Process Control Instructions
146 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Determining if Target Values Have Been Reached
Once the totalization has been calculated, these rules determine whether the target
or pre-target values have been reached:
• TargetFlag is true when Total Target
• TargetDev1Flag is true when Total (Target - TargetDev1)
• TargetDev2Flag is true when Total (Target - TargetDev2)
Example
In this example, the TOT instruction meters a target quantity of water into a tank
and shuts off the flow once the proper amount of water has been added. When the
AddWater pushbutton is pressed, the TOT instruction resets and starts totalizing
the amount of water flowing into the tank. Once the Target value is reached, the
TOT instruction sets the TargetFlag output, which causes the solenoid valve to
close. For this example, the TOT instruction was "locked" into Program Run by
setting the ProgProgReq and ProgStartReq inputs. This is done for this example
because the operator never needs to directly control the TOT instruction.
Function Block
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