Siemens SIMATIC ET 200AL, System Manual

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Diagnostics and maintenance
4.8 Diagnostics in the user program
PROFINET with STEP 7
Function Manual, 05/2021, A5E03444486-AL
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2. Evaluation of interrupts
When the error OB (OB 82) is called, the OB's start information provides you with information
on the cause and location of the error. Detailed information on the error event can be
obtained in the error OB using the instruction "RALRM" (read additional interrupt
information).
Num-
ber
Description
① Every error is sent to the IO controller individually as channel diagnostics information in the
form of an interrupt.
② In the IO controller, the module status data is updated automatically and the error OB (OB 82)
is started.
③ In your user program in the error OB (OB 82), the instruction "RALRM" reads the error syn-
chronously from the IO controller without addressing the IO device.
Figure 4-16 Diagnostics with OB 82 and the instruction "RALRM"
Instructions and OBs
You will find information on the instructions and OBs in the STEP 7 online help.