CPU modules
4.2 CPU module CPU550/CPU551
SIMATIC TDC hardware
System Manual, 08/2017, A5E01114865-AL
91
4.2.4
Status and fault displays
The configured number of the CPU module (1...20) is displayed in normal operation. Faults
are indicated by a letter that informs you of the type of fault.
Slow alternation between the lit and dark state of the 5x7 dot matrix LEDs is referred to as
flashing in the following table.
Table 4- 6
Operating and fault states of CPU550/CPU551
Display
Operating and fault states
Can be
cleared with
S1
1... 20
Configured number of the CPU module in normal operation.
User program is running
No
A
User error
User program is running
Diagnostics event, user-defined by means of USF function block
Yes
All 35 dots off Initialization phase:
User program is not running
Individual initialization phases during startup are indicated by means
of consecutive numbers.
No
All 35 dots
flashing
Module failure:
User program is not running
•
Hardware failure => replace CPU550/CPU551
•
Fatal software error => contact the Hotline
No
0
Initialization error
User program is not running
Diagnostics should start at the CPU module that was the first to dis-
play fault message “0”.
•
Flashing "0" Faults on this module
•
Permanent "0": Faults on a different module
If none of the CPU modules can be identified as having been the first
one, then of those which display a "0", the one inserted to the ex-
treme left should first be selected.
No
b
Monitoring error
User program is running
Low-priority errors during initialization that allow the start of normal
operation and that are detected in the background process, e.g.: For
example,
•
missing, low backup battery
•
Missing program memory module
•
Fan failure
•
Invalid floating value (substitute value will be used)
Yes
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