S5-115F ManualError Diagnostics5 Error DiagnosticsThe S5-115F operating system detects errors which can occur in connection with any of thefollowing:• Hardware• Programming (STEP 5)• Configuring (e.g. PLC parameters)• Data handling (e.g. wrong address setting on interface modules).The S5-115F offers the following methods of displaying error messages:• ISTACK (Interrupt stack)• BSTACK (Block stack)• COM 115F - plaintext5.1 Interrupt AnalysisWhen malfunctions occur, the operating system sets various ”analysis bits” that can be scannedwith the programmer using the ”ISTACK” function. LEDs on the CPU also report some mal-functions.5.1.1 ”ISTACK” AnalysisThe interrupt stack (ISTACK) is an internal memory area of the CPU where malfunction reports arestored. When a malfunction occurs, the appropriate bit is set.Use a programmer to read this memory byte by byte.NoteYou cannot read the ISTACK when the PLC is in the ”RUN” mode.EWA 4NEB 811 6149-025-1
