RFC 4072S
36 / 272
PHOENIX CONTACT 108580_en_02
The minimum F_WD_Time that can be set can be determined for each communication con-
nection using the following equation:
Since the iSPNS 3000 cycle and the PROFINET cycle run asynchronously with one another,
the iSPNS 3000 cycle must be included twice in the total when determining the minimum
F_WD_Time, once as the “HAT” and again as the “internal bus runtime”. The external bus
runtime is based on the relevant times of the PROFINET configuration.
For the example configuration in Section “Example of a PROFINET/PROFIsafe configura-
tion with PROFINET controller/F-Host” on page 88, taking into consideration the values
below, the minimum F_WD_Time OUT for communication with the F-Device
AXL F PSDO8/3 1F is calculated as follows:
WARNING: Avoid possible danger that may be caused by the safety function
being triggered too late
Make sure that the maximum permissible values for F_WD_TIME IN
max
and F_WD_TIME
OUT
max
are not exceeded (see Section “Determining SFRT
max
and
F_WD_Time IN
max
/F_WD_Time OUT
max
” on page 29).
F_WD_Time
min
> DAT + 2 x Bus + HAT [3]
F_WD_Time
min
> DAT + 2 x (external bus runtime + internal bus runtime) + HAT
F_WD_Time
min
> DAT + 2 x (external bus runtime + T
ZSPNS
) + T
ZSPNS
F_WD_Time
min
> DAT + 2 x external bus runtime + 3 x T
ZSPNS
[4]
T
ZSPNS
= 5 ms Cycle time of the safety-related controller (here:
iSPNS 3000)
T
ZPNIO
= 8 x 3 ms Monitor time: PROFINET update time x monitor
factor (see Figure 2-5 on page 33).
T
DAXLFBKPN
= 1 ms Update rate of the AXL F BK PN (or
AXL F BK PN TPS) PROFINET bus coupler.
T
ZAXLLB
= 10 µs Update rate of the Axioline F local bus with one
device
DAT
PSDO
= 1.5 ms Processing time of the AXL F PSDO8/3 1F
T
Bus
= T
ZPNIO
+ 1 x T
DAXLFBKPN
+ 2 x T
ZAXLLB
T
Bus
= 24 + 1 x 1 ms + 2 x 0 ms
T
Bus
= 25 ms
Due to the low value this time is negligi-
bly small in the following calculation for
the given example. For larger local bus
configurations, consider corresponding
times in the calculation.
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