Mitsubishi Electric MELSEC iQ-R Series, Programming Manual

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11 PROCESS CONTROL INSTRUCTIONS
11.3 Control Operation Instructions
■
Tracking processing (1)
• Tracking processing is performed when all of the following conditions are satisfied.
• If the set value (E2) is the upper loop MV, the TRKF of the disable alarm detection (INH) of the upper loop is set to 1.
■ Variation rate limiter (2)
Variation rate limiter processing performs the following operations, and stores the result in the current ratio value (R
n
).
■ Ratio calculation (3)
The ratio calculation is performed with the following operational expression.
■ Loop stop processing (4)
The following processing is performed according to the SPA status of the alarm detection (ALM).
■
Control cycle determination (5)
If the specified control cycle is not reached, output value (BW) is set to 0 and the S.R instruction is terminated.
If the specified control cycle is reached, "mode determination (6)" is performed.
■ Mode determination (6)
The following processing is performed depending on the control mode (MODE).
Operation error
• The tracking bit (TRK) is set to 1.
• The set value (E2) is used.
• The control mode (MODE) is set to any of the following: MAN, AUT, CMV, CMB, CAB, LCM, LCA, or LCC.
Condition Operational expression
(SPR-R
n
)

DR R
n
=R
n-1
+DR
(SPR-R
n
)

-DR R
n
=R
n-1
-DR
|SPR-R
n
|<DR R
n
=SPR
SPA status Processing details
1 The loop stops. When the loop stops, the following operations are performed and the S.R instruction ends.
• The last output value (BW) is held.
• The control mode (MODE) is set to MAN.
0 The loop runs and "control cycle determination processing (5)" is performed.
Control mode (MODE) Processing details
CAS, CCB, CSV • If the set value (E2) is specified, engineering value transformation processing (refer to the following
expression) is performed, and then "variation rate limiter (2)" is performed.
• If the set value (E2) is not specified, "variation rate limiter (2)" is performed without performing
engineering value transformation processing.
MAN, AUT, CMV, CMB, CAB, LCM, LCA, LCC "Tracking processing (1)" is performed.
Error code
(SD0) Description
3400H An invalid operation (such as division by zero) is performed.
3402H The value specified by (s1) or (d2) is a subnormal number or NaN (not a number).
3403H An overflow has occurred.
3405H The control cycle (CT) setting is less than 0.
The execution cycle (

T) setting is less than 0.
The value divided the control cycle (CT) by the execution cycle (

T) exceeds 32767.
100
E2=
RMAX-RMIN
×(SPR-RMIN)
BW= ×E1+BIAS
RMAX-RMIN
R
n
-RMIN
SPR= ×E2+RMIN
100
RMAX-RMIN