Applies To:
  • CitectSCADA 3.xx, 4.xx, 5.xx

You occasionally see cryptic references to "gated values" in Citect Help, KB and manuals. What does the term "gated value" mean? 

A gated value is a term describing a triggered trend tag which currently has the trigger turned off. The term "gate" comes from electronics and transistor logic.

When you define a triggered trend tag, you define a digital variable to control when the trend system acquires values for the trend. When the trigger (the digital tag) is turned on, the information is passed into the trend file currently storing the historical trend data. When the trigger is turned off it effectively "shuts the gate" on the information flow and the trend system ceases to record the value for the trend.

Attempts to display or obtain a trend value at a time when the trigger is (or was) turned off will see Citect return <gated> as the answer; in other words, "at the time you asked for the trend value the trigger was turned off which means the value was blocked and not recorded".