Monitoring Functions Of The Cpu; Monitoring And Error Messages - Siemens SIMATIC S7-400H Manual

Installation of a CPU 41x-H
4.2

Monitoring Functions of the CPU

Monitoring and Error Messages

The CPU hardware and the operating system have monitoring functions that
ensure that the system functions correctly and that there is a defined response to
an error. A number of errors will also produce a response from the user program.
The following table gives you an overview of possible errors, their causes and the
responses of the CPU.
There are also test and information functions available in each CPU that you can
call up with STEP 7.
Type of
Fault/Error
Clock pulse Monitoring of the failure of the processor
failure clock pulse
System standstill
Access error Module failure (SM, FM, CP)
•
Timing error The runtime of the user program (OB1
and all the interrupts and error OBs)
exceeds the specified maximum cycle
time.
•
OB request error
•
Overrun of the start information buffer
•
Time error interrupt
Power supply In the central or distributed I/O rack:
•
module error
At least one backup battery in the
(not power
power supply module is empty.
•
failure)
The backup voltage is missing.
•
The 24 V supply to the power supply
module has failed.
Diagnostics An I/O module with interrupt capability
Interrupt reports a diagnostics interrupt.
Remove/insert Removal or insertion of an SM and
interrupt insertion of an incorrect module type. If the
only inserted SM is removed during STOP
mode of the CPU with default parameter
assignment, the EXTF LED will not light up.
If the SM is inserted again, the LED lights
up briefly.
4-6
Cause of Error Response of the Operating
System
Disabling of the digital outputs by
issuing the "OD" (Output Disable)
signal
"EXTF" LED lights up until the fault is
acknowledged.
In SMs:
•
OB 122 call
•
Entry in the diagnostics buffer
•
In the case of input modules:
Entry of null for the date in the
accumulator or the
process image
In the case of other modules:
•
OB 122 call
"INTF" LED lights up until the fault is
acknowledged.
OB 80 call
If the OB is not loaded: The CPU
goes into STOP mode.
OB 81 call
If the OB is not loaded: The CPU
continues to run.
OB 82 call
If the OB is not loaded: The CPU
goes into STOP mode.
OB 83 call
If the OB is not loaded: The CPU
goes into STOP mode.
Automation System S7-400H Fault-tolerant Systems
Error LED
–
EXTF
INTF
EXTF
EXTF
EXTF
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