Functionality Of The Spl Input/Output Data - Siemens SINUMERIK 840D sl Function Manual

Connecting sensors and actuators
8.2 Connecting I/O via PROFIsafe
Formula
Maximum times
Typical times
with: PST: PROFIsafe clock cycle
PST = n * IPO; with n = 1, 2, 3, ...
Typical times: PST = 18 ms; IPO = 6 ms; OB40_INT = 2 ms
1)
This time is valid for the case: IPO = 8 ms, n=3 ⇒ PST = 24 ms; (maximum times for values n > 2)
2)
This time is valid for the case: PST = n * IPO = 25 ms
3)
This information always applies for communication via PROFINET. The special features of the
various bus systems do not need to be taken into account, except for the time, determined by
the set baud rate and the bus expansion level.
8.2.11

Functionality of the SPL input/output data

The functionality of the SPL input/output data is exclusively defined by the user (machinery
construction OEM) within the scope of the PROFIsafe communication
The SPL programs of NCK-SPL and PLC-SPL are not executed synchronously (from a time
perspective). Brief differences in the output data of the two SPL programs (NCK: $A_OUTSE,
PLC: $A_OUTSEP) can occur due to the runtime differences in the SPL programs.
In order that the PLC and NCK use identical F-net data for the two-channel generation of a
PROFIsafe telegram, the SPL output data are interchanged alternating, between the two
channels (PLC: $A_OUTSEP and NCK: $A_OUTSE) in each PROFIsafe clock cycle - and
before sending, are AND'ed with one another. For safety reasons, this is the reason that the
user must select the functionality of SPL input/output data so that the value "0" corresponds
to the safe state of the functionality represented by this data. Only then can it be ensured that
the corresponding function is only activated at the F-slave output if the function has actually
been activated in both SPL programs (PLC-SPL and NCK-SPL).
SPL input/output data
For safety reasons, this is the reason that the functionality of an SPL input or output data is
selected so that the value "0" corresponds to the safe state of the functionality represented
by this data.
As a result of the synchronization of the SPL output data described above, it cannot be ensured
that when several SPL output data are changed simultaneously - taking into account in the
SPL program - that these are also transferred consistently (in time) in the PROFIsafe telegram.
If, in a user application, several SPL output data are interpreted as a contiguous bit pattern, it
must therefore be taken into account that intermediate values can briefly occur.
Example:
208
2 * PST + PST + 0...m * IPO + OB40_INT
100 ms +25 ms + 50 ms + 50 ms
2 * 18 ms + 18 ms + 2 ms
1)
WARNING
225 ms
3)
56 ms
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated