Technical data

If you have a short time-critical user program in which you do not
require structured programming, then program
FB 0. Since you use
the total STEP 5 operation set in this block, you do not require block
calls and can reduce the runtime of your program.
Note
If both OB 1 and FB 0 are programmed, only OB 1 is called by
the system program. If you use FB 0 as the user interface, it must
not contain parameters.
Interrupt points Cyclic program execution can be interrupted at block boundaries by
the following:
•• process interrupt-driven program execution,
•• closed loop controller processing,
•• time-driven program execution.
Note
You can program DX 0 to enable these interruptions to occur at
operation boundaries (see Chapter 7).
Cyclic program execution can be interrupted at
operation boundaries
or aborted completely as follows:
•• if a device or program error occurs,
•• by operator intervention (PG function, stop switch, MP-STP),
•• by the STOP operation.
ACCUs as data storage The arithmetic registers ACCU 1, 2, 3 and 4 of the CPU 928B can be
used as data storage outside the cycle (from the end of one program
cycle to the beginning of the next).
RUN Mode
CPU 928B Programming Guide
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