Example
You want the data block start address (DBA = 4152H in DB 17, length = 256
DW) to be shifted by 32 data words relative to the end of the block.
:C
DB
17
open DB 17
:L
KB
32
shift value as constant
:JU
OB
180
call OB 180: shift access window
After OB 180 has been called, the data word, for example, at address 4
1543H can no longer be addressed with DW 35 but only with DW 3 etc. (see
Fig. 6-3).
Due to the change made at the same time in the DBL register, error monitoring
is not affected: the operation T DW 223 is permitted, while T DW 224/L DW 224
causes an error.
By calling OB 180 again, the DBA can be increased again (and the DBL
reduced). The operation C DB 17 returns the block to its original settings
(DBA = 4152H, length 256 DW).
If DB 17 had a length of 256 data words for example, you could then no
longer access DW 256 and DW 257 using STEP 5 operations. By shifting the
DBA resgister by 16, data words 256 and 257 can be addressed as "DW 240"
and "DW 241".
Continued on next page
OB 180: Variable Data Block Access
CPU 948 Programming Guide
C79000-G8576-C848-04
6 - 55
Summary of Contents for CPU 948
Page 10: ...Contents CPU 948 Programming Guide 1 2 C79000 G8576 C848 04 ...
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 ...
Page 154: ...Contents CPU 948 Programming Guide 4 2 C79000 G8576 C848 04 ...
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 ...
Page 524: ...Contents CPU 948 Programming Guide 12 2 C79000 G8576 C848 04 ...
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 ...