Response Times - Siemens SINUMERIK 840D sl Function Manual

Connecting sensors and actuators
8.2 Connecting I/O via PROFIsafe
END_STRUCT;
8.2.10

Response times

The response times listed here refer exclusively to the internal processing of the signals by
the F-master. The following apply:
● T(FDI → DB18) or T(FDI→ SPL-INSE)
The transfer time from the input area of the F-DI module to the input interface of the PLC-
SPL or NCK-SPL
● T(DB18 → FDO) or T(SPL-OUTSE → FDO)
The transfer time from the output interface of the PLC-SPL or NCK-SPL to the output area
of the F-DO module.
● T(FDI → FDO)
Sum of the transfer times from:
T(FDI → DB18) or T(FDI → SPL-INSE)
Processing time by the user-specific SPL program.
T(DB18 → FDO) or T(SPL-OUTSE → FDO)
The following applies for the subsequent tables of the PLC and NCK processing times:
● Values in
between the NCK and PLC.
● PST = 50 ms (PST = PROFIsafe clock cycle) is the permanently implemented maximum
time to detect error-free communications between the NCK and PLC. A STOP response
(STOP D/E) is initiated if this time is exceeded.
● OB1 = 150 ms is the maximum time set as standard in the PLC-CPU to monitor the user
level. The PLC goes into the STOP state if this time is exceeded.
● 0...m * IPO: This time component only becomes applicable if delays are incurred on the
PLC side. In this case, in each subsequent IPO clock cycle, it is determined as to whether
the PLC is ready to communicate again.
● OB40_INT is the maximum permissible time to initiate the interrupt on the NCK side 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-driver implementation on the PLC
side and the PLC user program to be run-through in the OB40 context. These times typically
lie in the vicinity of a few milliseconds.
● The specified maximum times are theoretical values; it is extremely improbable that they
actually occur in practice.
Reason:
It is improbable that the run time of the PLC-F driver is delayed - in the OB40 context - by
the maximum time of 50 ms. The reason for this is that the interrupting organizational blocks
(OB8x) only have such long run times in extremely few cases.
For the theoretical value, it would be necessary that two consecutive runs of the PLC-
PROFIsafe master driver in the OB40 context are delayed by the permitted maximum of
50 ms - this is extremely improbable.
The maximum time of 150 ms for the user program is not reached in any of the applications
relevant in practice.
206
italics can increase by up to 50 ms due to delays in the communication path
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated