Siemens SIMATIC S7-300 Series Reference Manual page 94

CPU 31x-2 as DP Master/DP Slave and Direct Communication
2.2 DP Address Areas of the CPUs 31x-2
Address areas of CPUs 31x-2
Address area
DP address area
for I/Os
of these in the I/O
process images
In the input address area, DP diagnostic addresses occupy 1 byte for the DP
master and for each DP slave. Under these addresses, for example, you can call
DP standard diagnostics for the respective nodes (LADDR parameter of SFC13).
The DP diagnostic addresses are specified during configuration. If you do not
specify any DP diagnostic addresses, STEP 7 assigns these addresses, in
decrements starting at the highest byte.
Configuring modules with addresses assigned to the peripheral area
Always configure a module address in a peripheral area either completely inside or
completely outside of the process image. Otherwise, consistency is not ensured
and corrupted data might be generated.
2-4
315-2 DP
1024 bytes 2048 bytes
Bytes 0 to 127 Bytes 0 to 127
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
316-2DP 318-2
8192 bytes
Bytes 0 to 255
(default)
Can be set up to
byte 2047
A5E00111190-01