Primary Loop Control

Primary Loop Control

Primary loop control is typically used by a primary PID loop to obtain bumpless switching and anti-reset windup when using Cascade/Ratio mode. The primary loop control includes the initialize primary loop output and the anti-reset windup outputs. The InitPrimary output is typically used by the CVInitReq input of a primary PID loop. The windup outputs are typically used by the windup inputs of a primary loop to limit the windup of its CV output.
primary loop control for process
Item
Description
1
InitPrimary is cleared
2
WindupHOut is cleared
(4)
3
WindupLOut is cleared
(4)
4
InitPrimary is set
(1)
5
WindupHOut is set
6
WindupLOut is set
7
CVInitializing is set or not Cascade/Ratio mode
(2)
8
CVInitializing is cleared and Cascade/Ration mode
(3)
9
SHPAlarm is set or appropriate Cv alarm
(5)
10
SHPAlarm is cleared and no CV alarm
(6)
11
SPAlarm is set or appropriate CV alarm
(7)
12
SPAlarm is cleared and no CV alarm
(8)
  1. During first scan, the instruction sets InitPrimary.
  2. When CVInitializing is set or when not in Cascade/Ratio mode, the instruction sets InitPrimary.
  3. When CVInitializing is cleared and in Cascasde/Ratio mode, the instruction clears InitPrimary.
  4. During instruction first scan, the instruction clears the windup outputs. The instruction also clears the windup outputs and disables the CV windup algorithm when CVInitializing is set or if either CVFaulted or CVEUSpanlnv is set.
  5. The instruction sets WindupHOut when SPHalarm is set, or when ControlAction is cleared and CVHAlarm is set, or when ControlAction is set and CVLAarm is set.
    The SP and CV limits operate independently. A SP high limit does not prevent CV from increasing in value. Likewise, a CV high or low limit does not prevent SP from increasing in value.
  6. The instruction clears WindupHOut when SPHalarm is cleared, and not (ControlAction is cleared and CVHAlarm is set), and not (ControlAction is set and CVLAlarm is set).
  7. The instruction sets WinindupLOut when SPLAlarm is set, or when ControlAction is cleared and CVLAlarm is set or when ControlAction is set and CVHAlarm is set.
    The SP and CV limits operate independently. A SP low limit does not prevent CV from increasing in value likewise a CV low or high limit does not prevent SP from increasing in value.
  8. The instruction clears WindupLOut when SPLAlarm is cleared and not (ControlAction is cleared and CVLAlarm is set) and not (ControlAction is set and CVHAlarm is set).
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