Connecting Sensors/Actuators7.2 Connecting I/O via PROFIsafe05.087-219© Siemens AG 2008 All Rights ReservedSINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition 0...m * IPO: This time component only becomes applicable if delays are in-curred on the PLC side. In this case, in each subsequent IPO clock cycle, it isdetermined as to whether the PLC is ready to communicate again. OB40_INT is the maximum permissible time to initiate the interrupt on the NCKside up to execution of the PROFIsafe software and a ready signal to the NCK.The time is mainly determined by the run time (propagation time) of the F driverimplementation on the PLC side and the PLC user program to be run–throughin the OB40 context. These times typically lie in the vicinity of a few millisec-onds. The specified maximum times are theoretical values; it is extremely improbablethat they actually occur in practice.Reason:– It is improbable that the run time of the PLC–F driver is delayed – in theOB40 context – by the maximum time of 50 ms. The reason for this is thatthe interrupting organizational blocks (OB8x) only have such long run timesin extremely few cases.– For the theoretical value, it would be necessary that two consecutive runs ofthe PLC–PROFIsafe master driver in the OB40 context are delayed by thepermitted maximum of 50 ms – this is extremely improbable.– The maximum time of 150 ms for the user program is not reached in any ofthe applications relevant in practice.PLC processing timesTime:: T(FDI–>DB18)Formula 2 * PST + 1 * OB1Max. times 2 * 50 ms + 1 * 150 ms 250 msTypical times 1) 2 * 16 ms + 1 * 30 ms 62 msTime:: T(DB18–>FDO)Formula 2 * PST + 1 * OB1Max. times 2 * 50 ms + 1 * 150 ms 250 msTypical times 1) 2 * 16 ms + 1 * 30 ms 62 msTime:: T(FDI–>FDO)Formula 4 * PST + 2 * OB1Max. times 4 * 50 ms + 2 * 150 ms 500 msTypical times 1) 4 * 16 ms + 2 * 30 ms 124 ms1) Typical times: PST = 16 ms; OB1 = 30 ms
