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G DB/GX DX
NOP/display/stop operations
Table 3-10
NOP/display/stop operations
Operation
Operand
N O P 0
N O P 1
B L D
0 to 255
130
131/131/133
255
S T P
CPU 948 Programming Guide
C79000-G8576-C848-04
Generating a data block
The operation G DBx generates a DB data block with the number x
(2 ≤ x ≤ 255) in the user memory of the CPU. The content of the data
block is not assigned the value 0, i.e. the data words can have any
contents.
Before programming this statement, you must store the number of data
words that the new DB is to have in ACCU-1-L. The operation
"G DB" or "GX DX" creates the block header. A data block generated
in this way (without block header) can occupy a maximum of 4091
words. You can generate longer data blocks using OB 125 (refer to
Section 6.5).
If the data block already exists, the length of the DB is not permitted
or there is not enough space in the DB-RAM, the system program
calls OB 34. If this is not loaded, the CPU goes to the stop mode.
The GX DXx operation generates a DX data block in the DB-RAM
and is otherwise the same as G DBx.
Function
–
No operation
No operation
Display generation operation for the PG:
the CPU handles the operation like a no operation
Create blank line with carriage return
Switch over between STL, CSF, LAD
–
At end of cycle or at end of OB 1, CPU changes to soft STOP.
Note
Since the operation STP is only effective at the end of the cycle,
there is no ISTACK entry. The cause of the stoppage is then
difficult to find afterwards.
To make diagnosis easier, you should set an identifier before
calling the STP operation, e.g. a special bit pattern in a diagnostic
DB or use the STEP 5 operation STS (refer to Section 3.5.4).
Basic Operations
3 - 33
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