Technical data

17.7 Calculating the Switch-off and Reaction Times of
the Global I/Os
Calculation of the switch-off times T
so
for the free and
cycle-synchronized modes
The CP 5430 TF/CP 5431 FMS "registers" the failure of a station only after
the switch-off time T
so
has expired. After this time, the CP resets the GP
inputs, i.e. the input bytes assigned to this station are set to the value "0".
The time T
so
depends on the following
- the selected target rotation time and
- the selected data rate.
The diagram shows the switch-off time T
so
(in seconds) as a function of the
target rotation time (TTR; in bit time units).
T
so/s
T
somin
TTR
limit
TTR/
bit time units
1
2
1
2
Explanation of areas
and
:
1
If TTR is less than TTR
limit
, the CP switches off
the failed station at the latest after time T
somin
has elapsed
2
If TTR is greater than TTR ,there is a linear relationship
according to the equaiton (TTR in bit time units, data rate in
bps, T in seconds):
T =----------------*TTR
24
data rate
limit
so
so
Fig. 17.13 Switch-off Time T
so
(in seconds) as Function of the Target Rotation Time
Appendix B8976060/02
Volume 1 17 - 30