Siemens SIMATIC Manual page 92

Digital modules
3.11 Digital input module SM 321; DI 16 x 24 VDC; with hardware and diagnostic interrupts (6ES7321-7BH01-
0AB0)
Diagnostic interrupt
When diagnostic interrupts are enabled, incoming error events (initial occurrence) and
outgoing error events (error is cleared) are reported by means of an interrupt.
The CPU interrupts user program execution in order to process diagnostic interrupt OB82.
You can call SFC51 or 59 in OB82 in the user program to view detailed diagnostics data
output by the module.
Diagnostics data remain consistent until the program exits OB82. The module acknowledges
the diagnostic interrupt when the program exits OB82.
Hardware interrupt
SM 321; DI 16 x DC 24 V can trigger a hardware interrupt for each channel group at the
positive, negative, or both edges of a signal transition.
Program each channel group separately. The parameters can be changed at any time (in
RUN mode in the user program.)
Active hardware interrupts trigger hardware interrupt processing in the CPU (OB40) and
interrupt execution of the user program or of object classes with lower priority in the CPU.
You can define the response of the AS to signal edge transitions in the user program of
hardware interrupt OB40. The module acknowledges the hardware interrupt when the
program exits the hardware interrupt OB.
The module can save one interrupt per channel to the stack. If no higher priority classes are
pending processing, the CPU processes the buffered interrupts (of all modules) in the order
of their occurrence.
Hardware interrupt lost
A "Hardware interrupt lost" diagnostic interrupt is generated if a successive interrupt is
triggered at the channel previously saved to the stack and which has not yet been processed
by the CPU.
The CPU does not register any further interrupts at this channel unless it has completed
processing of the queued interrupts of the same channel.
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
92
Data type
WORD B#16#0
DWORD see the figure
below
Description
Address of the interrupt-triggering module
Indication of the interrupt-triggering inputs
Manual, 06/2017, A5E00105505-AJ
S7-300 Module data