Digital Control Tag Type Properties: Feedback Tab
The Feedback tab can be used to select an alarm, alarm priority, digital status, or digital control tag that will provide feedback when this tag's control action has successfully been completed.
Note: Remember, the existence of an output tag is not enough to output a value to the I/O device; you must draw the tag using a control drawing method (such as a Set Value Button) to enable users to send a value to the I/O device and related equipment.
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The Feedback field enables you to specify an existing alarm, alarm priority, digital status, or digital control tag whose value can be used to determine whether the control action for this tag was successful. When a value is output by this tag, the feedback tag reads its value from the I/O device at the same address, and compares this value with the expected value(s) configured in the Feedback At State 0 and Feedback At State 1 spin boxes (see below).
If the Pulse Duration property for this tag (as set on the I/O tab) is set to a valid value greater than 0 (i.e. a pulsed signal), then the Feedback At State 0 property is ignored, as the logic assumes that the control attempt is always to drive the value of the feedback tag to the Feedback At State 1 value.
Note: The 0 state may be inverted to a 1 before writing to the I/O device if this tag's Invert Output property (I/O tab) is set to 1 (true).
If the Pulse Duration property for this tag, as set on the I/O tab, is set to any of: 0 (the default), invalid, or blank (i.e. a non-pulsed signal) then...
The Feedback At State 0 spin box should be set to the value you expect for the selected Feedback tag when this tag has successfully gone to the 0 state. For example, if you've configured this tag to stop a motor by issuing a value of 0 to the I/O device, you would expect the feedback tag (e.g. a digital status tag) to read a 0 back from the I/O device, indicating that your output was received.
If the Pulse Duration property for this tag, as set on the I/O tab, is set to any of: 0 (the default), invalid, or blank (i.e. a non-pulsed signal), then...
The Feedback At State 1 spin box can be used to set the value you expect for the feedback tag when this tag has successfully gone to the 1 state. For example, if you've configured this tag to stop a motor by issuing a value of 1 to the I/O device, you would expect that the feedback tag (e.g. a digital status tag) would read 1 back from the I/O device, indicating that the value was received.
This value can be used as the source for an alarm tag with a time delay to alert the operator that the requested output change has not had the desired effect within a reasonable period of time.