Profibus System Integration PDF 4.03MB - Schneider Electric

Dimensioning of the Profibus MasterA Profibus master can manage a maximum of 124 slaves, but system constraintstypically reduce this capacity. Examples of these constraints are discussed below:Example: For our calculations, we consider that an instrument uses on average 10bytes in entry (2 measurements) and 5 bytes at exit for posting. The number of inputdata being more important than the number of output data, the figure for input datawill be used for the calculations.The Profibus Coupler TSX PBY100 on PremiumAccording to the type of Premium platform the number of module TSX PBY100 variesfrom 0 to 5.The table hereafter indicates the number of module suitable for connection ProfibusDP master on each type of Premium platforme.Number of master stations per PLCPremium platform0 TSX P57 104/154/16341 TSX P57 204/254/2634/TSX PCI 57 2043 TSX P57 304/3634/354/PCI 57 3544 TSX P57 454/46345 TSX P57 554/5634Module TSY PBY100 has an interface I/O for cyclic exchanges of 242 words inputand 242 words output.Because TSX PBY100 data consisting of 2 measurements are assigned to distinctwords, we thus have the 5 bytes of a measurement assigned to 3 words.Consequently, if we consider a median number of 2 measurements per instrument,we thus have 6 words of input and 3 words of output per instrument.Please note that this mapping is from the SyCon bus configuration tool.For a TSX PBY100 module, the maximum number of instruments which one canconnect will be equal to 242 (I/O data size) divided by 6 (words of entries for aninstrument) = 40 instruments maximum.Please note that for this calculation, we use the most important data number,specifically the number for the input data.41