Mitsubishi Electric MELSEC iQ-R Series, Programming Manual

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11 PROCESS CONTROL INSTRUCTIONS
11.7 Auto Tuning
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Timeout (after maximum ramp) determination processing
This function determines whether the auto tuning processing has reached the AT1 timeout time after maximum ramp
(AT1TOUT2).
However, if the timeout time (after maximum ramp) counter initialization completion flag is 0, "step manipulated value set
processing" is performed.
■
Step manipulated value set processing
This function checks the step manipulated value set completion flag to determine whether the step manipulated value has
been set (1) or not set (0).
• When the step manipulated value set completion flag is 0, the following processing is performed.
The AT1 step manipulated value (AT1SETPMV) is added to the manipulated value (MV).
T1=MV+AT1STEPMV
The upper/lower limiter function performs the following operations, and outputs the result to the output upper limit alarm (BB4)
and output lower limit alarm (BB5).
• When the step manipulated value set completion flag is 1, "sampling cycle determination processing" is performed.
■
Sampling cycle determination processing
This function checks the AT1 sampling period (AT1ST) to determine whether the sampling period has been reached.
• If the sampling period has not been reached, the S.AT1 instruction is terminated.
• If the sampling period has been reached, "response waveform observation processing" is performed.
Auto tuning processing Processing details
If the AT1 timeout time after maximum ramp (AT1TOUT2) is
reached "Identification processing" is performed.
If the AT1 timeout time after maximum ramp (AT1TOUT2) has
not been reached "Step manipulated value set processing" is performed.
Condition Result
BB4 BB5 BB16 MV Processing after upper/lower limiter
T1 > MH 1 0 1 Original MV
remains
unchanged. The S.AT1 instruction is terminated.
T1 < ML 0 1 1
ML

T1

MH 0 0 0 T1 The following processing is performed.
• The step manipulated value set completion flag is set to 1.
• The auto tuning counter is set to 0.
• The input value (E1) is stored in auto tuning start PV0.
• The input value (E1) is stored in the last measurement value (PV
n-1
).
• The maximum slope value, maximum ramp counter, maximum ramp PV, response
speed (R), and equivalent dead time (L) are set to 0.