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Functions
4.8 Monitoring functions of the CPU
4.8
Monitoring functions of the CPU
Monitoring and messages
In the CPU, control system blocks monitor the correct execution of the user program. If a system
block detects an error, the system block triggers a defined reaction.
The table shows the events and possible causes:
Event
Time error
Diagnostic interrupt
Pull/plug alarm
CPU device message
Program execution mes‐
sage
I/O failure message
Execution abort
The table shows which LED display is activated by certain events:
LED displays
ER
CTRL ER/MT
X1 ER/MT, X2 ER/MT, X5 ER/MT
System diagnostic options are available as well.
32
Possible cause
Monitoring of the CPU's runtime system has detected significant delays. The
controller is temporarily or permanently overloaded. The response times of
the controller are significantly slowed down.
A component of the controller or an IO device reports a diagnostic event.
The CTRL ER/MT LED lights up from the first, incoming diagnostic interrupt
and goes out with the last, outgoing diagnostic interrupt.
A configured component of the controller or an I/O device has been pulled
or plugged. When an incorrect component is plugged in, the error display
(ER LED) remains on. The plugging of a correct or permissible component
resets this error event.
A CPU-internal event has been detected. The triggering event and the cause
are entered in the diagnostics buffer.
Error while updating the process image. One or more components are not
available.
Failure of a PROFINET IO subsystem or a PROFIBUS DP segment.
A programming error was detected while executing the user program.
Event
•
Time error
•
Diagnostic interrupt
•
Pull/plug alarm
•
CPU device message
•
Program execution message
•
I/O failure message
•
Execution abort
•
Diagnostic interrupt
•
Diagnostic interrupt
•
Pull/plug alarm
•
I/O failure message
Equipment Manual, 11/2022, A5E51584364-AA
CPU 4168-H
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