Installation and Commissioning

Connecting SignalsInstallation and CommissioningProfibus DP:Cables according to Profibus DP specification should be used for connections betweenthe I/O unit DSQC 352 and the external Profibus DP bus.3.3 Interference eliminationInternal relay coils and other units that can generate interference inside the controllerare neutralised. External relay coils, solenoids, and other units must be clamped in asimilar way. Figure 25 illustrates how this can be done.Note that the turn-off time for DC relays increases after neutralisation, especially if adiode is connected across the coil. Varistors give shorter turn-off times. Neutralising thecoils lengthens the life of the switches that control them.+24 V DC+0 VThe diode should be dimensioned for thesame current as the relay coil, and a voltageof twice the supply voltage.The varistor should be dimensioned for thesame energy as the relay coil, and a voltage oftwice the supply voltage.+24 V DC, or AC voltage +0 VRCR 100 ohm, 1WC 0.1 - 1 µF> 500 V max voltage125 V nominal voltageFigure 25 Examples of clamping circuits to suppress voltage transients.3.4 Connection typesI/O, external emergency stops, safety stops, etc., can be supplied on screwed connectionsor as industrial connectors.DesignationX(T)XPXSScrewed terminalMale (pin)Sockets (female)32 Product Manual IRB 1400