West Control Solutions Pro-EC44 - Manual (Page 98)

Pro-EC44 2-Loop Graphical Profile Controller & Recorder
Pro-EC44 Product Manual - 59540-1 October 2013 Page 91
The Auto-Hold Feature
There are independent auto-hold settings for each segment of each loop controlled by the
profile. When utilised, auto-hold ensures that the profile and the actual processes remain
synchronised. If the process does not closely match the setpoints (within the defined Hold
Bands), the profile will be held until it returns within bounds.
When Auto-
Hold becomes active, the profile status is shown as “Held”.
Note: The segment time is increased by the time that the process is out of
bounds, extending the total profile run time.
Auto-hold can be configured to hold the profile if the process goes beyond the hold band
Above The Setpoint only, Below The Setpoint only or it can be set to Band (either side of
the setpoint).
Note: For two-loop profiles, either loop can cause the profile to hold. The entire
profile (i.e. both loops) will be held if either process is outside of its auto-hold
band. It continues only when both loops are back within their auto-hold bands.
Auto Hold Examples
Auto Hold on Dwells
Held if Auto-Hold set to Above Setpoint or Band
Dwell Segment
Setpoint
Hold Band
Process Variable
Held if Auto-Hold set to Below Setpoint or Band
Figure 52. Auto-Hold on a Dwell Segment
During a Dwell, the dwell time is increased by the time that the process is outside of the hold
band in the selected direction(s). This ensures the process was at the desired level for the
required amount of time.