Siemens SIMATIC S5 Manual page 284

C.5.4 Calculating reaction time t
What is reaction The reaction time t
time t
? input on a DP slave and the corresponding switching of an output.
R
Components of the
The reaction time t
reaction time t
determined beforehand. The ET 200 distributed I/O system operates on the
R
basis of an asynchronous communication mechanism, so two cases can be
distinguished:
Table C-12 lists the multiplication factors for the reaction times:
Table C-12 Multiplication factors for the reaction times
DP slave (input) t DP slave (input) t
DP master and SINEC L2-DP
bus
DP slave (output) t DP l
ET 200 Distributed I/O System
EWA 4NEB 780 6000-02a
Reaction times in the ET 200 distributed I/O system
R
is the time which elapses between the switching of an
R
is calculated on the basis of the reaction times
R
Typical reaction time and
Worst-case reaction time
Reaction time
Medium
slave slave
( t t) t
slave
t
Factor
(typical)
t 1
I/O
t 1
I/Obus
t 1
IM 318
t 0.5
DP
t 1
cons
t 1.5
prog
t 0.5
DP
t 1
IM 318
t 1
I/Obus
t 1
I/O
=
R
Factor
(worst case)
1
1
(1+t t )
I/Obus/ DP
1
2
2
1
(1+t t )
I/Obus/ DP
2
1
C-17
C