User`s manual

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MELSEC-Q
9 CONTROL OPERATION INSTRUCTIONS
(7) Change rate, upper/lower limiter
Change rate and upper/lower limit checks are performed on a difference between the
temporary MV (T) and manipulated value (MV), and the data and alarm are output after the
limiter processings.
(a) The change rate limiter performs the following operation and outputs the result of the
operation to BB5 and DMLA.
Condition BB5, DMLA T1
|
T
MV
|
DML 0 T
(T
MV)
DML 1
*1
MV DML
(T
MV) DML 1
*1
MV DML
*1: When DMLI or ERRI in the alarm detection inhibition (INH) is set to 1, DMLA and BB5 show 0
since the alarm is prohibited.
(b) The upper/lower limiter performs the following operation and outputs the result of the
operation to BB3, BB4, MHA and MLA.
Condition BB4, MLA BB3, MHA MV
T1 MH 0 1
*2
MH
T1 ML 1
*3
0ML
ML T1 MH 0 0 T1
*2: When MHI or ERRI in the alarm detection inhibition (INH) is set to 1, MHA and BB3 show 0 since
the alarm is prohibited.
*3: When MLI or ERRI in the alarm detection inhibition (INH) is set to 1, MLA and BB4 show 0 since
the alarm is prohibited.
(8) Output conversion
In the output conversion, the output value is calculated from the following formula.
100
NMAX NMIN
BW
MV
NMIN
(9) Loop stop processing
(a) Setting 1 in SPA of the alarm detection (ALM) selects a loop stop.
A loop stop performs the following processing and terminates the S.PIDP instruction.
1) BW retains the last value.
2) DVLA, MHA, MLA and DMLA of the alarm detection (ALM) are turned to 0.
3) The operation mode (MODE) is changed to MAN.
4) BB1 to BB5 of BB are turned to 0.
(b) Setting 0 in SPA of the alarm detection (ALM) selects a loop run.
A loop run performs "(10) Control cycle judgment".
(10) Control cycle judgment
(a) When the specified control cycle is not reached, BW is retained and the S.PIDP instruction
is terminated.
(b) When the specified control cycle is reached, "(1) SV setting processing" is performed.