Profibus System Integration PDF 4.03MB - Schneider Electric

Application LayersPROFIBUS-PA guarantees the interchangeability and the compatibility of fieldinstruments from multiple manufacturers. Functions and parameters of the equipmentare described using functional blocks universally recognized within the industry.A manufacturer willing to offer a PA Profile compliant device must, implement theinternal device structure, with Physical, Transducer and Function Block objects asshown in the diagram below.SensorPhysical blockFunctionblockoutput valueof transmetterMasteror PLCPhysical Block (PB)The Physical Block stores a certain number of device-specific hardware and softwaregeneral parameters (such as model designation, manufacturer ID, software version,and serial number. It also offers some basic device control functions such as Writeprotection, Blocking operator access to the device, and Factory reset. There is onlyone Physical block in a PA device.Transducer Block (TB)A Transducer Block operates as a type of interface between the sensor or actuatorlevel, and the Function Block. It performs signal linearization and calibration, ifrequired, and initiates actuation in final control elements. Accordingly, it gives accessto the corresponding parameters.A multi-sensors device will have the same number of Transducer Blocks as itsnumber of sensors.Function Block (FB)A Function Block stands as a link between the communication bus and thecorresponding Transducer Function Block. The Function Block performs the scalingof the operated value. It inherits one or more input or output parameters, analog ordiscrete. It also contains some other parameters, and can execute additional taskssuch as engineering units calculations, limits survey, etc.18