Function Block Attributes
494 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Block_02 will still use a value of 25.4 when Block_02 executes this scan. The new
tagA value of 50.9 will not be used by any IREFs in this routine until the start of
the next scan.
In general, the function block instructions that maintain history do not update
history with NAN, or INF values when an overflow occurs. Each
instruction has one of these responses to an overflow condition.
Response Instruction
Response 1
Blocks execute their algorithm and check the result for
NAN or INF. If NAN or INF, the block outputs
NAN or INF.
ALM NTCH
DEDT PMUL
DERV POSP
ESEL RLIM
FGEN RMPS
HPF SCRV
LDL2 SEL
LDLG SNEG
LPF SRTP
MAVE SSUM
MAXC TOT
MINC UPDN
MSTD
MUX
Response 2
Blocks with output limiting execute their algorithm and check the result for
NAN or INF. The output limits are defined by the HighLimit and
LowLimit input parameters. If INF, the block outputs a limited result. If
NAN, the output limits are not used and the block outputs NAN.
HLL, INTG, PI, PIDE, SCL, SOC
Response 3
The overflow condition does not apply. These instructions typically have a
boolean output.
BAND, BNOT, BOR, BXOR, CUTD, D2SD, D3SD,
DFF, JKFF, OSFI, OSRI, RESD, RTOR, SETD,
TOFR, TONR
to Overflow Conditions
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