BRONKHORST FlowDDE - DDE COMMUNICATION BY CLIENTS; BASIC PARAMETER COMMUNICATION; SPECIAL OPTIONS

BRONKHORST®
Page16FlowDDE     9.17.067
5 DDECOMMUNICATIONBYCLIENTS
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5.1 BASICPARAMETERCOMMUNICATION
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ClientapplicationscommunicatetotheFlowDDEserverbyusingDDEmessages.Beforemessagescanbeexchanged,a
DDE link had to be made. A DDE link consists of three parts: the server, the topic and an item. For separation the
characters'|'and'!'maybeused,soaDDE
linkine.g.MicrosoftExcelbecomesServer|Topic!Item.
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ForstandardinstrumentparametersandtheFlowDDEserver,theseare:
 Server: FlowDDEorFlowDDE2
 Topic: C(X) forchannelX
 Item: P(Y) forparameterY
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AnexampleofaDDElinkinaMicrosoftExcelcellis=FlowDDE|’C(1)’!’P(8)’toread
parameter8ofchannel1.
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5.2 SPECIALOPTIONS
5.2.1 Channel0
Specialcommands canbesenttoFlowDDEbymeansofthecommandchannel0,C(0).Thischannelisnotrelatedto
anyFLOW‐BUSinstrument,butisforFlowDDEcontrolonly.Channel0containsP(0),P(1)andP(2)itemsonly.
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P(0)isthecommandparameter.Writeanumberto
P(0)willtriggerFlowDDEtoreadallparametervaluesfromoneor
morechannelsandupdatetheparametervaluesattheDDElevel.Toreadasmalleramountofparameters,parameter
groupscanberead.Whichparametersareinwhichgroupcanbefoundintheparameterlist.
 C(0)!P(0)=
X readvaluesofallparametersofchannelX
 C(0)!P(0)=X.Y readvaluesofallparametersingroupYofchannelX
 C(0)!P(0)=‐1 readvaluesofallparametersofallchannels
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OtherspecialactionscanbetriggeredbyP(0):
 C(0)!P(0)=‐2 opena
logfile,readallparametervaluesonallchannels,andclosethefile.
 C(0)!P(0)=‐3 bringthemainwindowtothefront
 C(0)!P(0)=‐4 bringtheFLOW‐BUSconfigurationwindowtothefront
 C(0)!P(0)=‐6 bringthePolltimewindowtothefront
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C(0)!P(0)=‐7 bringtheSystemsettingswindowtothefront
 C(0)!P(0)=‐8 restartthecommunication
 C(0)!P(0)=‐9 terminateFlowDDE
 C(0)!P(0)=‐10 minimizeFlowDDE 
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P(1) is the read status information channel. When FlowDDE is reading data from the FLOW ‐BUS, all status/error
messages will be
 send to this parameter. When the value of this parameter is 0, everything is OK, otherwise will
containthestatus/errormessage.
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P(2)isthewritestatusinformationchannel.WhenaclientapplicationsendsdatatoFlowDDEandFlowDDEsendsthe
valuestotheFLOW‐BUS,anystatus/errormessageswillbe
sendtothisparameter.Whenthevalueofthisparameter
is0,everythingisOK,otherwisewillcontainthestatus/errormessage.
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5.2.2 Parameter0
Similar to theway parameter 0 ofchannel0canbeused to read parameters fromanychannel,parameter0 of any
channelcanbeusedtoreadparametersfromthatchannel:
 C(X)!P(0)=Y readvalueofparameterYofchannelX
 C(X)!P(0)=Y‐Z readvalues
ofparametersYtoZofchannelX
 C(X)!P(0)=GROUPY readvaluesofallparametersingroupYofchannelX
 C(X)!P(0)=ALL readvaluesofallparametersofchannelX
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