Diagnostics And Troubleshooting - Siemens SIMATIC S5-100U System Manual

S5-100U
5

Diagnostics and Troubleshooting

5.1 Indication of Errors by LEDs
The programmable controller's operator panel will show you if your device is not functioning
correctly (see Table 5-1).
Error Indication
CPU in STOP
Red LED lights
CPU in STOP
Red LED flashes
CPU in RUN
Green LED lights
Faulty operation
If both LEDs light, your programmable controller is in the START-UP operating mode.
5.2 CPU Malfunctions
5.2.1 "ISTACK" Analysis Function
The interrupt stack is an internal CPU memory area where the causes of malfunctions are stored. If
there is a malfunction, a bit in the respective byte of the memory area is set. Using the pro-
grammer, you can read out the contents of this memory area byte-by-byte.
Calling the ISTACK
The call is made through the programmer menu in the STOP operating mode.
Refer to your programmer manual for the key sequence.
Note
Only ISTACK bytes 1 through 6 can be output in the RUN mode. There is no cause for
an interrupt to force the CPU to go into the STOP mode. The control bits are output in
bytes 1 through 6.
EWA 4NEB 812 6120-02b
Table 5-1. Error Indication and Error Analysis
CPU malfunction
Use the programmer to execute an interrupt analysis
(see section 5.2).
Error when loading or backing up the program
Use the programmer to execute an interrupt analysis
(see section 5.2).
Program error
(see section 5.3)
or
I/O fault
Execute a fault analysis
(see section 5.4).
Diagnostics and Troubleshooting
Error Analysis
5-1