Principles of analog modules
5.8 Diagnostics of analog modules
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ
295
5.8 Diagnostics 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 diagnostics at the
relevant parameters. Program these functions in the "Diagnostics" parameter block in
STEP 7
.
The the analog module always provides non-programmable diagnostic messages,
irrespective of the enable state of diagnostic functions.
Reactions to a diagnostic message in
STEP 7
Actions initiated by diagnostic messages:
● The diagnostic message is written to the diagnostics buffer of the analog module, and is
then passed to the CPU.
● The error LED on the analog module is lit.
● When "Enable Diagnostics Interrupt" is set in STEP 7, the system triggers a diagnostic
interrupt and calls OB82.
Reading diagnostic messages
You can read detailed diagnostic messages in the user program using SFCs.
Viewing the cause of error
You can view the cause of the error in the module diagnostics data in
STEP 7
(refer to the
STEP 7
Online Help.)
Diagnostic message included 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.
Diagnostic message using the SF LED
Diagnostics-capable analog modules indicate errors by means of their SF LED (group error
LED). The SF LED lights up when the analog module has generated a diagnostic message.
It goes dark after all error states are cleared.
See also
Programming analog modules (Page 294)
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