Creating Alarms
-
Upload
clyde-cauchi -
Category
Documents
-
view
224 -
download
0
Transcript of Creating Alarms
-
8/10/2019 Creating Alarms
1/15
CHAPTER23 Alarm&EventProgramming
Objectives
Aftercompletingthischapter,youshouldhavetheknowledgeto:
Understand
alarm
programming.
Applythevarioustechniquestocapturealarmandeventinformation.
ManyPLCapplicationsrequiresomeformofalarmingwhenabnormalconditionsoreventsoccur.PLCsare
wellsuitedforthistaskandinfact,manyPLCmanufacturersprovidespecialinstructionsdesignedjustfor
thispurpose. Someofthesespecialinstructionswillbecoveredlaterinthischapter.
Alertingoperatingormaintenancepersonnelofabnormalconditionsorproblemssavestimeandincreases
machineorprocessuptime.Whendetailedalarmingisprovided,manyproblemscanberesolvedby
operatorsthemselvesratherthancallingatechniciantofindtheproblemsavingtimeandincreasing
productivity.
WhenaPLCsystemisconnectedtooneofthemanyHMIinterfacesavailableonthemarkettoday,theHMI
canprovideallofthealarmingfunctionsnecessarywithminimaladditionalPLCprogramming.MostHMI
softwarepackagesprovidesomeformofalarmingandeventrecording. TheseHMIsystemscontinually
monitorthePLCsinternaldatafilesortagsandbasedonhowtheHMIisprogrammedwillalarmaccordingly.
WhenHMIinterfaceswithbuiltinalarmingfeaturesarenotpartoftheoverallsystemorwheneventsmust
becapturedfasterthananHMIsystemcanmonitor,thealarmingandeventrecordingmustbeprogrammed
inthePLC.Thischapterisdedicatedtoshowingthereadersomeofthetechniquesandinstructionsusedto
programalarmandeventinformationinPLCs.
BASIC
ALARM
LOGIC
Alarmsandeventscanbetriggeredfromdigitalinformationsuchasamotorfailingtostartorrun. Theycan
betriggeredfromprocessanalogvaluessuchasahightemperatureorlowpressure. Whethermonitoringa
digitaloranalogvaluetheendresultisthesame,abitortagistypicallysettoa1orONindicatingthata
problemhasbeendetected. Figure231illustratesanexampleofthisbasiclogic.
-
8/10/2019 Creating Alarms
2/15
R
a
a
a
w
m
A
s
t
fr
o
A
r
p
B
b
ung1inFigu
alarmifthe
alogtempe
internalbit
ithanactual
onitored
by
terstudying
itchisturne
ereforethe
actionofas
therPLClogi
similarprobl
ached101
ocess,theo
othproblem
lowinFigur
e231moni
motorisno
atureinput(
ortagthat,
outputthati
an
HMI
inter
Rung1inFi
dON,thest
otoralarm
condmayn
thatusesth
emcanbes
oronlyaspli
eratormay
describeda
e232.
Figu
orsthemot
runningwh
N7:1)andal
henON,ind
lluminatesa
ace
system.
ure231,yo
tusinputfro
willbeONfo
tseemlike
isalarminfo
eninthesec
tsecondcau
notknowwh
ovecanbe
re231Basic
ron/offswit
ntheswitch
rmsifthete
icatesanabn
light,sounds
shouldsee
mthemotor
rafractiono
uchbutitc
mationorfa
ondrungwit
singthehigh
athappened
orrectedwit
AlarmLogic
chandcorre
isintheON
mperaturee
ormalcondi
ahorn,orle
basicprobl
starterdoes
fasecondas
ntriggerfal
lselyturning
htheoverte
temperature
.
hsomesimp
Example
spondingmo
position. Th
ceeds100
ion.Thisint
ftasaninter
mwiththis
notchange
themotorc
ealarmstha
onanalarm
mperaturea
alarmtotur
lechangesto
torstarterst
secondrun
.Inbothrun
rnalbitorta
nalmemory
alarmlogic.
tateimmedi
ontactorcha
tcancausep
output.
larm.Ifthet
nONshuttin
thealarmlo
atusinputto
monitorsa
gstheoutpu
gcanberepl
ddressthat
henthemo
telyand
gesstate.T
roblemswit
mperature
gdownthe
gicasshown
set
tis
aced
is
tor
is
-
8/10/2019 Creating Alarms
3/15
In
al
Te
t
a
a
C
C
ci
m
t
t
thefirstrun
armisactiva
esecond
ru
ampleweh
ealarmset
tion. SeeCh
normalmot
APTURIN
apturingand
rcuitaswas
eaningthea
ealarmrete
ischapter.
ganOnDela
tedwhichis
nguses
asea
veusedthe
ointbefore
apter22for
orcondition
ALARM
retainingala
howninFig
larmstatus
ntiveassho
Figur
yTimer(TO
noughtime
lingcircuit
to
startpushbu
thealarmca
anexample
.
VENTS
rminformati
re232,Run
illbelostift
ninFigure2
e232Enhan
)hasbeena
forthemoto
seal
in
the
a
ttonasther
bereset. T
famotorfa
oncanbedo
g2andsome
heprocessor
33.Otherm
cedBasicAl
dedthatall
rcontactort
larmuntil
th
esetmethod
estartbutt
ltandmonit
neinmultipl
meanstore
losespower
ethods,such
rmLogic
wsforasm
changesta
ealarm
is
re
.Ofcourse,t
ncanberep
oringlogict
eways.Asim
stthealarm.
. Latchingin
asmovingd
lldelaybefo
eandpreve
etby
the
op
hetemperat
lacedwithal
atcanbeus
plemethodi
Thismethod
structionsca
ata,willbed
rethemotor
tafalsealar
rator.In
our
remustbe
mostanyde
dtoalarm
stousease
isnonreten
beusedto
iscussedlate
m.
elow
ired
ling
tive,
make
in
-
8/10/2019 Creating Alarms
4/15
Y
T
p
S
r
m
t
c
a
c
in
c
ti
al
uwillnotice
isisdoneto
shedwhile
NALOGR
meapplicat
pidrateofc
ove,andbit
theevaluati
angingthet
alogvalue(
angeisstor
structionan
rrentanalo
merisdone.
armonade
inFigure23
ensurethat
healarm
is
s
TEOFC
ionsrequire
angeandal
instructions
onperiod(3
imerpreset
8:1)thatwa
dinF8:2an
requiresac
valuewhen
Thislogicmo
reasingrate
Fi
3thattheal
thealarmre
tillactive.
ANGEAL
hatanalogv
rmifsucha
ocreateara
seconds).T
alue.Rung4
sstoredatth
canbechan
orrespondin
thePLCisfir
nitorsforap
ofchangeor
gure233La
rmreset(u
ainssetfor
RMLOGI
luessuchas
conditionexi
teofchange
isevaluatio
comparesth
eendofthe
gedtoanyd
unlatchinst
tstartedso
ositive(incre
bothifdesir
tchingAlarm
latch)rungi
theentirePL
C
temperatur
sts.Thelogic
alarm.Rung
periodcan
ecurrentan
lastevaluati
esiredvalue.
ructiontore
hatafalseal
asing)rateo
d.
Logic
locatedabo
Cprograms
,pressure,l
inFigure23
2inFigure2
besettoany
logvaluest
nperiod.Th
Thealarmo
setthealarm
larmisnotg
fchange,wh
vethealarm
anifthestar
vel,etc.be
4usesatim
4isafreer
desiredvalu
redinF8:0
emaximum
utputislatch
.Rung1isu
neratedthe
ichcanbeea
set(latch)ru
tbuttonis
onitoredfo
r,compare,
unningtimer
ebysimply
iththeprevi
llowablerat
edusingthe
edtostoret
firsttimethe
silychanged
ng.
a
set
ous
eof
latch
he
to
-
8/10/2019 Creating Alarms
5/15
Figur
e234Rate fChangeAl rmLogic
-
8/10/2019 Creating Alarms
6/15
E
b
e
a
yw
d
h
T
t
d
e
T
a
b
NNUNCIA
rlyalarming
ardsuseda
gravedont
nunciators
t
acknowledasacknowle
pendingon
doccurred(
ePLCladde
mperaturea
scribedabo
ampleonh
eovertemp
internalme
ard.
TORLOGI
methodsus
lightbehind
ewindow.
oulduseth
ged
by
the
oged,theala
thestateoft
flashing),wh
logictomi
larmaswas
e. TheFlas
wtoprogra
eraturealar
moryaddres
C
danannunc
anopaquew
hentheala
eemodesto
perator,
the
rmwindow
healarm.Op
icharestilla
ictheearly
howninFig
hercontact
thisflasher
Figur
couldbea
smonitored
iatorboardt
indow.Theo
mwasactiv
indicatean
larm
windoouldstopfla
eratorscoul
tive(illumin
nnunciators
re232and
isasecon
.
235Basic
hardwiredo
byanHMIth
notifyoper
paquewindo
thewindow
larmconditi
would
flashshingandeit
monitorth
ated),andw
isshownFig
ddedthene
On/Offinte
nnunciator
tputtoalig
athasbeen
atorsofprob
wwouldha
wouldbeill
n. Iftheala
indicating
therremainil
annunciato
ichwereno
re235.Her
cessarylogic
rnalmemory
ypeLogic
tonanann
rogrammed
lems.These
ethename
minated. T
rmhadbeen
e
problem.
luminatedo
boardandt
tactive(non
ewehaveus
sothatthe
address.See
nciatorsboa
tomimican
annunciator
fthealarm
esealarm
triggeredbu
nce
the
alarturnoff
ellwhichalar
illuminated).
edthesame
larmfunctio
Chapter22
rdoritcould
annunciator
tnot
m
ms
over
nsas
oran
be
-
8/10/2019 Creating Alarms
7/15
If
B
b
w
y
a
C
In
w
h
w
T
T
s
youonlyha
utifyouhav
comecumb
aytohandle
urecallfro
thebitlevel
hapter6wou
theexampl
ordsofdata.
ndredsofal
ord,file,and
efirststepi
Word
Word
unack
Word
Word
stillac
esecondst
owninFigur
eahandful
morethan
ersomerequ
alargenum
Chapter6
tomakelogi
ldbe
strongl
thatfollows
Laterinthis
armsatone
bitwiseope
stocreatefo
1(N7:0)Raw
2(N7:1)Curr
owledged.
3(N7:2)Ack
4(N7:3)Una
tive.
pistoprogr
e236.
falarmstop
handfulor
iringaddition
erofalarms
DigitalLogic
caldecisions
yrecommen
wewillprog
chapterwe
time. Wewil
atorscanbe
ur(4)intege
Alarmsthi
entAlarms
owledgedAl
cknowledged
ameachofy
Figure2
rogram,the
venafewh
alprogramm
istousebit
atesthatd
.Ifyouaren
edbefore
p
ramthealar
illshowho
lusetheAlle
used.
memorywo
wordconta
containsall
armsconta
Alarmsco
urrawalar
36AlarmSt
themethod
ndredalarm
ingtime,me
iselogicalo
igitallogicn
tfamiliarwi
oceeding.
logicfor16
youcantak
nBradleyPL
rds(16bit)a
instheactua
urrentalarm
insthestatu
tainsthest
bitsusingo
tusLogicUsi
showninFi
stodealwit
moryusage,
gwithword
tationssuch
thdigitallogi
alarms(one
ethisbasica
C5forthise
ndlabelasf
lalarmbitss
sthatareei
sofallackno
tusofallun
neofthe16
ngN7:0Bits
ure235will
,thenthism
andscantim
andfilemov
asAND,OR,
cnotationst
16bitword)
pproachand
xample,but
llows:
etinyourus
heracknowl
wledgedalar
cknowledge
bitsavailable
workjustfin
ethodmay
e.Amuchbe
einstruction
XOR,etc.op
henareview
bymanipula
dealwith
nyPLCwith
rprogram.
dgedor
ms.
alarmsthat
inwordN7:
e.
tter
s. If
erate
of
ting
are
0as
-
8/10/2019 Creating Alarms
8/15
T
w
u
u
T
2
s
ethirdstep
eareusingt
inglogicalo
acknowled
betterund
8a(unackn
ownforeas
istoprogra
oCompute
eratorsint
edalarmwo
Figure
rstandwhat
owledged)a
ofundersta
thelogicto
(CPT)instruc
eexpression
rds.
37Logic
to
eachexpres
dFigure23
nding.
Figure
findallunac
tionstoperf
sofeachco
FindUnackn
ionisdoingi
bforackno
38aUnack
nowledged
rmthistask
puteinstru
owledgedan
nthetwoCP
ledgedalar
owledgedAl
ndacknowl
.Youwillnot
tiontoupda
dAcknowled
Tinstruction
s.Onlythe
armMatrix
dgedalarms
iceinFigure
tetheackno
gedAlarms
srefertothe
firstfivebits
.InFigure23
237thatwe
ledgedand
matrixinFi
ofeachword
7
are
ure
are
-
8/10/2019 Creating Alarms
9/15
In
in
stepfourw
totheackno
programth
wledgedalar
Figure
elogictocle
mwordwhe
Figu
238bAckn
rtheunackn
ntheackno
re239Alar
wledgedAla
owledgedal
ledgedpush
Acknowled
rmMatrix
rmsandmo
buttonispr
geLogic
vethecurre
ssed.SeeFi
talarms(N7
ure239.
:1)
-
8/10/2019 Creating Alarms
10/15
S
R
in
epfiveuses
efertothem
structionof
anotherCPT
atrixinFigur
igure2310.
instructiont
Figur
e2311tobe
updatethe
231016Bi
tterunderst
currentalar
tAlarmLogic
ndthelogic
word(N7:1
Example
loperation
).SeeFigure
eingperfor
2310.
edinthela
tCPT
-
8/10/2019 Creating Alarms
11/15
R
al
st
b
lo
o
T
t
p
m
cpl
u
N
c
c
ungs3,4and
armsuchas
ate.Thisinfo
ards,or
sou
gicisthatit
nescan.
ULTIPLE
increaseth
peinstructio
ograminFig
onitorthest
angingthe
l
antoincrea
acknowled
7:0through
ntainthest
ntainsallac
5inFigure2
hetherthe
rmationcan
ndingahorn
peratesina
LARM&
numberof
nsthatoper
ure2312re
atusof80(1
ngthor
wor
ethenumbe
edandackn
7:4contain
tusofallcur
knowledged
Fig
310monito
alarmhasbe
beusedinm
ifthere
are
singlescana
EVENTCA
alarms(abov
teonmultip
lacestheCP
x5)alarms.
dsto
operate
rinthefutur
wledged)as
therawalar
rentalarms,
alarmsandN
ure2311Cu
all16alarm
enacknowle
anydifferent
nyunackno
ndwilltrapt
PTURING
esixteen)is
lewordsato
T,MOV,and
oucanincre
on.
It
is
reco
ethatyoucr
showninFig
sthatarep
bothacknow
12:0through
rrentAlarms
sandprovid
ged,unackn
wayssucha
ledgedalar
hestatusof
OGIC
simplemat
netimesuch
CLRinstructi
aseordecre
mmendedt
eateasepar
ure2312.
ogrammedi
ledgedandu
N12:4theu
Matrix
theuserwi
owledged,o
sturningon
s.The
real
nyalarmev
erofreplaci
astheAllen
onswithFAL
asethenum
atif
you
hav
tefileforea
ntotheuser
nacknowled
nacknowled
hstatusinfo
rcurrentlyin
arninglight
enefitto
thi
nifthealar
gtheCPTin
BradleyFAL
,COP,andFL
erofalarms
ealarge
nu
chalarmsta
PLClogic.N1
ed.N11:0th
edalarms.
rmationone
anactiveala
sorannunci
type
of
alar
wasonlyo
structionswi
instruction.
Linstruction
bysimply
berof
alar
us(raw,curr
0:0through
roughN11:4
ach
rm
tor
for
thfile
he
sthat
sor
ent,
10:4
-
8/10/2019 Creating Alarms
12/15
Figure2312AlarmLogicExampleForUpTo80Alarms
-
8/10/2019 Creating Alarms
13/15
TheresetoutputinstructionthatfollowseachFALinstructionensuresthattheFALisresetbeforethenext
programscansothatnoalarmsarelost.
Theexamplesshownsofarinthischapterareonlysomeofthemanywaysthatalarminginformationcanbe
handledinthePLC.MostHMIsystemstodayhaveveryextensivealarmingandeventrecordingcapabilities
thatmakeprogrammingalarmlogicinthePLCalmostobsolete.Thequestionsyoumustaskyourselfis,does
theHMIupdatefastenoughtocaptureyouralarmswithoutaddingadditionalPLClogic.
ALLENBRADLEYLOGIX5000ALMD&ALMAINSTRUCTIONS
TheAllenBradleyLogixfamilyofPLCprocessorshastwoalarm/eventinstructionsdesignedspecificallyfor
monitoringdigitalandanalogdataforabnormalconditionsasprogrammedbytheuser. TheseLogixbased
alarminstructionsareavailableforuseinrelayladder,structuredtext,andfunctionblockdiagramprograms.
Theadvantagetousingthesetwoinstructionsisthatwhenanalarmisdetected,thecontrollerwillpublish
theeventtoFactoryTalkViewAlarmsandEventsserversthatpropagatealarmstoFactoryTalkViewSE
clients(HMIs)thatsubscribetoreceivenotifications.
TheDigital
Alarm
(ALMD)
instruction
detects
digital
alarms
based
on
Boolean
(true/false)
conditions.
The
instructionisanoutputinstructionthatobtainsitsalarmconditionfromtherungcondition.Someofthe
featuresoftheALMDinstructionsincludealarmacknowledge,latch,minimumdurationtimer,alarm
counter,timestamp,severity,etc.. Figure2313Rung1showsandexampleoftheALMDinstruction.
TheAnalogAlarm(ALMA)instructiondetectsanalogalarmsbasedonthelevelorrateofchangeofananalog
value.Theinstructionisanoutputinstructionandistypicallyplacedonanunconditionalrung.Someofthe
featuresoftheALMAinstructionsincludealarmacknowledge,highandhigh/highlimits,lowandlow/low
limits,deadband,rateofchange,minimumdurationtimer,alarmcounter,timestamp,severity,etc.. Figure
2313Rung2showsanexampleoftheALMAinstruction.
Becauseof
the
many
features
of
both
of
these
instructions
it
is
not
practical
to
include
acomplete
descriptionhere.Pleaserefertothemanufacturersinstructionmanualforacompletedescription.
-
8/10/2019 Creating Alarms
14/15
C
al
c
p
p
al
u
al
ta
hapterSu
anyPLCapp
armingis
pr
henprogra
ptured,ann
ogrammedi
ogramislar
armsatone
commonto
arms.
ostHMIsyst
eneed
for
P
ddatafiles
mmary
licationsreq
vided,mach
mingalarm
nciated,ack
nconjunctio
ewithman
timewhich
findPLCpro
emstodayh
LCprogram
hatcontain
igure2313
iresomefor
ineor
proces
logic,thepro
nowledged,
withthelo
alarmsitma
illsavetime,
ramsthath
veextensive
edalarm
log
hemachine
llenBradle
mofalarmin
sdown
time
grammersh
ndreset.In
icthatcontr
ybeeasiert
increasePL
vebeencre
alarmingan
ic.These
HM
rprocessin
ALMDand
gwhenabno
canbe
mini
uldtakeint
mallPLCpro
lsthemachi
creatededi
scantime,a
tedwithde
deventcapt
Isystems
ca
ormationsu
LMAInstruc
rmalconditi
izedwhich
i
considerati
gramapplic
ineorproces
catedalarml
nddecrease
icatedprogr
ringfeature
be
program
chaspressur
tions
nsoccur.W
nturn
increa
nhowalarm
tionstheala
s.Ontheoth
logictoproc
memoryusa
amfilesforj
sthatcanre
medto
moni
e,level,runn
enadequat
sesproducti
swillbe
rmlogiccan
erhand,ifth
ssandupda
e.Itisnot
sthandling
uceorelimi
torthe
PLC
t
ing,fault,et
ity.
be
ePLC
eall
ate
ag
.
-
8/10/2019 Creating Alarms
15/15
R
eviewQu
1. What
2. Howd
3.
Write
100F
4.
In
Figu5. Inthe
stions
pairofPLCin
oesthelogic
thealarmlo
.
re
23
12
whPLClogicbel
structionsca
alXORinstru
icthatwillal
t
would
you
w,whenwil
nbeusedto
ctionwork?
armifaproc
change
to
inltheflowala
captureand
esstempera
rease
the
nrmbeactive
retainalarm
ureshouldri
mber
of
alar?
?
seabove25
ms
to
128?
Forfallbelow