Siemens S7-300 Installation And Operating Manual page 57

Diagnostics LEDs of the F-SMs
LED
SF (red)
SAFE (green)
The following applies to the SM 326; DI 24 x DC 24V, SM 326; DO 8 x DC 24V/2A PM, SM
326; F-DO 10 x DC 24V/2A PP and SM 336; F-AI 6 x 0/4 ... 20 mA HART:
a flashing of the SF-LED in safety mode means a request for depassivation.
Additional LEDs are described in the chapters of the respective modules.
Diagnostic interrupt
The fail-safe signal modules trigger a diagnostic interrupt when a fault is detected (for
example, a short circuit), provided this diagnostic interrupt is enabled. The F-CPU interrupts
execution of the user program (standard or safety) or of the lower priority classes and
executes diagnostic interrupt OB82.
Assigning the diagnostic interrupt enable parameter
The diagnostic interrupt is disabled by default. Enable the diagnostic interrupt in the object
properties dialog of the F-SM in
Analog modules (Page 181)).
Special information regarding diagnostic messages
All module-specific diagnostic messages, their possible causes, and corresponding
corrective measures are described in the module chapters.
These chapters also define which diagnostic messages must be assigned, and which are
displayed on a channel-specific basis.
Reading diagnostic messages
Use
● From the diagnostic buffer of the CPU or the diagnostic buffer of the module (
● In the standard user program by calling SFC59 (see Appendix
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
Channel or module
fault
On
On
STEP 7
to read the cause of the problem
function "Diagnose Hardware").
modules
and the System and Standard Functions reference manual).
Safety mode
Defective
module
On
Off
HW Config
, (see chapters for Digital modules (Page 73) and
Fault reaction and diagnostics
6.2 Diagnosis of Faults of F-SMs
Standard mode
Channel or module fault Defective module
On
Off
Diagnostic data of signal
On
Off
STEP 7
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