length, so when declaring variable arrays to access ControlLogix system PLC arrays (or data structures larger than 256 bytes), you will need to split them into smaller structures of less than 256 bytes. For example, you’ll need to declare multiple variable arrays each accessing a separate 256 byte portion of the larger structure.

To map to a portion of an array greater than a single tag, you identify the starting position for the array, and the size of the array to map using the syntax:

<TagName>/<ArrayOffset>!A[<ArraySize>]

Where:

Note:
• The array offset value is a zero-based item count used within the PLC to define the start of the array structure which is being mapped to the Plant SCADA variable tag array being declared. The array size value is a continuation of the same count and is used to define the size of the array structure being mapped to the Plant SCADA variable tag array being declared. They are used together to determine the start and end points of the variable tag array data in the ControlLogix system PLC which will be mapped to for the Plant SCADA variable tag array being declared in the Plant SCADA Variable Tags.
• Plant SCADA ignores all characters following an exclamation mark "!" in the tag address field, so that tag-based drivers like the ABCLX driver can use square brackets in the tag address for device array addressing. Therefore, you must precede an array address schema with an exclamation mark when defining an array in a Plant SCADA variable tag address.

See Also

Mapping to Individual Elements of an Array