Siemens SIMATIC S5-90U System Manual page 107

S5-90U/S5-95U
Reading and Resetting the Diagnostic Byte
In the central program, you can read in and evaluate the data stored in the diagnostic byte using
binary operations (e.g., A I 35.0) or load operations (e.g., L IB 35).
Example
The diagnostic byte is
to be evaluated within
the program.
Note
Reset the counter condition code bits and the interrupt condition code bits to "0" after
the current program processing.
operations R I 35.0 through 35.7. Note that this operation is executed only if RLO = "1".
The next time there is a counter or interrupt call up, the respective bits will be reset
(ORed).
5.2 LED Error Display
The programmable controller's operator panel will show you if there are any internal malfunctions
(see Table 5-1).
Table 5-1. Display and Analysis of Errors and Faults
Display
PLC in STOP
Red LED is lit
PLC in STOP
Red LED is flashing
PLC in RUN
Green LED is lit
Faulty operation
If both LEDs are lit, your programmable controller is in the "RESTART" operating mode.
EWA 4NEB 812 6115-02b
STL
.
.
.
If bit "0" is set to "1" in the diagnostic byte, then
A I 35.0
signal "1" is assigned to output 32.1.
= Q 32.1
BE
Resetting in the program is possible using the bit
Analysis
PLC malfunction
Use the programmer to execute an interrupt analysis
(see Section 5.3)
Error when loading or saving the program
Use the programmer to execute an interrupt analysis
(see Section 5.3)
Program error
or
I/O fault
Execute a fault analysis
(see Section 5.5)
Diagnostics and Trouble Shooting
Explanation
5-3