Siemens Simatic S7-300 CPU 31xC Series User Manual

Debugging functions, diagnostics and troubleshooting
10.6 Diagnostics using status and error LEDs
S7-300, CPU 31xC and CPU 31x: Installation
10-14 Operating Instructions, Edition 08/2004, A5E00105492-05
10.6.5 Status and Error Indicators: CPUs with DP Interface
Description of the BUSF, BUSF1 and BUSF2 LEDs
Table 10-5 BUSF, BUSF1 and BUSF2 LEDs
LED Meaning
SF 5 VDC BUSF BUSF1 BUSF2
On On On/
flashes
- - PROFIBUS DP interface error.
Remedy: See table below
On On - On/
flashes
X Error at the first PROFIBUS DP interface of CPU 317-2 DP.
Remedy: See the table below
On On - X On/
flashes
Error at the second PROFIBUS DP interface of CPU 317-2 DP.
Remedy: See the tables below
Description of status X:
The LED can assume the On or Off state. This status, however, is irrelevant for the current
CPU function. For example, the states Force On or Off do not influence the CPU STOP
status
Table 10-6 BUSF LED is lit
Possible errors CPU reaction Remedies
• Bus fault (hardware fault).
• DP interface error.
• Different transmission rates in
multiple DP master mode.
• If the DP slave / master interface is
active: short-circuit on the bus.
• With passive DP slave interface:
transmission rate search, i.e. there
are no other active nodes on the
bus (a master, for example)
Call of OB86 (when CPU is in RUN
mode). CPU switches to STOP if OB86
is not loaded.
• Check the bus cable for short-circuit
or breaks.
• Analyze the diagnostic data. Edit
the configuration.

Siemens Simatic S7-300 CPU 31xC Series Specifications

General

Series	S7-300 CPU 31xC
Power Supply	24 V DC
Communication Interfaces	MPI, PROFIBUS DP
Programming Languages	LAD, STL, FBD, SCL
Operating Temperature	0°C to +60°C
Memory	48 KB - 512 KB
Dimensions	40 x 125 x 130 mm (varies by model)