Communications
configuring
System- and communication configuring D7-SYS - SIMADYN D
3-151
Edition 12.2003
3.16 SIMATIC
P-bus
coupling
The
FM 458
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 is
passive on the P bus
, i.e. the FM 458 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
,
EXM 448
expansion modules can only be accessed from
the FM 458 (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, 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 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If the memory module is inserted or withdrawn, or is not available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, EXM 448
Addresses
Diagnostic
interrupts
