Siemens S7-300 - 1 Product overview; 1.2 Using Fail-Safe Signal Modules

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Product Information on the Manual S7-300 Module Specifications, Edition 11/2002
A5E00213444-02
Hardware interrupt lost
In an interrupt has been buffered for a channel and another interrupt occurs on that
channel before it has been processed by the CPU, a diagnostic interrupt “hardware
interrupt lost” is triggered.
More interrupts on this channel are not acquired until processing of the interrupt
buffered on this channel has been executed.
Interrupt-triggering channels
The start information of OB 40 in the OB40_POINT_ADDR variable indicates
which channel triggered the hardware interrupt. Figure 4 shows the assignment to
the bits of the local data double word 8.
Byte Variable Data type Description
6/7 OB40_MDL_ADDR WORD B#16#0 Address of the
interrupt-triggering module
As of
8
OB40_POINT_ADDR DWORD See
Figure 4
Indication of the
interrupt-triggering inputs
1
Bit no.
3130
29 282726
LD 8
1
LB 8
25 24
Edge change: channel 2
Edge change: channel 0
Edge change: channel 7
LB 11
0
1
Edge change: channel 1
11
LB 10
1
2322
21 201918
1
LB 9
17 16
11
Edge change: channel 10
Edge change: channel 8
Edge change: channel 15
Edge change: channel 9
Reserved
Figure 4 Start information of OB 40: which event triggered the hardware interrupt