Siemens SIMATIC ET 200PA SMART Operating Instructions Manual page 100

Interrupt, error and system messages
8.3 S7 diagnostics
Structure of the channel-related diagnostics
Figure 8-5
Overflow of channel-related diagnoses
If there are more channel-related diagnostics pending than can be shown in the slave
diagnostics, then bit 7 "diagnostics overflow" is set in the station status 3.
The channel-related diagnostics that are not transferred with the frame are not lost. They move
up into the slave diagnostics as soon as other channel-related diagnostic entered up to now in
the diagnostic frame have gone.
Once the "diagnostics jam" has been worked off, bit 7 "Diagnostic overflow" is reset.
100
Structure of the channel-related diagnostics
Operating Instructions, 06/2019, A5E34192013-AB
ET 200PA SMART