Trigger Types

Assign a trigger, or collection type, to your calculation tag in the same manner as any other tag. The trigger can be scheduled (polled) or unsolicited (event-based). When you set an event-based trigger, you must also set up a dependency list of one or more tags.

Polled type

Use when you want to schedule the exact time or interval for a calculation to trigger.

Polled collection example:

If you want to collect summary (or rollup) information, such as an hourly average of data at a scheduled interval, you would use polled calculations.

Unsolicited type

Use when you want calculations to be performed on an event-basis. Event-based calculations will keep calculations as up to date as possible. They are also useful when you want to do on-demand calculations. You can use a trigger tag that is written to by an external program or operation.

Unsolicited collection example:

If you want to perform raw sample replication you would use the unsolicited collection type. To retrieve data from tag, instead of two, use the formula:

Result=CurrentValue("Tag1")+CurrentValue("Tag2")

If you are using recovery mode, all referenced tags in an unsolicited calculation must be listed as trigger tags, because recovery will be performed only for the configured trigger tags.