Fault type/LED Cause of fault Correction
External fault
EXTF Diagnostics LED
Auxilliary voltage 1L+/1M is not connected or 24
VDC encoder supply is short circuited
Correct connection
5.2 VDC encoder supply short circuited or over‐
loaded
Correct connection
5 V encoder signals faulty (wire breakage, short
circuit, cable missing)
Correct connection
Initiation of a diagnostics interrupt
All faults, except for the fault in the EPROM test can initiate a diagnostics interrupt if you have
enabled the diagnostics interrupt in the relevant parameter assignment screen form. You will
nd out which fault has caused the LED to light up from the diagnostic data records DS0 and DS1.
The assignment of the diagnostics data records DS0 and DS1 is described in the next section.
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 o 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.
Errors and diagnostics
11.3 Initiation of diagnostics interrupts
Counter module FM 450-1
92 Equipment Manual, 03/2022, A5E03648739-AC
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