Siemens S7-300 - Commissioning the CPU as DP Slave

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S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP
9-28 A5E00203919-01
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Commission CPU 31x-2 DP as a DP slave in the PROFIBUS subnet as follows:
1. Switch on power, but hold the CPU in STOP mode.
2. First, switch on all other DP masters/slaves.
3. Now switch the CPU to RUN mode.
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When the CPU 31x-2x DP is switched to RUN, two independent operating mode
transitions are executed:
• The &38 switches from STOP to RUN mode.
• At the 352),%86'3LQWHUIDFH the CPU starts data transfer with the DP
master.
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The table below shows how CPU 31x-2 operating as a DP slave recognizes
operating state transitions or data exchange interruptions.
Table 9-9 Event recognition by CPUs 31x-2 DP acting as DP slave
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Bus failure interrupt
(short-circuit,
connector
unplugged)
• Call of OB86 with the message 6WDWLRQIDLOXUH
(coming event; diagnostic address of the DP slave, assigned to
the DP slave)
• with I/O access: Call of OB122
(I/O access error)
DP master.
RUN → STOP
• Call of OB82 with the message 0RGXOHHUURU
(coming event; diagnostic address of the DP slave, assigned to
the DP slave; Variable OB82_MDL_STOP=1)
DP master
STOP → RUN
• Call of OB82 with the message 0RGXOH2.
(outgoing event; diagnostic address of the DP slave, assigned to
the DP slave; Variable OB82_MDL_STOP=0)
7LS:
When commissioning the CPU as DP slave, always program OB 82 and 86. This
helps you to recognize and evaluate the respective operating states or data
exchange errors.