Mitsubishi Electric MELSEC iQ-R Series - Page 1401

11 PROCESS CONTROL INSTRUCTIONS
11.7 Auto Tuning
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11
■Response waveform observation processing
The following processing is performed for the input value (E1).
■Identification processing
The following processing is performed from the maximum ramp value.
Item Processing
Response
waveform
observation
The auto tuning counter is incremented.
The following processing is performed according to the input value (E1) and last measurement value (PV
n-1
).
T2=E1-PV
n-1
• Reserve action (PN = 0)
• Direct action (PN = 1)
The input value (E1) is stored in the last measurement value (PV
n-1
).
Maximum ramp
value
The following processing is performed according to the ramp (T2) and the S.AT1 instruction is terminated.
• Reverse action (PN=0) and AT1
step manipulated value
(AT1STEPMV)  0
• Direct action (PN=1) and AT1 step
manipulated value (AT1STEPMV)
< 0
Maximum ramp
value  Ramp (T2)
• Maximum ramp value = Ramp (T2)
• Maximum ramp counter = Counter from the start of auto tuning
• Maximum ramp PV = Input value (E1)
• Reset the timeout time (after maximum ramp) counter, and start counting
again.
Maximum ramp
value > Ramp (T2)
The last maximum ramp value remains unchanged.
• Direct action (PN=1) and AT1 step
manipulated value (AT1STEPMV)
 0
• Reverse action (PN=0) and AT1
step manipulated value
(AT1STEPMV) < 0
Maximum ramp
value  Ramp (T2)
• Maximum ramp value = Ramp (T2)
• Maximum ramp counter = Counter from the start of auto tuning
• Maximum ramp PV = Input value (E1)
• Reset the timeout time (after maximum ramp) counter, and start counting
again.
Maximum ramp
value < Ramp (T2)
The last maximum ramp value remains unchanged.
Processing Item
Response speed The response speed for calculation (R') and response speed (R) are calculated from the following expressions.
When the response speed (R) is 0, the following processing is performed and the S.AT1 instruction is terminated.
• Identification alarm BB8 is set to 1.
• Auto tuning completion (BB16) is set to 1.
• When the step manipulated value set completion flag is 1, the following processing is performed.
MV=MV-AT1STEPMV
Equivalent dead time The Y-axis intercept (b) when tangent is drawn by the response speed for calculation (R') and the equivalent dead time (L) are
calculated from the following expressions.
b = (PV at maximum ramp) - R'(counter at maximum ramp)AT1ST
When the equivalent dead time (L) is equal to or less than 0, the following processing is performed and the S.AT1 instruction
is terminated.
• Identification alarm BB8 is set to 1.
• Auto tuning completion (BB16) is set to 1.
• When the step manipulated value set completion flag is 1, the following processing is performed.
MV=MV-AT1STEPMV
Maximum ramp value (%)
R'=
AT1ST
, R=
100
|R'|
(/s)
(Auto tuning start-time PV0)-b
R'
L=