Siemens Simatic S7-300 CPU 31xC Series - Table 10-8 BF2 BUSF LED Is Lit

Debugging functions, diagnostics and troubleshooting
10.6 Diagnostics using status and error LEDs
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
10-17
To correct or avoid error on the PROFINET Interface - BF2/ BUSF LED is lit
Table 10-8 BF2/ BUSF LED is lit
Possible errors Reaction based on the
example of a CPU
To correct or avoid error:
• Bus problem (no physical
connection to a subnet/switch)
• Wrong transmission speed
• Full duplex mode not set
Call of OB 86 (when CPU is
in RUN mode). CPU
switches to STOP if OB 86
is not loaded.
• Check the bus cable for a short-circuit or
break.
• Check that the module is connected to a
switch and not to a hub.
• Check that data are being transmitted at 100
Mbps and in full duplex mode.
• Analyze the diagnostic data. Edit the
configuration.
To correct or avoid error on the PROFINET Interface of an IO Controller - BF2/ BUSF LED flashes
Table 10-9 BF2/ BUSF LED flashes on a PROFINET IO controller
Possible errors Reaction based on the
example of a CPU
To correct or avoid error:
• Failure of a connected IO device
• At least one of the assigned IO
devices cannot be addressed
• Faulty configuration
Call of OB 86 (when CPU is
in RUN mode).
CPU switches to STOP if
OB 86 is not loaded.
• Check that the Ethernet cable is connected to
the module or whether the bus is interrupted.
• Wait until the CPU has completed its startup. If
the LED does not stop flashing, check the IO
devices or evaluate its diagnostic information.
• Verify that the configured device name
matches its actually assigned name.
See also
Evaluating the SF LED in case of software errors (Page 10-11)
Evaluating the SF LED in case of hardware errors (Page 10-13)