Monitoring the execution
time of OB 39
The execution time of OB 39 is monitored by the system program. If
execution takes longer than 2.55 seconds (fixed value), the system
program detects a cycle time error; it then calls the error OB, OB 26,
and then processes OB 39 again from the beginning. If a cycle time
error occurs again, an ISTACK depth > 5 causes an ISTACK overflow
(reaction: see following paragraph).
Reaction to an
error in OB 39
If an error occurs in OB 39 or in a handling block called in OB 39
(e.g. QVZ), the system program calls the appropriate error
organization block. After this has been executed, the program
processing is continued in OB 39. If the error OB does not exist,
OB 39 is executed again from the beginning. (Exception: with QVZ,
KB and errors in the self test there is no reaction).
If further errors occur, an ISTACK depth > 5 causes an ISTACK
overflow:
the system program aborts program execution (OB 39 is no longer
called), the CPU however remains in the SOFT STOP mode.
Data are not reset
If cyclic execution has already taken place in the RUN mode, the
values of counters, timers, flags and the process image are retained
during the transition to the stop mode.
Real-time clock
The real-time clock continues to run. It is updated in the RS area at
10 ms intervals.
BASP signal
The BASP (disable output command) signal is active. This disables all
the digital outputs (exception: in the test in multiprocessor operation
and with the PG function "force outputs", BASP is not active - refer to
Section 10.1.8).
ISTACK
If a user program was processed prior to the stop mode, information is
entered in the interrupt stack (ISTACK) providing information about
the cause of the interruption.
Timer processing in OB 38/39
While OB 38/39 is being executed, the processing of timers and
counters is stopped. If necessary, timer information must be
processed from system data area RS 96 to RS 99 or with OB 121
or OB 150.
STOP Mode
CPU 948 Programming Guide
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C79000-G8576-C848-04
Содержание CPU 948
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Страница 72: ...Data Blocks CPU 948 Programming Guide 2 42 C79000 G8576 C848 04 ...
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Страница 324: ...Examples of Parameter Assignment CPU 948 Programming Guide 7 18 C79000 G8576 C848 04 ...
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Страница 370: ...Addressable System Data Area CPU 948 Programming Guide 8 46 C79000 G8576 C848 04 ...
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Страница 404: ...Operations with the Base Address Register BR Register CPU 948 Programming Guide 9 34 C79000 G8576 C848 04 ...
Страница 486: ...Contents CPU 948 Programming Guide 11 2 C79000 G8576 C848 04 ...
Страница 522: ...PG Functions via the S5 Bus CPU 948 Programming Guide 11 38 C79000 G8576 C848 04 ...
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Страница 546: ...List of Key Words CPU 948 Programming Guide Index 6 C79000 G8576 C848 04 ...