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6–6
Block Transfer Programming
Publication 1771 UM006B-EN-P - June 2002
Rung Descriptions
Rungs 1 and 2 - These rungs request the block transfer write (BTW)
and block transfer read (BTR) operations.
Rung 3 - When the processor successfully completes a BTR
operation, it sets the done (DN) bit and enables the file-to-file move
(FFM) instruction. The FFM instruction moves the BTR data file
(CCC-DDD) into a storage data file (EEE-FFF). This prevents the
processor from using invalid data if a block transfer communications
fault should occur.
Figure 6.4
Example Ladder Logic for PLC 2 Block Transfer
1
2
110
17
For PLC-2 family processors, we recommend that you set the block
length to zero. Then the module determines the number of transfer
words. The 1771-IJ/IK defaults to 3 words in a BTW and 1 word in
a BTR if you program a block length of zero.
BLOCK XFER WRITE
DATA ADDR:
0050
MODULE ADDR:
101
BLOCK LENGTH:
FILE:
0200 - 0277
BLOCK XFER READ
DATA ADDR:
0051
MODULE ADDR:
101
BLOCK LENGTH:
FILE:
0203 - 0302
FILE TO FILE MOVE
COUNTER ADDR:
0053
POSITION:
001
FILE LENGTH:
001
FILE A:
0203 - 0203
FILE R:
0204 - 0204
RATE PER SCAN
001
010
EN
16
110
DN
0
16
010
EN
17
110
DN
0
17
0053
EN
17
0053
DN
15
15963
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