A Calculation Tags perform mathematical and logical operations on the values of other tags.
Any tag can be an input to a calculation tag including IO Tags, Block parameters, Constant Tags, Accumulation Tags, and other Calculation Tags.
The calculation function is executed within the software, independent of any control system device. It can be included in trends, displays, alarm summaries and reports.
A calculation Tag is globally accessible but executes locally on the one SCADA node it is configured. It also provides alarming, security, description and other features. A calculation point needs to be configured once on one node and it will be available to all Clients. However, if communication to the SCADA node is lost or the node is taken off line, then the value of the calculation will be lost. All clients, scripts and other tags will see the same value when reading this tag. All other clients, scripts and other tags will see changes to the tag globally.
Calculation Tags have all the alarm and security features of IO Tags.
A calculation tag has a single analog output. It can take up to 20 Inputs that can be Analog or Discrete.
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 detail information see 4.6 Calculation Tags.