Siemens SENTRON VL Series System Manual page 165

Local diagnostics event
A DP slave has the option of reporting a local diagnostics event to the DP master via the
Layer-2 message frame priority "high-prio" of the Data_Exchange-Response frame in
Layer 2. Then the DP master requests the diagnostics data from the DP slave for evaluation.
If there are no current diagnostics events pending, the Data_Exchange-Response frame has
a "low-prio" ID. The diagnostics data of a DP slave can also be requested at any time by a
DP master without special reporting of diagnostics events.
Diagnostic messages with S7 stations
Modules with diagnostics capability in the distributed I/O are able to report events such as a
partial station failure, wire break in signal modules, short-circuit/overload of an I/O channel,
or failure of the load voltage supply, via a diagnostic interrupt. In the case of a coming or
outgoing diagnostic interrupt, the CPU operating system calls the organization block for
diagnostic interrupt OB 82. If a diagnostic interrupt occurs and OB 82 is not programmed, the
CPU enters STOP mode.
Coming/outgoing event
A failure (coming event) or the return (outgoing event) of a DP slave is reported by the
operating system of the S7-CPU via OB 86. If OB 86 has not been programmed, the S7 CPU
switches to STOP mode when the event occurs.
3WL/3VL circuit breakers with communication capability - PROFIBUS
System Manual, 03/2011, A5E01051353-02
7.3 Functional sequences/description of functions
Data transfer to the PLC
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