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Profibus System Integration PDF 4.03MB - Schneider Electric

Profibus System Integration PDF 4.03MB - Schneider Electric

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Software PLC designIntroductionFor each function, a DFB is associated with a corresponding DDT. In the examplesbelow, four main functions are presented:• Measure treatment DFB• Diagnosis DFB, standard and detailed• Adjustment DFB• Acyclic read/write DFBOther DFBs not detailed here are presented in the Implementation Phase chapter.Measure Treatment DFBReminder: A measure on <strong>Profibus</strong> PA is mapped on array of 5 bytes. This measureis compound of a measure value and its status.Below is an example for a temperature sensor:Input byteProcessParameterAcces mode Comment/Data format Factory default units0, 1, 2, 3 Temperature Read32 Bit floating decimalpoint (IEEE-754)° C4StatusTemperaturePerformed functionRead -This DFB is designed to extract the measured value in real format and to restore themeasurement status.This DFB is common to all platforms.DescriptionAnaloginput data12Measurevalue3Status fortheprocess4Status fordisplaying47

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