F 8628X (0650)
425
6 Parameter used in PROFIBUS-DP Master to
reload a redundant H41q/H51q system
When reloading a redundant H41q/H51q system using a redundant PROFIBUS-DP connec-
tion, the PROFIBUS-DP communication is stopped for a short time after switching over to the
central module that was loaded first.
To avoid failure reactions during the reload procedure, the downtime "t
down
" must be consid-
ered when parameterizing the PROFIBUS-DP Master's redundancy management.
Estimating the downtime t
down
for the PROFIBUS-DP Master
The following formula is used for estimating the downtime:
t
down
< 200 ms + WDT + t
master
t
down
: Within this time, the F 8628X modules cannot communicate.
WDT: H41q/H51q system watchdog time.
t
master
: The amount of time after loading central module 1 that the PROFIBUS-DP Master
requires before the F 8628X communication module can exchange data.
The time "t
master
" is at least 6 bus cycles (polling cycles). The user must deter-
mine the actual number of bus cycles (polling cycles) from the PROFIBUS-DP
master settings or by using a bus analyzer.
The estimate (formula) is only suited for PROFIBUS-DP slave mod-
ules of type F 8628X. The PROFIBUS-DP slave modules must be set
to a fixed baud rate (via switch 2/5-8). When reloading the redundant
H41q/H51q systems, one must ensure that the central module 1 is
loaded first.
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