Diagnostics With Leds; Status And Error Displays - Siemens SIMATIC S7-300 Hardware And Installation Manual

11.5 Diagnostics with LEDs

Introduction
Diagnostics with LEDs is an initial tool for error localization. Usually you evaluate the
diagnostic buffer for further error localization. The buffer contains plain text information on
the error that has occurred. For example, it contains the number of the associated error OB.
You can then generate this OB to prevent the CPU status changing to STOP.
For further information on status and error displays,
see the Status and error displays section of the appropriate CPU Data Reference
Manual.
Status and error displays of all CPUs
Table 11-2

Status and error displays

LED
SF 5 VDC FRCE RUN
mode
LED LED LED LED off
off off off
LED On X (see LED off
off the
descri
ption)
On On X LED off
X On X LED off
X On X LED off
X On X Flashes
(2 Hz)
X On X Flashes
(0.5 Hz)
On On X X
X X On X
Description of status X:
This status has no effect on the current CPU function.
S7-300 Programmable Controller Hardware and Installation
A5E00105492-02
Testing functions, Diagnostics and Fault Elimination
Description
STOP
LED off CPU power supply missing.
Remedy:
Check whether the power supply module is connected to
mains and switched on. Check whether the CPU is
connected to the power supply module and switched on.
On The CPU is in STOP mode.
Remedy: Start the CPU.
On The CPU is in STOP mode as a result of error. Remedy:
refer to the tables below, evaluate the SF LED
Flashes The CPU requests memory reset.
(0.5 Hz)
Flashes The CPU executes memory reset.
(2 Hz)
On The CPU is in start-up mode.
On The CPU was halted by a programmed break point. For
details refer to the Programming Manual Programming
with STEP 7 .
X Hardware or software error Remedy: refer to the tables
below, evaluate the SF LED
X You have activated the Force function For details refer to
the Programming Manual Programming with STEP 7 .
11-7