An Viper Cclogix
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Transcript of An Viper Cclogix
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ALLENBRADLEYCONTROLLOGIXAND
COMPACTLOGIXPLCAPPNOTEFORVIPER
SYSTEM
PN0095008325
Revision0
ReleasedNovember2011
TECHNICALSERVICESUPPORTBULLETIN
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CONTENTS
1. Overview.........................................................................................................................................................................3
2. AllenBradleyCompactLogix/ControlLogixPLCs.............................................................................................................3
2.1.
PLCladder
logic
on
restart
opens
all
connections
at
once
instead
of
sequentially
...................................................
3
2.2. ABCompactLogix/ControllogixseriesPLCsEtherNet/IPconnectiontimeout...........................................................4
2.3. ABCompactLogix/ControllogixseriesPLCssendstomanyCIPForwardOpenandCIPForwardClose..............6
2.4. ABCompactLogix/ControlLogixseriesPLCssendsmanyTCP/IPkeepalivemessages...............................................9
3. Viper.............................................................................................................................................................................10
3.1. SetupViperinroutermode(insteadofBridgemode).............................................................................................10
3.2. FilteringTCPkeepalivewithViperTCPproxymode................................................................................................10
3.3. ReplacingorresettingaViperusingproxymodewithoutrestartingpolling...........................................................10
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1. OVERVIEW
AguidetoassistwithAllenBradleyCompactLogix/ControlLogixcommunicationsetupbetweenmasterPLCandremotePLC
usingABEtherNet/IPTCPprotocolbetweenPLCs.
PLCcommunication
via
serial
lines
or
serial
terminal
server
is
not
covered
here,
never
the
less
some
of
the
information
couldapply.
NOTE:PleaseconsulttheCalAmpsViperGeneralPLCsetupsupportbulletinforimportantinformationonsettingup
systemswithPLCs.
2. ALLENBRADLEYCOMPACTLOGIX/CONTROLLOGIX PLCS
BelowisalistofimportantsettingstoimprovecommunicationwhenusedwithalimitedbandwidthVipernetwork.More
informationoncommunicationcanbefoundintheCalAmpsViperGeneralPLCsetupsupportbulletinonCalAmps
supportWebpage.
NOTE:Whenrequired,contactyourPLCproviderorAllenBradley/RockwellAutomationsupport.
2.1. PLC LADDER LOGICON RESTART OPENS ALL CONNECTIONS ATONCEINSTEAD OF
SEQUENTIALLY
WhenPLCladderprogramissetuptohaveatstartupallwritemessagerungssettotrue,allTCPconnectionsaretriggered
"simultaneously".ThiscreatesanoverloadofTCPSYNsandsomewhatcouldcongesttheonairtrafficdependingonthe
system.
Itisrecommendedtosetuptheladderwritemessagerungsnottostartupsimultaneously.Writemessagesshouldbesetup
toopentheTCPconnectionsequentially.FormoreinformationcontactyourPLCproviderorAllenBradley/Rockwell
Automationsupport.
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2.2. AB COMPACTLOGIX/CONTROLLOGIX SERIES PLCSETHERNET/IP CONNECTION TIMEOUT
(SETTING TIMEOUT TO SHORTCANCAUSEPROBLEMS!)
WhenusingtheEthernet/IPwithAllenBradleyCompactLogix/ControlLogix(Logixseries),theTCPConnectiontimeoutisset
onapermessageinstructionbasisusingMessageConfigurationratherthanChannelconfiguration Channel1ofthe
MicroLogixseries.
WhenmessagesaredefinedusingMessageConfigurationandusingpathex:LocalENB,2,192.168.1.9:1,0.
Briefdescription:
TCPconnectionisopenedwhenthefirstmessageissent.
TheTCPconnectiontimeoutissetbydefaultto120secsincetheinactivitydefaultsettingis120sec.
WhileconnectionisestablishedwithsameremoteIPandsameport,ex:192.168.1.9, othermessageswilluse
thesameTCPconnection,andthereforeresettingthetimeoutcountforeachmessagesent.
Whenallmessagesareusingthesamedefaultinactivitytime(120sec)theTCPconnectionsstaysopenaslong
thenextmessageissentwithintheinactivitytimeoutperiod.
TheTCPconnectionisclosedafterthelastmessageplustheinactivityperiod(default120sec).
The
TCP
connection
can
also
be
terminated
based
on
network
connection
problems.
Exampleusingdefaultinactivitytimeout(120sec).
OverwritingthedefaultinactivitytimeoutfortheTCPconnectioninMessageConfiguration:
(Notrecommendedunlessrequired)
ItispossibletooverwritetheMessageConfigurationdefaultinactivitytimeoutvaluebyusingpathex:LocalENB,2,
192.168.1.9:inactivity100,1,0.Usinginactivity100wouldsettheinactivitytimeoutto100secondsinsteadofthedefault
120seconds.(Note:Settingofinactivityx:wherexcanbebetween1and120seconds,usingx>120secondswilldisable
themessagecompletely).
Overwritingthedefaultinactivitytimeoutisnormallynotrequiredandcancauseadditionalsideeffects.Oneoftheseside
effectswouldbewhentheinactivitytimeoutislessthanthelongestdelaybetweentwomessages;additionalIPmessages
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aresentforeachcloseandreopenoftheTCPconnection.Thisaddsalotofonairtrafficandimpactsthesystem
performance.
NotewhenusingdifferentinactivitytimeoutvaluesformessageswiththesameTCPconnection:
WhendifferentmessagesforthesameremotesharethesameTCPconnection,eachdifferentmessagesinactivitytimeout
wouldrestartthetimeouttimer.Messageexample:msg1inactivity60,msg2inactivity100,msg3inactivity30.These
messagesare
then
sent
as
follows:
msg1
is
sent,
msg2
is
sent,
msg3
and
then
await
is
done.
Since
the
last
message
was
msg3withinactivitytimeoutof30seconds,theTCPconnectionwouldcloseafter30secondsofmsg3.
Settingexampleusingcustominactivitytimeout(100sec).
Summary
on
TCP
connection
timeout
(inactivity
setting)
SincethelongestinactivitytimeoutperTCPconnectionwitharemoteunit(PLC/RTU)is120seconds(basedonmessage
inactivitymaxof120seconds), itisimportantthateachremote(PLC/RTU)ispolledwiththe120secondperiodtoavoid
extratrafficresultingfromadditionalTCP/IPopenandcloseconnectionmessages.Forsystemswherepollingisdone
infrequently(>120sec)theadditionalTCPtrafficneedstobeconsideredforthesystemtrafficplan.
FornormaloperationtheinactivitytimeoutdoesnotneedtobespecifiedinthePathsetting.Masterandremotesshould
besetthisway,especiallyifremotePLCssendunsolicitedmessagesorinitiatecommunicationwithotherremotes.Ifa
systemhasamixofPLCs(CompactLogix/ControlLogixwithMicroLogix/SLC),thenalsorefertoCalAmpsAllenBradleyPLC
forViperSystemsupportbulletinavailableonCalAmpsWEBsiteundersupport.
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2.3. AB COMPACTLOGIX/CONTROLLOGIX SERIES PLCSSENDS TO MANYCIPFORWARDOPEN
AN D CIPFORWARDCLOSE
WhenusingtheEtherNet/IPwithCIPcommunicationprotocolwithAllenBradleyCompactLogix/ControlLogixPLCs(and
withotherLogixseriesPLCs),theoptiontouseConnectedorUnconnectedisavailableintheMessageConfiguration.
BydefaulttheConnectedcheckboxisselectedandthereforeitwilladdadditionalmessages(CIPforwardopenandCIP
forward
close
messages)
for
each
read
/
write
operation
when
next
message
is
sent
outside
the
message
timeout
period
(default=30sec).
Tolowertheonairtrafficthe"Connected"checkboxshouldbeunchecked(Unconnected).
ConnectedorUnconnectedoperationdescriptionforCIP:
Whenthe"Connected"checkboxischecked(Connected),ifthere'snotaCIPconnectionalreadyestablished,then
thecontrollersendsanopenforwardCIPconnectioncommandandwaitsforthegoodresponsepriorto
transmittingthereadorwritecommand. TheCIPconnectionremainsopenaslongasthereisactivitypriortothe
timeout(default=30sec). AnymessageinstructionsendingcommandstothesamedevicecanusethesameCIP
andTCPconnection. Ifthistimeoutisreached,acloseCIPconnectioncommandissent.
Whenthe"Connected"checkboxisunchecked(Unconnected),thecontrollerusestheUnconnectedCIPserviceto
transmitthereadorwritecommand,sothereislessoverhead.
TheConnectiontimeoutisonapermessageinstructionbasisasshownbelow thisiswithregardstotheCIP
ConnectiononlynottheTCPconnection,whichisonlycontrolledbytheInactivityTimeout:
For the Logix controllers, theUnconnectedTimeout has to be individually adjusted in each message
instruction tag. The default is 30,000,000 microseconds (30 seconds):
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Whenusing
Message
type
EtherNet/IP
CIP
protocol.
TolowertheonairtrafficuncheckConnectedintheMessageConfigurationmethod.
BelowisanexamplewhentheMessageTypeis"CIPDataTableRead"or"CIPDataTableWrite". Notethatthe
"Connected"checkboxshouldbeunchecked,thisis becauseifyouleaveitchecked,theneverytimetheMSGinstructionis
executedaCIPconnection(withCIPopenmessage)willbeestablishedandbroken(withCIPclosemessage) whichadds
unnecessarilytothenetworktraffic.
Whencommunication
between
ControlLogix/CompactLogix
and
other
Logix
series
PLCs.
ThesePLCs/ControllerusuallyuseEtherNet/IPCIPunconnectedprotocoltocommunicatebetweeneachother.
Note(seebelow)thatwhentheMessageTypeis"SLCTypedRead"or"SLCTypedWrite",theLogixMSGinstructionalways
usesanUnconnectedCIP(noticethatthe"Connected"checkboxisuncheckedandgrayedout).Forexamplethisisused
whenusingPCCCencapsulatedinEtherNet/IPcommand.OthersthanreadorwriteforSLCtypesarenotdescribedinthis
document.
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SummaryofConnectedorUnconnectedoperation
WithConnectedoptionselectedandpollingintervalbetweenMessagesforthesameremoteCIPconnectionislonger
thantheUnconnectedTimeout(default30seconds),CIPForwardOpenandCIPForwardClosemessagesadd4extra
onairmessages(includesmsgreply)foreachunitpolled.Ifeachpollis2messages(msgandreply)the4extramessages
increasethemessageload(onair)by200%.
Therefore"Connected"checkboxshouldbeunchecked(Unconnected)toavoidsending)CIPForwardOpenandCIP
ForwardClosemessages.IfConnectedisrequiredthenincreasetheUnconnectedTimeoutandConnectionRate
timeoutto
avalue
greater
than
the
polling
interval
per
remote
(use
precaution
with
this).
TimeoutsusedformessageresponsesoverEtherNet/IPConnectedorUnconnectedshouldnotbetooshort,therefore
shouldnotbesetlowerthan15sec(normally)intheeventitisrequiredbeinglowerthan30sec forapplicationlevel
retransmission.TheTCP/IPcommunicationdriverdoesitsownretransmissionsandwillnotrequireapplication
retransmissionsofmessagessinceaTCPconnectionwillnotlooseamessageunlesstheconnectionterminatesnormallyor
duetoaproblem. ThereforewithTCPlongertimeoutswithinreasonareok.Longertimeouts(ex30sec)areoksincethey
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minimizeduplicatedmessagebeingbufferedbyTCPintheeventofnetworkcongestionorcommunicationproblemswith
remoteunit.
WithfuturereleasesofPLCsoftware/firmwarethedescribedoperationcouldchange.Itisalwaysrecommendedtobe
informedonPLCreleasechangesfromyourPLCproviderorAllenBradley/RockwellAutomationsupport.
2.4. AB COMPACTLOGIX/CONTROLLOGIX SERIES PLCSSENDS MANYTCP/IPKEEPALIVE
MESSAGES
TheCompactLogix/ControlLogixseriesPLCssendsTCP/IPkeepalivemessagesevery8secondsinbothdirectionsforeach
TCPconnection.WhenseveralPLCsdothesameitispossiblethatagoodpartoftheonairbandwidthisusedupbythe
keepalivetraffic.
WerecommendthattheViperisconfiguredinroutermodeandthatTCPproxyisenabled.TheViperTCPproxyfeaturewill
filterouttheTCP/IPkeepalivemessages.
ThePLCsTCPkeepalivecannotbedisablednoradjusted.RecommendedtoAllenBradley/RockwellAutomationtohavean
optioninthePLCsettingstodisablekeepaliveandhavingusersettablekeepaliveintervals.Thiscouldpotentiallybecome
availableinfuturereleasesofPLCfirmware.
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3. VIPER
3.1. SETUP VIPERINROUTER MODE (INSTEAD OF BRIDGEMODE)
Info:ViperBridgemodecannotfilterkeepaliveandcannotoperateinTCPproxymode.
IfthesystemhasveryfewunitsandfewmessagesViperBridgemodecouldbeused.ButforlargersystemsandPLCdoing
manykeepalives,oronairnetworkbeingcontentious,itmayberequiredtouseroutermode.Routermodeallows
retransmissionofmessageslostduetoonaircontention.Bridgemodeonlydoesbroadcastswithoutretries.InBridge
modetheapplicationneedstoretrylostmessages.
3.2. FILTERINGTC P KEEPALIVE WITHVIPERTCP PROXYMODE
WhenusingTCPprotocolandhavingPLCswheretheTCPkeepaliveratecannotbecontrolled,itisimportanttoenable
ViperTCP(OIPproxy)mode.ThisrequiresthatallVipersareconfiguredinroutermode(ViperBridgemodecannotfilter
keepaliveandcannotoperateinTCPproxymode).
Note:ForPLCswherethekeepalivecanbecontrolledandarerequired,setkeepaliveto4minutes.
OneoftheViper'sTCPproxymodeusagesallowsfilteringofkeepalivemessagesandpreventsthemtobesentovertheair.
Withoutthisfiltering,severalPLCssendingkeepalivemessagescouldeasilyloadtheonairnetwork.
SeeViperusermanualandWebpagestoenableproxy.BydefaultViperproxymodeisenabled.SeeViperWebpage
Advancedsetup >OIPoptimizations.AlsounderNetworkmanagement >NeighborTables(neighbormanagement)make
surethatneighborsareconfiguredwiththeproxyattribute.
3.3. REPLACINGOR RESETTING A VIPERUSINGPROXYMODEWITHOUT RESTARTING POLLING
Whenreplacingorresetting:aremoteViper,aViperusedasarepeater,orevenamasterViperconnectedthrougha
switch,theViperproxycontextislostandwilloperatewithouttheproxybenefit.
ToreestablishTCPproxycontextfortheTCPconnection,thePLCneedstoclosetheoldTCPconnectionandreopenanew
TCPconnection.ThereforenormallyafterdoingVipermaintenancethemasterPLCneedstoberestarted.FutureViper
firmwaremayreestablishproxyautomatically.