Technical data

Explanation of the ISTACK
screen
DEPTH Information level of the ISTACK when more than one error has
occurred:
DEPTH 01 = last cause of stop to occur
DEPTH 02 = next to last cause of stop to occur
......
DEPTH13 = ...... (maximum depth)
Information about the error The following table contains information about the ISTACK IDs with
which the statement in the user program can be found which caused
the CPU to change to the STOP mode.
Information about the error
ISTACK ID Meaning
OP-REG
Operation register:
Contains machine code (first word) of the
instruction processed last in an interrupted
program processing level (see list of
operations, list of machine codes).
BLK-STP
Block stack pointer:
contains the number of elements entered
in the block stack at the time when
the interruption of this processing level
occurred
LEVEL Z
Specifies the level of program processing that was
interrupted
Z : 0002: COLD RESTART
0004: CYCLE
0006: TIME INTERRUPT / 5 sec (OB 18)
0008: TIME INTERRUPT / 2 sec (OB 17)
000A: TIME INTERRUPT / 1 sec (OB 16)
000C: TIME INTERRUPT / 500 ms (OB 15)
000E: TIME INTERRUPT / 200 ms (OB 14)
0010: TIME INTERRUPT / 100 ms (OB 13)
0012: TIME INTERRUPT / 50 ms (OB 12)
0014: TIME INTERRUPT / 20 ms (OB 11)
0016: TIME INTERRUPT / 10 ms (OB 10)
0018: TIMED JOB
Table 5-6 Meaning of the ISTACK IDs concerning the point of error
5
Control Bits and Interrupt Stack
CPU 928B Programming Guide
C79000-B8576-C898-01
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