5.17
Diagnostics functions of analog modules
Programmable and non-programmable diagnostic messages
We distinguish between programmable and non-programmable diagnostic messages.
You only obtain programmable diagnostic messages if you have enabled the diagnostics using
the relevant parameters. You perform parameter assignment in the "Diagnostics" tab in
STEP
7.
The analog module always provides non-programmable diagnostic messages, irrespective of
the enable state of diagnostics functions.
Reactions to diagnostic messages in STEP 7
Actions initiated by diagnostic messages:
● The diagnostic message is entered in the diagnostics of the analog module, forwarded to
the CPU and can be read out by the user program.
● The error LED on the analog module is lit.
● If you have set "Enable Diagnostic Interrupt" in
STEP 7, a diagnostic interrupt is triggered
and OB 82 is called.
Reading diagnostic messages
You can read detailed diagnostic messages using SFCs in the user program (refer to the
appendix "Diagnostic data of signal modules").
You can view the cause of the error in
STEP 7 in the module diagnostics (refer to the online
help for STEP 7).
Diagnostic message in the measured value of analog input modules
All analog input modules return the measured value 7FFF
H
as a reaction to errors, irrespective
of parameter settings. This measured value indicates either overflow, error, or a disabled
channel.
Diagnostics using the INTF and EXTF LEDs
Some analog input modules indicate faults by means of their two fault LEDs INTF (internal
fault) and EXTF (external fault). The LEDs go out when all the internal and external faults have
been eliminated.
Refer to the specifications of the modules to find out which analog input modules have these
fault LEDs.
Diagnostic messages of the analog input modules
The table below gives an overview of the diagnostic messages for the analog input modules
with diagnostics capability.
Analog modules
5.17 Diagnostics functions of analog modules
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