Display "Existing Channel Error" In The Diagnostics Interrupt Ob (Ob82); Display Of The The Dp Slave History - Siemens SIMATIC NET S7-400 Equipment Manual

Operation, diagnostics and maintenance

4.2 Display "Existing channel error" in the diagnostics interrupt OB (OB82)

Bus fault of the type "bus short-circuit"
If there is a bus short-circuit, this can cause one of the following responses on the PROFIBUS
subnet:
• Failure of the bus line
• Failure of stations / of all stations
The response can be recognized by evaluating with OB86.
Note
Bus fault statistics
With STEP 7 special diagnostics, you can read out the information from the entry PROFIBUS >
Statistics > Bus fault statistics If there is a bus fault, it is possible that different bus fault
events are registered in the statistics even though it appears that identical bus faults have
occurred.
4.2 Display "Existing channel error" in the diagnostics interrupt OB
(OB82)
Display "Existing channel error" in the diagnostics interrupt OB (OB82)
Under certain circumstances, the "Existing channel error" flag may not be set (false) although
there is a channel error.
This reaction corresponds to the current response on the PROFIBUS interfaces with SIMATIC.
Remedy: You can read out detailed up-to-date diagnostics information using the diagnostics
function "Read system diagnostics" SFC13 (read out standard diagnostics).
4.3

Display of the the DP slave history

Restricted display of older diagnostics data in STEP 7 special diagnostics
Diagnostics data can be read out in STEP 7 special diagnostics. With an additional button, you
can also have older diagnostics data displayed alongside the current diagnostics data.
With the CP 443-5 Extended (DX05), it is possible that not all the older diagnostics events can
be displayed due to the limited buffer size - the display of underlying intermediate states is
then omitted.
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Equipment Manual, 01/2023, C79000-G8976-C162-10
CP 443-5 Extended