Configuring
4-6 Application Module FM 458-1 DP - User Manual
A5E01078222-02 Edition 03.2009
4.3 Coupling to the SIMATIC S7-CPU
The FM 458-1 DP has a RAM memory (128 Kbytes) which can be used
to connect it to a P bus. Data can be exchanged with one SIMATIC S7-
CPU via this P-bus memory.
The FM 458-1 DP is passive on the P bus, i.e. the FM 458-1 DP cannot
directly access other modules of the SIMATIC station.
There are 3 ways to transfer data to the SIMATIC CPU:
4 bytes can be received from the SIMATIC-CPU using a process
interrupt
128 bytes can be sent and received via SIMATIC I/O accesses
extremely large data quantities can be sent and received using data
blocks/sets
The EXM 438-1, EXM 448/EXM 448-1/EXM448-2expansion modules can
only be accessed from the FM 458-1 DP (via the FM-internal LE bus);
they have no direct connection to the P bus.
The start addresses of the I/O, under which a SIMATIC CPU can address
the I/O range of the FM 458-1 DP, are configured in HW Config. The
addresses for inputs and outputs can differ.
HW Config menu: “Edit/Properties/Addresses”
Default: 512 (decimal; for inputs and
outputs)
The FM 458-1 DP also sends diagnostic interrupts to the SIMATIC-CPU,
independent of what has been configured, in the following situations.
Transition into the statuses
“initialization error “
“system error “
“user stop “
“RUN“
If the memory module is inserted or withdrawn, or is not available
P-bus memory
Accessing
EXM 438-1,
EXM 448
Addresses
Diagnostic
interrupts
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