S5-95F
Testing the User Program and Storing It on the Memory Submodule
14.2
Interrupt Analysis with the Programmer
When malfunctions occur, the operating system sets various "analysis bits"; you can then scan
these bits using the programmer's "ISTACK" function.
14.2.1 The "ISTACK" Analysis Function
The interrupt stack is located in internal memory. The S5-95F uses the ISTACK to flag the cause of
a fault. When a fault occurs, a bit is set in the relevant byte of the ISTACK.
The interrupt stack can be read out via the programmer.
Invoking the ISTACK
The ISTACK is invoked via the programmer menu while the PLC is at "STOP".
Refer to the programmer manual for the keystroke sequence.
ISTACK Updating
The S5-95F updates the ISTACK
•
when the PLC goes from "RUN" to "STOP" without actuation of the mode switch
(RUN
STOP)
•
when the S5-95F is switched from "STOP" to "RUN" but still remains at "STOP"
Redisplay the contents of the ISTACK on the programmer to ascertain the current cause of error.
The tables on the following pages show:
•
The control bits set in the ISTACK
•
The causes of error flagged in the ISTACK
•
The system data words in which the ISTACK flags are stored and
•
Descriptions of the abbreviations and error flags used.
EWA 4NEB 812 6210-02
14-5
