Panasonic FP-E Programming Manual page 1029

Precautions when executing auto−tuning
If "Execute auto−tuning" is specified using the parameter table (control mode [S]), attention should be paid to
the following points.
After auto−tuning has been completed, the control mode [S] area is automatically rewritten from H8000 to
H8003 to H0 to H3. Make sure the mode is not rewritten again in the program.
After auto−tuning has been completed, the optimum values are stored for the proportional gain (Kp), the
integration time (Ti) and derivative time (Td), but before executing auto−tuning, the appropriate values (for
example, the lower limit value) within the setting range must be set.
After auto−tuning has been completed, the optimum values are stored for the proportional gain (Kp), the
integration time (Ti) and derivative time (Td). Be careful that the stored values are not inadvertently rewritten.
Auto−tuning calculates the ideal Kp, Ti and Td values. This is done for setting (SP) by measuring the change
of the measured value (PV) when the output value (MV) is set to the upper limit so that the measured value
(PV) is caused to fluctuate, and measuring the change of the measured value (PV) when the output value
(MV) is set to the lower limit.
The changes of the output value (MV) when auto−tuning will complete after a minimum of three changes:
upper limit output−lower limit output−upper limit output. If the auto−tuning progress remains at 0 even after
changes have occurred several times, please try again after shortening control synchronization Ts.
Precautions during programming
A 30 word area (31 words for the FP0), including the operation work area, is required for the parameter table.
Be careful not to allow other instructions to overwrite values in this area.
Error detection will not occur even if the parameter table exceeds the area.
When specifying "S" specify a number that is within at least 30 words (31 words for the FP0) from the last
number.
Take care that the area is not exceeded due to index modification. An error will not be detected if the area is
exceeded.
Use the A/D converter or other device to input the current measured value S+2.
Use the D/A converter or other device to output the result of PID processing S+3 to the process.
For the FP0, this instruction F355 (PID) cannot be programmed in the interrupt program.
If two or more PID instructions specifying the same table are described in the program, it may operate
incorrectly.
(Example)
X0
F355 PID, DT0
X0
F355 PID, DT0
(Reason)
Because the PID instructions are internally operating using the specified table, even if the execution
condition has not been effected.
In such a case, specify the table in separate addresses.
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High−level Instructions
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