Siemens SIMATIC S5 Manual page 270

C.1.1 Reaction time t
Definition t
prog
two cases for t
Table C-2 Reaction time t
prog
Reaction time
t for accessing
prog
process image
Application program
At the start of the application program cycle, the process image of the
inputs is transferred from the IM 308-C to the PII.
At the end of the application program cycle, the process image of the
outputs is transferred from the PIO to the IM 308-C.
If you access the process image, t
program.
t for direct access
prog
(load/transfer
commands)
Application program
If you access the dual-port RAM of the IM 308-C directly using
load/transfer commands, reaction time t
ET 200 Distributed I/O System
EWA 4NEB 780 6000-02a
Reaction times in the ET 200 distributed I/O system
prog
is the reaction time of the application program in the CPU. There are
:
prog
Caused by
CPU
Input
data
PII
OB 1
Output
data
PIO
equals the duration of the application
prog
CPU
PII
OB 1 Input
data
L PY 30
:
:
Output
:
data
T PY 30
PIO
prog
IM 308-C
Dual-port RAM
Input data
Output data
IM 308-C
Dual-port RAM
Input data
Output data
is negligible.
Importance
Very important
Negligible
C-3
C