Siemens simatic s7-400 FM 450-1, User Manual, Page: 109 / 130

Errors and diagnostics
11.5 Operator error
Counter module FM 450-1
Manual, 02/2014, A5E03648739-02
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11.3 Initiation of diagnostics interrupts
What is a diagnostics interrupt?
If the user program is to respond to an internal or external fault, you can set the parameters
for a diagnostic interrupt that will break off the cyclical program of the CPU device and calls
the diagnostics interrupt OB (OB 82).
Which events can initiate a diagnostic interrupt?
The following events can initiate a diagnostic interrupt:
● The external auxiliary 1L+/1M voltage is faulty.
● 5.2 VDC encoder supply short circuited or overloaded.
● The module parameters are incorrectly assigned.
● Watchdog timeout
● RAM defective
● Hardware interrupt lost
● Signal A faulty (wire breakage, short circuit, cable missing)
● Signal B faulty (wire breakage, short circuit, cable missing)
● Signal N faulty (wire breakage, short circuit, cable missing)
Enabling the diagnostic interrupt
You disable or enable the interrupts for the module and you choose whether the module is to
initiate a diagnostic interrupt and/or a hardware interrupt.
Responses to a diagnostic interrupt
If an event occurs that can trigger a diagnostic interrupt, the following happens:
● The diagnostic information is stored in the diagnostic data records DS0 and DS1 on the
module.
● An error LED lights up.
● The diagnostic interrupt OB is called (OB82).
● Diagnostic data record DS0 is entered in the start information of the diagnostic interrupt
OB.
● The count process continues unchanged.
If no OB82 has been programmed, the CPU goes into STOP.