5.1
Frequent Errors in the User Program
The system program can detect effects of errors in the user program,
faulty operation of the CPU, or errors in the system program
processing.
The following list describes errors that occur most frequently during
the start-up of the user program. You can avoid these errors by doing
the following when you write you STEP 5 program.
••
When specifying byte addresses for I/Os, make sure that the
corresponding modules are plugged into the central controller or
the expansion unit.
••
Make sure that you have provided correct parameters for all
operands.
••
Be careful when changing function blocks. Check to see that the
FBs/FXs are assigned the correct operands and that the actual
operands are specified.
••
Make sure that outputs, flags, timers, and counters are not
processed in several locations in the program with operations that
counteract each other.
••
Make sure that timers are scanned only once per cycle (e.g., A T1).
••
Make sure that all data blocks called in the program exist and are long
enough.
••
Check to see if all blocks called are actually in the memory.
••
If required by other blocks (e.g. standard function blocks),
scratchpad flags should be saved by interrupt-driven and
time-controlled programs and loaded again when these program
sections have been completed.
Frequent Errors in the User Program
CPU 948 Programming Guide
5 - 4
C79000-G8576-C848-04
Summary of Contents for CPU 948
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Page 32: ...Contents CPU 948 Programming Guide 2 2 C79000 G8576 C848 04 ...
Page 72: ...Data Blocks CPU 948 Programming Guide 2 42 C79000 G8576 C848 04 ...
Page 74: ...Contents CPU 948 Programming Guide 3 2 C79000 G8576 C848 04 ...
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Page 200: ...Contents CPU 948 Programming Guide 5 2 C79000 G8576 C848 04 ...
Page 308: ...Contents CPU 948 Programming Guide 7 2 C79000 G8576 C848 04 ...
Page 324: ...Examples of Parameter Assignment CPU 948 Programming Guide 7 18 C79000 G8576 C848 04 ...
Page 326: ...Contents CPU 948 Programming Guide 8 2 C79000 G8576 C848 04 ...
Page 370: ...Addressable System Data Area CPU 948 Programming Guide 8 46 C79000 G8576 C848 04 ...
Page 372: ...Contents CPU 948 Programming Guide 9 2 C79000 G8576 C848 04 ...
Page 486: ...Contents CPU 948 Programming Guide 11 2 C79000 G8576 C848 04 ...
Page 522: ...PG Functions via the S5 Bus CPU 948 Programming Guide 11 38 C79000 G8576 C848 04 ...
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Page 538: ...Contents CPU 948 Programming Guide 13 2 C79000 G8576 C848 04 ...
Page 546: ...List of Key Words CPU 948 Programming Guide Index 6 C79000 G8576 C848 04 ...