enabled or disabled. Holdback has three parameters: -holdback wait
time, -holdback band and -holdback type. If the error from the
set point exceeds the set holdback band (HBBD), then the holdback
feature, if enabled, will automatically freeze the profile at its current point
and flash the HLD light. At the same time, the holdback timer begins to
count. When the value of holdback timer exceeds the value of holdback
wait time HBT, the profiler will no longer be freezed and jump to its next
segment, at the same time an error code will be displayed. When
the error comes within the holdback band (HBBD), the program will resume
normal running. There are four different Holdback types. The choice of type
is made by setting HBTY parameter when creating a profile, and may be
one of the following:
HBT
HBBD HBTY
HBT
HBBD HBTY
- Disables Holdback - no action is taken.
- Deviation Low Holdback holds the profile back when the process
value deviates below the set point by more then the holdback
band (HBBD).
- Deviation high holdback holds the profile back when the process
value deviates above the set point by more than the holdback
band (HBBD).
- Deviation Band Holdback is a combination of the two. It holds the
profile back when the process value deviates either above or below
the set point by more than the holdback band ( HBBD ).
HBT is a global parameter which is common to all profiles. HBBD
is a parameter which apply to a specific profile. HBTY is a
parameter which apply to a segment in a specific profile.
UM0P411B
69
4-7 Holdback4-7 Holdback
As the set point ramps up or down (or dwells), the measured value may
lag behind or deviate from the set point by an undesirable amont.
"Holdback" is available to freeze the profile at its current state, should this
occur. The action of Holdback is the same as a deviation alarm. It can be
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