Bidirectional Alternating Block Transfer - Allen-Bradley 1747-SN User Manual

Rung 2:12
MOVE THE VIRTUAL BTW CONTROL WORD TO THE M0 FILE FOR THE SN MODULE WHILE A BTW
IS IN PROGRESS, AND CONTINUE DOING SO UNTIL THE ENABLE, DONE AND ERROR BITS
ARE ALL TURNED OFF, COMPLETING THE HAND–SHAKE PROCESS.
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| VIRTUAL
| BTW ENABLE
| BIT
| N7:53
|–+––––] [–––––+––––––––––––––––––––––––––––––––––––––––––+MOVE
| | 15 |
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| | VIRTUAL |
| | BTW DONE |
| | BIT |
| | N7:64 |
| +––––] [–––––+
| | 13 |
| | |
| | |
| | VIRTUAL |
| | BTW ERROR |
| | BIT |
| | N7:64 |
| +––––] [–––––+
| 12
Rung 2:13
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|–––––––––––––––––––––––––––––––––––––+END+––––––––––––––––––––––––––––––––––––|
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Rung 2:0
CONFIGURE THE BT OPERATION TYPE, LENGTH, AND RIO ADDRESS (R,G,S IN DECIMAL) AT
POWER–UP. 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.
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| POWER–UP
| BIT
| S:1
|––––] [––––––––––––––––––––––––––––––––––––––––––––––+–+COPY FILE
| 15
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Bidirectional Alternating Block Transfer

The following rungs demonstrate a bidirectional alternating 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 block transfer read and block transfer
write alternate. The XIO conditions prevent the BTR and BTW from
queueing simultaneously. The block transfers continue as long as the
XIC precondition bit is true.
RIO Block Transfer
BTW
CONTROL
BITS
+MOV–––––––––––––––+ |
|Source N7:53| |
|
|Dest M0:1.200| |
|
+––––––––––––––––––+ |
BTR
CONTROL
+COP–––––––––––––––+
+–+–|
| |Source #N7:50| | |
| |Dest #M0:1.100| | |
| |Length 3| | |
| +––––––––––––––––––+ | |
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| BTW
| CONTROL
| +COP–––––––––––––––+ | |
+–+COPY FILE +–+ |
|Source #N7:53|
|Dest #M0:1.200|
|Length 3|
+––––––––––––––––––+
Publication 1747 6.6 - July 1996
5–43
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