User guide

Data Communication and Host Modes
Rev 3.0D Jul.09 61
idleinter‐charactertime‐outspecifiedinS50(intenthsof
seconds)occursorwhenacharacterisreceivedthatmatches
S51(ifnon‐zero).
UDP Auto Answer
UDPautoanswer(previouslycalledUDPhalf‐open)isset
withS82=2.Whenset,theRavenXTwillautomatically
establishaUDPsessiontothesourceIPaddressandportof
theUDPpacketreceived.TheRavenXTwillremain“locked”
tothisoneremoteIP/portuntilnodataissent
orreceivedfor
thetimeintervaldefinedintheUDPautoanswertime‐out
(S83).Duringthissession,packetsfromotherIP/port
addresseswillberejected,unless*UALLisset.Whetherornot
anincomingpacketwillcausethemodemtoenteraUDP
sessionisalwaysdependentonthe
S53andAIPsettings.
TheNormalUDPMode(MD3)canbecombinedwithUDP
autoanswertocausetheincomingserialdatatobesentin
UDPpackets(insteadofbeingtreatedasATcomm ands),while
allowingsessionstobeestablishedfromdifferentUDP
sources.AUDPsessionwillbeinitiatedeitherbyincoming
serial
dataorbyanincomingUDPpacket.Thesession,started
byeithermethod,willbeterminatedwhennodatahasbeen
sentorreceivedfortheS82period.Oncethesessiontermi
‐
nates,anothermaybeinitiatedbyeithermeans.
Whenidle,afterthetime‐outhasoccurred,themodemisinAT
commandmodeontheserialport,andany validATcommand
maybeenteredduringthistime.
Tip: It is best to ensure the idle time-outs for TCP and UDP are never
0 if you're going to be using auto-answer, or either PAD mode. In
those circumstances, you will want the modem to close the socket if
the connection goes idle for too long, particularly if the other side
doesn’t normally close the connection.
Whenthesessionisinitiatedbyserialdata,thenewsession
willbeestablishedusingthedestinationaddressspecifiedin
S53.TheS53settingcanbe changediftheconnecttolastUDP
setting(*UDPLAST=1)isset.TheaddressinS53willbe
updatedtoreflecttheaddressofthelast
sessioninitiatedbyan
incomingUDPpacket.Sothatwhennewdataisreceivedover
thehostserialportwhileintheidlestate,asessionwillbere‐
establishedwiththelastaddress.(Thisbehavioristhesameas
thepreviousHybrid2(MD6)mode).