Siemens SIMATIC Manual page 102

Digital modules
3.12 Digital input module SM 321; DI 16 x DC 24/125 V; with hardware and diagnostic interrupts (6ES7321-
7EH00-0AB0)
Interrupt-triggering channels
The relevant hardware interrupt-triggering channel is logged in the OB40_POINT_ADDR
variable of the start information of OB40. The figure shows the bit assignments of DWORD 8
in the local data.
Byte Variable
6/7 OB40_MDL_ADDR
starting OB40_POINT_ADDR
at 8
Figure 3-8
102
Data type
WORD
DWORD
Start Information of OB40: which event has triggered the hardware interrupt
Description
B#16#0 Address of the interrupt-triggering module
see the figure Indication of the interrupt-triggering inputs
below
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ