Iskra MC350 - Appendix C: Profibus Protocol; Profibus Overview; Structure of the Input;Output Telegram

APPENDIXC:PROFIBUSPROTOCOL
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Measuringcentres
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MC320,MC330,MC350&MC350H ‐ User’sManua
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APPENDIXC:PROFIBUSPROTOCOL
Profibusoverview
IskraMC350HsupportsProfibusDP‐V0communicationprotocol.Upto32slavedevicescouldbeconfiguredinto
thesingleProfibusnetworkat the speedsupto12 Mbps at rangesupto100meters.Eachdevicecouldbe
configured as a slave device providing wide range of measuring data to the Profibus master. Profibus
communicationisenabledoveraRS485SUB‐D9‐pinconnectorwithoutinternalterminalresistors.Thisrequires
theuseofthestandardProfibuscablewithbusterminationonit(390/220/390Ohms).
TosetProfibusconnectionsettingscouldbedoneorviaMiQenSettingsStudioorviaLCDscreen.TouseLCD
screenpleasegoto:
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MainmenuSettingsCommunication
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MainmenuSettingsCommunicationwhere4Profibussettingsareavailable(slaveaddress‐defaultsetto
125, address locking bit underaddress status, diagnostic option and parametrization option). To start using
MC350HontheProfibusnetworkonlysettingoftheProfibusslaveaddressisnecessary.Thereisnosettingfor
thebaudrate,becausetheMC350Hhasbaudrateautodetectionandthebaudrateisalwayssetautomaticallyby
theProfibusMaster.ThesamesettingsparametersareavailablealsounderMiQenmenu:SettingsGeneral
Communication.
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Structureoftheinput/outputtelegram
WhenIskraMC350HProfibusenterstheDataExchangeoperationmodethenstandardSRD(SendandRequest
Datawithacknowledge)telegramsareexchangedbetweenMasterdeviceandMC350Hdevice.Iskradefinesone
outputtelegrams(mastertoslave)and4inputtelegrams(slavetomaster),toprovidedatainformationbeing
exchanged.Outputtelegramisusedtowritedataintotheoutputmoduleregisters.Andtheinputtelegramsare
usedtoreadoneoffourmoduleswithmeasuringdata.Telegramsaredefinedonthedatasectionfield(data
fieldupto244Byteslong)insidetheSDRmessagestructure.Thepurposeoftelegramsdefinitionistoprovide
exchangeofmeasurementsdatafromMC350HtotheMasterdeviceandtocontrolMC350Houtputsfromthe
Masterdevice.
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MC350Houtputtelegramisdefinedas:
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MastertelegramtotheSlave Meaning/contents Value
Headerbyte0 TelegramID
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ormodulenumberofthedata
segmenttoberequested
1‐5
Headerbyte1 reserved‐notusedatthistime 
Headerbyte2 controlbyte WRXXXXXXDU
Headerbyte3 reserved‐notusedatthistime 
Databytes4‐128 upto124bytesofuserdata userdatabeingexchanged
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