1/17/2022 7:46 AM | |
Joined: 3/19/2015 Last visit: 7/2/2024 Posts: 90 Rating: (28) |
Hi, one reason for such a behavior could be a very high value at the integral sum PIDCtrl.IOutputOld. The integral sum is initialized based on the setting of IntegralResetMode when the PID changes from inactive to automatic mode. Depending on the selected mode, also setpoint and process value have an influence on this initialization. Sometimes problems occur there after power up, when this initialization
You could try what happens when you change the mode from automatic to inactive and then back to automatic again when the PID is in this strange situation. (Alternatively you could switch to manual mode and back to automatic mode, then also the integral sum is initialized to achieve a bumpless switchover.) When the behavior is ok afterwards, then the strange behavior was caused by an unsuitable integral sum value at PIDCtrl.IOutputOld and it might help to check how it came to this value. Another point that could be checked is if your setpoint value also appears at the CurrentSetpoint tag. If not, then it is limited by a configured input or setpoint limit. |
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