PID_DUT_31PID_DUT_31This DUT can be used with the following instruction(s):
Control mode
Use this control to select the type of PID processing and auto-tuning activation (X = 8).
16#X000Inverse PI-D control
16#X001Forward PI-D control
16#X002Inverse I-PD control
16#X003Forward I-PD control
I-PD processing is somewhat more flexible than PI-D processing and therefore requires more time for adjustment.
Reverse operation
The manipulated value MV rises when the process value PV sinks (e.g. heating).
Forward operation
The manipulated value MV rises when the process value PV rises (e.g. cooling).
Auto-tuning
Before executing auto-tuning, the appropriate values, e.g. LowerLimit and UpperLimit within the allowed ranges must be set.
When the most significant bit (MSB) in Control is set to 1, auto-tuning is activated. The optimum values for the PID parameters Kp, Ti, and Td are determined by measuring process responses and are stored in Kp, Ti, and Td. Auto-tuning is then deactivated (MSB in Control is set to 0).
Since some operations do not permit auto-tuning, the MSB in Control can be reset to 0 during the auto-tuning process, thereby stopping auto-tuning. In this case, processing is carried out based on the original parameters.
While auto-tuning is active, the manipulated value MV is switched from the upper limit to the lower limit and finally to the upper limit again in the fewest times possible. If the auto-tuning progress does not change from 0 to 1-5 after multiple sessions, shorten the control interval Ts and retry auto-tuning.
The auto-tuning progress is indicated in the parameter AT_Progress from 0 to 5.
Set point value (Range 0–10000)
Here you set the target value that should be reached by the control process. It should fall within the range of the measured value. When using an analog input, you can use a range between 0 and 10000.
Process value (Range 0–10000)
Here you enter the measured process value that you want to be corrected via the operation. An analog-digital converter is necessary for this. Adjust it so that the range of the process value corresponds to that of the set point value.
Manipulated value (Range 0–10000)
The manipulated value (output value) is the result of the PID operation and is stored in this data word.
MV lower limit (Range 0–9999)
Here you enter a lower limit of the manipulated value between 0 and 9999. The value must be smaller than the upper limit.
MV upper limit (Range 1–10000)
Here you enter an upper limit of the manipulated value between 1 and 10000. The value must be larger than the lower limit.
Proportional gain (Range 1–9999, unit 0.1)
In this data word, you write the parameter Kp. The stored value multiplied by 0.1 corresponds to the actual value of Kp. Values in the range of 1 to 9999 (0.1 to 999.9 in 0.1 steps) can be entered. This value is automatically set after auto-tuning has been completed.
Integral time (Range 1–30000, unit 0.1s)
In this data word, you write the parameter Ti. The stored value multiplied by 0.1 corresponds to the actual value of Ti. Values in the range of 1 to 30000 (0.1 to 3000s in 0.1s steps) can be entered. This value is automatically set after auto-tuning has been completed.
Derivative time (Range 0–10000, unit 0.1s)
In this data word, you write the parameter Td. The stored value multiplied by 0.1 corresponds to the actual value of Td. Values in the range of 0 to 10000 (0.1 to 1000s in 0.1s steps) can be entered. This value is automatically set after auto-tuning has been completed.
Sampling time (Range 1–6000, Unit 0.01s)
Here you set the cycle for executing PID processing. The value of the data word multiplied by 0.01 corresponds to the actual value of Ts. Values in the range of 1 to 6000 (0.01s to 60.0s in 0.01s steps) can be entered.
Auto-tuning progress (Range 0–5)
When auto-tuning has been selected for the specified control mode Control, a value from 1 to 5 will be stored indicating the progress of auto tuning.
Working area utilized internally by the PID controller