Debugging functions, diagnostics and troubleshooting
10.6 Diagnostics using status and error LEDs
S7-300, CPU 31xC and CPU 31x: Installation
10-10
Operating Instructions, Edition 08/2004, A5E00105492-05
10.6.2
Status and error displays of all CPUs
Table 10-2 Status and error displays
LED
Meaning
SF
5 VDC
FRCE
RUN
STOP
Off
Off
Off
Off
Off
CPU power supply missing.
Remedy: Check whether the power supply module is
connected to mains and switched on.
Off
On
X (see the
description)
Off
On
The CPU is in STOP mode.
Remedy: Start the CPU.
On
On
X
Off
On
The CPU is in STOP mode as a result of error.
Remedy: refer to the tables below, evaluation of the SF
LED
X
On
X
Off
Flashes
(0.5 Hz)
The CPU requests memory reset.
X
On
X
Off
Flashes
(2 Hz)
The CPU executes memory reset.
X
On
X
Flashes
(2 Hz)
On
The CPU is in startup mode.
X
On
X
Flashes
(0.5 Hz)
On
The CPU was halted by a programmed break point.
For details, refer to the Programming Manual
Programming
with STEP 7
.
On
On
X
X
X
Hardware or software error
Remedy: refer to the tables below, evaluation of the SF
LED
X
X
On
X
X
You enabled the Force function
For details refer to the Programming Manual
Programming
with STEP 7
.
X
X
Flashes (2 Hz) X
X
Node flashing test was activated.
Flashes Flashes Flashes
Flashes Flashes Your CPU has an internal system error. The procedure is
as follows:
1. Set the mode selector switch to STOP.
2. Perform POWER ON/OFF.
3. Read the diagnostics buffer with STEP 7.
4. Contact your local SIEMENS partner.
Description of status X:
This status is irrelevant for the current CPU function.
Reference
•
Details on the OBs and on SFCs required for their evaluation can be found in the
STEP 7
Online Help and in the Manual System Software for S7-300/400 - System and Standard
Functions.