Siemens S7-300 - 8.6 SM 326; DO 10 x DC 24 V;2 A (6 ES7326-2 BF01-0 AB0)

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S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP
A5E00203919-01
9-29
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As an alternative to the MPI interface, you can program the CPU or execute the
Status and Modify functions of the PG via the PROFIBUS-DP interface. To do so,
you must enable these functions when configuring the CPU as a DP slave in
STEP7.
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The use of Status and Control function via the PROFIBUS-DP interface extends
the DP cycle.
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CPU 31x-2 DP operating as a DP slave provides a transfer memory for PROFIBUS
DP communication. All data exchange between the CPU as DP slave and the DP
master takes place via this transfer memory. You can configure up to 32 address
areas for this function.
That is, the DP master writes its Data to these intermediate memory address areas
and the CPU reads these data in the user program, and vice versa.
Transfer memory
in the address
area
PROFIBUS
I/Q I/Q
CPU as DP slave
DP master
Figure 9-9 Transfer memory in the CPUs 31x-2 DP acting as DP slave
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In 67(3, configure the I/O address areas:
• You can configure up to 32 I/O address areas.
• Maximum length per address area is 32 bytes.
• You can configure a maximum of 244 input bytes and 244 outputs bytes.