Siemens Sinumerik 840D sl Function Manual page 273

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S T(FRDP - -> FSDP)
Sum of the transfer times from:
-- T(FRDP --> DB18) or T(FRDP --> SPL--INSE)
-- Processing time by the user--specific SPL program.
-- T(DB18 --> FSDP) or T(SPL--OUTSE --> FSDP)
The following applies for the subsequent tables of the PLC and NCK processing
times:
S Values in italics can increase by up to 500 ms due to delays in the communica-
tion path between the NCK and PLC.
S F_DP clock cycle: 500 ms 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. The maximum F_DP
clock cycle that has occurred is displayed in MD10091
$MN_INFO_SAFE_SRDP_CYCLE_TIME.
S OB1 clock cycle: 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.
S IPO: IPO clock cycle is formed from MD10050 basic system clock cycle and
MD10070 interpolator clock cycle.
S 0...m * IPO clock cycle: 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.
S 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 milli-
seconds.
S The error response for system errors (see Alarm 27355) and F_DP communica-
tion errors: Sequence Number and CRC (see alarm 27350 / 27351 SN and
CRC) is realized in the F_DP clock cycle in which the error is identified.
S The error response for F_DP communication error TIMEOUT (see Alarm 27350
and 27351 TO) is realized in the F_DP clock cycle in which the parameterized
timeout (FSDP: MD13335 $MN_SAFE_SDP_TIMEOUT, FRDP: MD13345
$MN_SAFE_RDP_TIMEOUT) is exceeded.
S 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 500 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--F_DP layer in the OB40 context are delayed by the permitted
maximum of 500 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.
© Siemens AG 2015 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
7.4 Safety- -related CPU- -CPU communication (F_DP communication)
Connecting Sensors/Actuators
7-273