Directional 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
WHEN THE ERROR OR DONE BIT IS SET INDICATING THAT THE BTR COMPLETED EITHER
UNSUCCESSFULLY OR SUCCESSFULLY, THE ENABLE BIT MUST BE UNLATCHED BY THE LADDER
PROGRAM. THE 1747–SN SCANNER THEN UNLATCHES THE ERROR/DONE BIT TO COMPLETE THE
BLOCK TRANSFER HAND–SHAKE PROCESS. AT THIS TIME THE "CHECK BTR STATUS" BIT
MUST BE UNLATCHED TO AVOID UNNECESSARY M–FILE ACCESSES.
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| VIRTUAL
| BTR DONE
| BIT
| B3
|–+––––]/[–––––+–––––––––––––––––––––––––––––––––––––––––––––––––––––––(U)–––––|
| | 13 |
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| | VIRTUAL |
| | BT ERROR |
| | BIT |
| | B3 |
| +––––]/[–––––+
| 12

Directional Continuous Block Transfer Example

The following rungs demonstrate a directional continuous block
transfer. As long as the BTR precondition bit is true, block transfer
reads execute continuously. Use the same method 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
5–29
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