| 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".
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