Configuring The Startup Options - Siemens Simatic S7 Series System Manual

PLC device configuration
6.1 Configuring the operation of the PLC system
6.1.7

Configuring the startup options

Click the Startup node of the system block (Page 115) dialog to configure startup options for
the PLC.
CPU mode
From this dialog you can select the mode for the CPU after a startup. You have one of the
following three choices:
● STOP
The CPU shall always enter STOP mode after a power up or restart (default selection).
● RUN
The CPU shall always enter RUN mode after a power up or restart. For most applications,
especially those where the CPU operates independently without a connection to
STEP 7-Micro/WIN SMART, the RUN startup mode selection is the correct choice.
● LAST
The CPU shall enter the operating mode that existed prior to the last power up or restart.
This selection can be useful during program development or commissioning. Be aware
that a running CPU can enter STOP mode for a variety of reasons, such as the failure of
an expansion module, occurrence of a scan watchdog timeout, the insertion of a memory
card, or an erratic power up event. Once the CPU enters STOP mode, it will continue to
enter STOP mode each time the CPU powers up. You must restore the CPU back to
RUN mode (Page 36) from STEP 7-Micro/WIN SMART.
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System Manual, 09/2015, A5E03822230-AC
S7-200 SMART