Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 80)

Chapter
Programming Block-Transfers 5
5 -6
Block-Transfer Programming Tips
Remember these block-transfer programming tips:
Block lengths PUSHed for CALLs 4 and 5 must equal the
corresponding lengths on your BTW/BTR instructions in the PLC
ladder logic.
If a BTW appears first in your ladder logic, put a CALL 3 or 6 first in
your BASIC program. If a BTR appears first in your ladder logic, put a
CALL 2 or 7 first in your BASIC program.
If your application requires bi-directional block-transfers, you can use
CALL 6 or 3 and CALL 7 or 2 anywhere in your program at any time
interval, if you:
- Use an equal number of each type.
- Alternate their use (e.g. CALL 6, CALL 7, CALL 6, CALL 7).
If your application requires a one way block-transfer
(all write-block-transfers or all read-block-transfers),
use only the associated CALLs ( 4 and 3 or 6; 5 and 2 or 7).
Tip