Siemens SIMATIC ET 200pro - Page 84

Commissioning
8.4 Operating modes of the CPU
CPU 1516pro-2 PN (6ES7516-2PN00-0AB0)
Operating Instructions, 11/2019, A5E35873416-AC
83
No.
Operating mode transitions
Effects
③
STOP → STARTUP The CPU switches to "STARTUP" mode if:
• The hardware configuration and program
blocks are consistent.
• You set the CPU to "RUN" mode via the pro-
gramming device and the mode switch in is
RUN position.
or
• You set the mode switch from STOP to RUN.
The CPU clears the non-retentive
memory, and resets the content of
non-retentive DBs to the start values of
the load memory. Retentive memory
and retentive DB contents are re-
tained.
The 500 most recent entries are re-
tained in the diagnostics buffer.
④
STARTUP → STOP In the following cases the CPU returns from
"STARTUP" to "STOP" mode when:
• The CPU detects an error during startup
• You set the the CPU to "STOP" via the pro-
gramming device or mode switch.
• The CPU executes a STOP command in the
Startup OB.
These operating mode transitions have
no effect on data.
⑤
STARTUP → RUN In the following cases, the CPU goes from
"STARTUP" to "RUN" mode when:
• The CPU has initialized the PLC tags.
• The CPU has executed the startup blocks
successfully.
⑥
RUN → STOP In the following cases the CPU returns from
"RUN" back to "STOP" mode when:
• The CPU recognizes an error that prevents
further execution.
• The CPU executes a STOP command in the
user program.
• You set the the CPU to "STOP" via the pro-
gramming device or mode switch.