An Accumulation Tag consists of an Integration function from a single tag, usually an IO Tag. The most common use is to totalize the Flow from a flow device (e.g. calculate volume from flow rate). The value of the input tag is "Accumulated" into a total. The totalization function is executed within the software.
Accumulation Tags have a reset value. When the accumulated total reaches this max value, the running total is reset to zero. Accumulation Tags can write to hard drive in order to resume counting without losing all data after power failure or restart of the computer or software.
It also provides alarming, security, description and other features. It can be included in trends, displays, alarm summaries and reports.
Accumulation Tags are a Global Internal Tags: all clients, scripts and other tags will see the same value when reading this tag. Changes to the tag will be seen globally by all other clients, scripts and other tags.
The software license control file limits the number of Internal tags. The number of Internal Tags (Calculation + Accumulation + Constant) cannot exceed the number of IO tags in the license.
For detailed information see 4.5 Accumulation Tags.