West Control Solutions ProVU 4 - Manual (Page 70)

ProVU4 Controller, Profiler & Recorder/Controller - Product Manual
59407, Issue 1 – March 2008 Profiler Option Page 69
The Auto-Hold Feature
Each profile segment has individual Auto-Hold settings. If utilised, these ensure that the
profile and the actual process remain synchronised. If the process does not closely match
the required setpoint by remaining within the Hold Band, the profile can be held until it
returns within bounds.
The user can choose to hold the profile if the process beyond the Hold Band Above The
Setpoint only, Below The Setpoint only or to Band (either side of the setpoint). When Auto-
Hold is active, the profile status is shown as “Held”.
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 41. Auto-Hold On A Dwell Segment
During a Dwell, the dwell time is increase by the time that the process is outside of the hold
band in the selected direction(s).
Held if Auto-Hold set to Above Setpoint or Band
Process Variable
Ramp Setpoint
(without Auto-
Hold)
Hold Band
Ramp Setpoint
(with Auto-Hold)
Held if Auto-Hold set to Below Setpoint or Band
Figure 42. Auto-Hold On A Ramp Segment
During a Ramp segment, the ramp is held at the current setpoint value while the process is
outside of the hold band in the selected direction(s). The time taken to complete the ramp is
increased by the time taken by the Auto-Hold.