Siemens SIMATIC ET 200AL System Manual page 174

Diagnostics interrupt, starting at byte x+8
The figure below shows the structure of the diagnostics interrupt starting at byte x+8.
Figure 5-6
Diagnostics interrupt from the modules, starting at byte x+14
The channel error entries start from byte x+14. A channel fault entry is 6 bytes long and can
follow 8 times starting at byte x+14.
If you read the channel faults with an SFB or SFC, then 38 channel diagnostics are possible.
Figure 5-7
Interface module IM 157-1 DP (6ES7157-1AA00-0AB0)
Manual, 12/2016, A5E32100641-AD
Interrupts, error messages, diagnostics and system alarms
Structure starting at byte x+8
Structure starting from byte x+14
5.2 Interrupts
31