Technical data

Appendix 5: Example "ISTACK Evaluation"
This (simplified) example illustrates how to evaluate the ISTACK.
For more detailed information, you should also refer to Section 5.3
"Control Bits and the Interrupt Stack".
Ready to start? The CPU has interrupted cyclic program processing and has changed
to the stop mode.
Error analysis To find the cause of the interruption, select the programmer online
function "output ISTACK".
The control bits then appear on the PG screen as shown below:
The "X"s in the control bits indicate the current operating status of the CPU
(>>STP<< ), and certain characteristics of the CPU are marked (OB 1
loaded, single processor mode, 16 KW user memory etc.). In the top
line the cause of the stoppage is indicated as
STP-BEF. It is assumed
that you have not programmed an STP operation in your STEP 5 user
program. This means that the stoppage was caused by a stop operation
from the system program because an error OB was not loaded. The
identifier
LZF is marked in the bottom line.
CONTROL BITS
>>STP<< STP-6
ANL-6
RUN-6 EINPROZ BARB OB1GEL FB0GEL OBPROZA OBWECKA
ANL-2 NEUZU MWA-ZULNEUSTA
X
X
X
X
XX
X
X
X
X
X
MWA AWA
FE-STP BARBEND PG-STP STP-SCH STP-BEF MP-STP
>>ANL<<
>>RUN<<
32KWRAM
16KWRAM
URL-IA
FE-22
FE-6 FE-5 FE-4 FE-3 L Z F REG-FE DOPP-FE
PEU BAU ZYK QVZ ADF WECK-FESTUE-FE
MOF-FE RAM-FE DB0-FE DB1-FE DB2-FE KOR-FE
STP-VER ANL-ABB UA-PG UA-SYS UA-PRFE UA-SCH
8KWRAM KM-AUS KM-EIN DIG-EIN DIG-AUSEPROM
URGELOE
DX0-FE
NAU
BCF
Appendix 5: Example "ISTACK Evaluation"
CPU 928B Programming Guide
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