Siemens SIMATIC ET 200AL System Manual page 501

The start information of the organization block includes information on which channel of the
analog input module triggered the hardware interrupt.
Note
Violation of two limits
If two limits are violated at the same time, limit 1 is always signaled first, followed by limit 2.
The figure below shows the assignment to the bits of the local data double word 8.
Image 5-2
Structure of the additional interrupt information
Table 5- 4
Data block name
USI
(User Structure Identifier)
The channel that triggered the hardware interrupt follows.
Channel
The error event that triggered the hardware interrupt follows.
Event
Analog input module AI 4xU/I/RTD 4xM12 (6ES7144-5KD00-0BA0)
Manual, 03/2016, A5E32350124-AC
Start information of the organization block
Structure of USI = W#16#0001
Contents
W#16#0001
B#16#00 to
B#16#03
B#16#03
B#16#04
B#16#05
B#16#06
Interrupts/diagnostics alarms
Comment
Additional interrupt info for hardware inter-
rupts of the I/O module
Number of channel which triggered the event 1
Low limit 1 violated
High limit 1 violated
Low limit 2 violated
High limit 2 violated
5.2 Interrupts
Bytes
2
1
31