Allen-Bradley 1747-SN - Bidirectional Alternating Repeating Block Transfer

5–49RIO Block Transfer
Publication 17476.6 - July 1996
Bidirectional Alternating Repeating Block Transfer
The following rungs demonstrate a bidirectional alternating
repeating block transfer. Using these rungs ensures the block
transfer requests are executed in the order in which they are sent to
the queue. This example also ensures that the BTR and BTW
repeatedly alternate. The XIO conditions prevent the BTR and BTW
from queuing simultaneously. The BT’s continue as long as the
ladder rungs are scanned.
Rung 2:0
CONFIGURE THE BT OPERATION TYPE, LENGTH AND RIO ADDRESS (R,G,S IN DECIMAL) AT
POWER–UP. BIT N7:50/7 MUST BE SET TO A ”1” TO INDICATE A BTR AND N7:53/7 MUST
BE A LOGICAL ”0” TO INDICATE A BTW OPERATION.
| |
| |
| |
| POWER–UP BTR |
| BIT CONTROL |
| S:1 +COP–––––––––––––––+ |
|––––] [––––––––––––––––––––––––––––––––––––––––––––––+–+COPY FILE +–+–|
| 15 | |Source #N7:50| | |
| | |Dest #M0:1.100| | |
| | |Length 3| | |
| | +––––––––––––––––––+ | |
| | | |
| | | |
| | | |
| | BTW | |
| | OPERATION | |
| | +COP–––––––––––––––+ | |
| +–+COPY FILE +–+ |
| |Source #N7:53| |
| |Dest #M0:1.200| |
| |Length 3| |
| +––––––––––––––––––+ |
Rung 2:1
COPY THE BTR STATUS AREA TO AN INTEGER FILE ONLY WHEN A BTR IS IN PROGRESS.
THIS STATUS DATA WILL THEN BE USED THROUGHOUT THE PROGRAM AND WILL LIMIT THE
NUMBER OF M–FILE ACCESSES
| |
| |
| |
| BTR |
| PENDING BTR STATUS |
| B3 +COP–––––––––––––––+ |
|–+––––] [–––––+––––––––––––––––––––––––––––––––––––––––––+COPY FILE +–|
| | 0 | |Source #M1:1.100| |
| | | |Dest #N7:60| |
| | | |Length 4| |
| | | +––––––––––––––––––+ |
| | | |
| | | |
| | | |
| | CHECK BTR | |
| | STATUS | |
| | B3 | |
| +––––] [–––––+ |
| 2 |