Siemens SIMATIC S5-115U, User Manual

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S5-115U Manual Technical Description
CPU 941 and CPU 942
Figure 2-4. Schematic Representation of CPU 941 and CPU 942
I/O
modules
The CPU 941 and the CPU 942 both
contain a microprocessor and an ap-
plication-specific integrated circuit
(ASIC). The microprocessor handles all
programmer interface module func-
tions, processes interrupts and substi-
tution operations and controls the
S5 bus. The microprocessor also con-
trols the ASIC that handles high-speed
processing of STEP 5 operations. Be-
sides the operating system memory,
the CPU 941 and CPU 942 also contain
an internal RAM that can be used to
store the control program
(CPU 941: 2 Kbytes
CPU 942: 10 Kbytes).
Operating
system
memory
32 KBytes
Internal
RAM 2
Kbytes
or
10 Kbytes
Control
panel
Controller
for
S5 bus
Memory
submodule
PG
Microprocessor
- processes some
word operations
- controls bus
- handles 1st
serial interface
ASIC
- processes bit
and some word
operations
- processes times
- monitors scan
time
EWA 4NEB 811 6130-02b
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