Evaluation Of A Hardware Interrupt - Siemens S7-300 Operating Instructions Manual

Programming without SFB 52 and SFB 53
D.8 Evaluation of a hardware interrupt
D.8

Evaluation of a hardware interrupt

If FM 352 triggers a hardware interrupt, the following information is available in the
OB40_POINT_ADDR variable (or in the corresponding variable of a different hardware
interrupt OB):
Table D- 1
Byte
0
1
2
3
You can see the cause of the interrupt in byte 1.
Cam: Evaluate bytes 2 and 3 according to the table.
Lost hardware interrupts
If the hardware interrupt OB is still busy processing a hardware interrupt, the module
registers all subsequent hardware interrupt events. If an event occurs again before the
hardware interrupt could be triggered, the module triggers a "hardware interrupt lost"
diagnostic interrupt.
212
Content of double word OB40_POINT_ADDR
Bit 7 Bit 6
0 0 0
0 0 0
Cam 7 on Cam 7 off Cam 6 on Cam 6 off Cam 5 on Cam 5 off Cam 4 on Cam 4 off
Cam 3 on Cam 3 off Cam 2 on Cam 2 off Cam 1 on Cam 1 off Cam 0 on Cam 0 off
Bit 5 Bit 4 Bit 3
0 0
0 0
Operating Instructions, 05/2011, A5E01071724-03
Bit 2 Bit 1
0 0 0
Cam 0 0
FM 352 electronic cam controller
Bit 0