User guide

Data Communication and Host Modes
Rev 3.0D Jul.09 62
Tip: TCP auto answer (S0) may also be set simultaneously with UDP
auto answer. Then, when in the idle state, the modem will accept
either a TCP or UDP incoming packet, and enter a TCP or UDP
session as appropriate.
Reliable UDP
ReliableUDPaddsasimpleprotocolontopofUDPtoprovide
reliabledeliveryofdata.Whendataisreceivedfromthehost
serialport,a2byteheaderisaddedtothedata,containinga
messagetypeandasequencenumber.TheRavenXTwill
continuetosendthisdata
(bufferinganyreceiveddatainthe
meantime)untilitreceivesanacknowledgementwiththis
sequencenumber.Ifanacknowledgementisnotreceived
withinthetime‐outperiod(specifiedinS7),thedatawillbe
retransmitted.Thiswillcontinueuntilanacknowledgementis
receivedorthemodemisreset.Likewiseany
UDPpackets
receivedbytheRavenXTareexpectedtohavethissimple
header.TheRavenXTwillissueanacknowledgementforany
validpacketswhicharereceived.
ToconfiguretheRavenXTforanormalUDPsession,youneed
tosettheStartupModeDefaultto73(ATMD73).Ifyouare
usingtwomodems,configuretheDestinationIPandPortin
eachtopointtoeachother.Serialdatawillthenbesentreliably
betweenthetwo.
Caution: Although it adds reliability, the simple implementation of the
Reliable UDP mode in the does not check for duplicate packets.
UDP Multicast Mode
UDPMulticastmoderesultsinanydatareceivedfromthehost
serialportbeingsenttoalltheclientsintheaddresslist.The 
remoteportnumberistakenfromS53.Toavoidfloodingthe
network,thepacketsaresenttoeachclientwitha20mspause
inbetween.Thereceipt
ofUDPpacketsworksasinnormal
UDPmode(i.e.boundbythevalueS53and/orAIP).Sinceit
maytakeawhiletotransmitthedatatoallhosts(especiallyif
all20Modbusentriesareusedandnameresolutionsare
required),newdatareceivedfromthehostport
isbuffered
untilcurrenttransmissionstoallhostsarefinished.
EnterthelistoftargetIPsintheaddresslist(ADDRLIST).The
indexnumbersinthelistarenʹtused.Configureforanormal
UDPsession.SettheStartupModeDefaultto83(ATMD83).
ConfiguretheDestinationporttomatchthedeviceportofthe
remotemodems.