Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 229

■SV variation rate & high/low limiter
This function block checks the variation rate and high/low limits to the setting value every control cycle (CT).
• Variation rate limiter
When the control mode is AUT, CAS, or CSV
The SV variation rate high limit value input in percentage is converted into an engineering value, and the processing will be
performed.
DSVL  DSVLT (DSVL: SV variation rate high limit value, DSVLT: SV variation rate high limit value converted into an
engineering value)
Condition
|SV - SVC|  DSVLT
SV -SVC > DSVLT
SV - SVC < -DSVLT
SV: Setting value (target), SVC: Setting value (current)
If DSVLI of the disable alarm detection 2 or ERRI of the disable alarm detection is TRUE, DSVLA will be FALSE.
When the control mode is MAN, CMV, or CASDR
Condition
None
• High/low limiter
When the control mode is MAN, AUT, CAS, CMV, or CSV and SVLMT_EN is TRUE
Condition
Variation rate limiter result > SH
Variation rate limiter result < SL
SL  Variation rate limiter result  SH
If SVLI of the disable alarm detection 2 or ERRI of the disable alarm detection is TRUE, SVLA will be FALSE.
If SVHI of the disable alarm detection 2 or ERRI of the disable alarm detection is TRUE, SVHA will be FALSE.
The high/low limiter result is stored in SVC (setting value (current)).
When the control mode is CASDR, or when SVLMT_EN is FALSE
The variation rate limiter result is stored in SVC (set value (current)).
■Integration stop
This function block stops an integral element operation.
Condition
ISTP = TRUE
ISTP = FALSE
■Derivative stop
This function block stops a derivative element operation.
Condition
DSTP = TRUE
DSTP = FALSE
■Integration stop at MV variation rate limiter occurrence
This function block stops an integral element operation when an MV variation rate limiter alarm occurs.
Condition
When LMT_ISTP is TRUE and a DMLA alarm has
occurred
LMT_ISTP = FALSE
Variation rate limiter result
SV
SVC + DSVLT
SVC - DSVLT
Variation rate limiter result
SV
High/low limiter result
SH
SL
Variation rate limiter result
Processing
The integral element operation is stopped.
Non-processing
Processing
The derivative element operation is stopped.
Non-processing
Processing
When the variation rate of a manipulated value has exceeded a positive/negative limit value and the
sign (positive/negative) of an integral operation value is the same as that of the limit value, the
integral element operation is stopped.
Non-processing
10.8 2-degree-of-freedom Advanced PID Control (Disable Tracking for primary loop) (M+P_2PIDH_)
Alarm 2 (ALM2) target variation rate limit (DSVLA)
FALSE (Reset)
TRUE (Detected)
TRUE (Detected)
Alarm 2 (ALM2) target variation rate limit (DSVLA)
FALSE (Reset)
Alarm 2 (ALM2)
SV low limit (SVLA)
FALSE (Reset)
TRUE (Detected)
FALSE (Reset)
10 LOOP CONTROL OPERATION
SV high limit (SVHA)
TRUE (Detected)
FALSE (Reset)
FALSE (Reset)
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