
CalAmp
WirelessNetworksTechnicalSupport|Tel507.833.8819|Email[email protected] Page5of10aresentforeachcloseandre‐openoftheTCPconnection.Thisaddsalotofon‐airtrafficandimpactsthesystem
performance.
NotewhenusingdifferentinactivitytimeoutvaluesformessageswiththesameTCPconnection:
WhendifferentmessagesforthesameremotesharethesameTCPconnection,
eachdifferentmessage’sinactivitytimeout
wouldrestartthetimeouttimer.Messageexample:msg1inactivity‐60,msg2inactivity‐100,msg3inactivity‐30.These
messagesarethensentasfollows:msg1issent,msg2issent,msg3andthenawaitisdone.Sincethelastmessagewas
msg3withinactivitytimeout
of30seconds,theTCPconnectionwouldcloseafter30secondsofmsg3.
Settingexampleusingcustominactivitytimeout(100sec).
SummaryonTCPconnectiontimeout(inactivitysetting)
SincethelongestinactivitytimeoutperTCPconnectionwitharemoteunit(PLC/RTU)is120seconds(basedonmessage
inactivitymaxof120seconds),itisimportantthateachremote(PLC/RTU)ispolledwiththe120secondperiodtoavoid
extratrafficresultingfromadditionalTCP/IPopenandcloseconnection
messages.Forsystemswherepollingisdone
infrequently(>120sec)theadditionalTCPtrafficneedstobeconsideredforthesystemtrafficplan.
Fornormaloperationtheinactivitytimeoutdoesnotneedtobespecifiedinthe“Path”setting.Masterandremotesshould
besetthisway,especiallyifremote
PLCssendunsolicitedmessagesorinitiatecommunicationwithotherremotes.Ifa
systemhasamixofPLCs(CompactLogix/ControlLogixwithMicroLogix/SLC),thenalsorefertoCalAmp’s“Allen‐BradleyPLC
forViperSystem”supportbulletinavailableonCalAmp’sWEBsiteundersupport.
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