Directional Non Continuous Block Transfer Example - Allen-Bradley 1747-SN User Manual

Rung 2:0
CONFIGURE THE BTR OPERATION TYPE, LENGTH AND RIO ADDRESS AT POWER–UP. BIT
B3:100/7 MUST BE SET PRIOR TO GOING TO RUN TO INDICATE A BTR OPERATION.
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| POWER–UP
| BIT
| S:1
|––––] [––––––––––––––––––––––––––––––––––––––––––––––––––+COPY FILE
| 15
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Rung 2:1
COPY THE BTR STATUS AREA TO A BINARY FILE WHICH WILL BE USED THROUGHOUT THE
PROGRAM. THIS AVOIDS ADDRESSING THE M1 FILE MULTIPLE TIMES DURING EACH PROGRAM
SCAN. EACH TIME AN INSTRUCTION CONTAINING AN M1 FILE BIT, WORD OR FILE IS
SCANNED BY THE PROCESSOR, AN IMMEDIATE DATA TRANSFER TO THE MODULE OCCURS AND
THEREFORE WILL IMPACT THE OVERALL PROCESSOR SCAN TIME.
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| BTR
| PENDING
| B3
|–+––––] [–––––+––––––––––––––––––––––––––––––––––––––––––+COPY FILE
| | 80 |
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| | CHECK BTR |
| | STATUS |
| | B3 |
| +––––] [–––––+
| 81
Rung 2:2
UNLATCH THE BIT THAT CONTINUES TO CHECK THE BTR STATUS. WHEN A BTR IS
COMPLETE, THE DONE OR ERROR BIT IS SET. THE LADDER PROGRAM MUST THEN UNLATCH
THE ENABLE BIT, THEN WAIT FOR THE SN MODULE TO TURN OFF THE DONE/ERROR BIT
BEFORE ANOTHER BTR TO THE SAME M–FILE LOCATION CAN BE INITIATED. THIS IS ONE
COMPLETE BTR CYCLE.
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| VIRTUAL
| BTR DONE
| BIT
| B3
|–+––––]/[–––––+–––––––––––––––––––––––––––––––––––––––––––––––––––––––(U)–––––|
| | 13 |
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| | VIRTUAL |
| | BTR ERROR |
| | BIT |
| | B3 |
| +––––]/[–––––+
| 12

Directional Non Continuous Block Transfer Example

The following rungs demonstrate a directional non-continuous block
transfer. The block transfer executes once for every false-to-true
transition of the input. Please note that the input bit I:2.0/0 was
chosen randomly for this example and can be any address in your
program used to initiate a BTR. Also note that this same method
may be used for a BTW.
RIO Block Transfer
BTR
CONTROL
+COP–––––––––––––––+ |
+–|
|Source #B3:100| |
|Dest #M0:1.100| |
|Length 3| |
+––––––––––––––––––+ |
BTR STATUS
+COP–––––––––––––––+ |
+–|
|Source #M1:1.100| |
|Dest #B3:0| |
|Length 4| |
+––––––––––––––––––+ |
CHECK BTR
STATUS
B3
81
Publication 1747 6.6 - July 1996
5–35
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