Profibus System Integration PDF 4.03MB - Schneider Electric

Bus terminationsPROFIBUS DPFor RS 485 communication support, PROFIBUS DP requires a bus termination to beinstalled at each end of any cable segment, in order to minimize signal reflections.Station 1 Station 1VP (6)RxD/TxD-P (3) (3) RxD/TxD-PDGND (5)(5) DGNDData line390 ΩRxD/TxD-P (3)VP (6)(6) VP220 ΩData lineVP RxD/TxD-P (8) (8) VP RxD/TxD-PRxD/TxD-P (8)ShieldingProtectivegroundProtectiveground390 ΩDGND (5)Wiring Bus terminationA bus termination is provided by a combination of three resistors. 5 Vdc and DataGround potential references are generally supplied by the device terminating the bussegment, while the resistors are usually included in the Bus Terminating connector.This means that only 2 data wires – Line A and Line B respectively) establish thephysical link between the bus cable and the terminating device, as well as for anyintermediate device.PROFIBUS PAPA+100 Ω +/- 2%1 µF +/- 20%PA-APROFIBUS MBP (PA) communication cabling also requires a specific type of bustermination, installed at each end of the any cable segment, in order to minimizesignal reflections. This bus termination is accomplished with a combination of oneresistor and one capacitor.There are several possible forms for a PROFIBUS PA bus termination, depending onthe cabling type. This termination can be implemented as a termination connector, orintegrated in a tee unit, or integrated in a device or a segment coupler.32