Rockwell Automation 1771-IJ_IK IK ENCODER/COUNTER MODULES - Manual (Page 50)

6–6 Block Transfer Programming
Publication 1771ĆUM006B-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 PLCĆ2 Block Transfer
010
EN
16
110
DN
16
010
EN
17
110
DN
17
0053
EN
17
0053
DN
15
110
17
1
2
15963
BLOCK XFER WRITE
DATA ADDR:
MODULE ADDR:
BLOCK LENGTH:
FILE:
0050
101
0
0200 - 0277
FILE TO FILE MOVE
COUNTER ADDR:
POSITION:
FILE LENGTH:
FILE A:
0053
001
001
0203 - 0203
FILE R:
RATE PER SCAN 0204 - 0204
001
BLOCK XFER READ
DATA ADDR:
MODULE ADDR:
BLOCK LENGTH:
FILE:
0051
101
0
0203 - 0302
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.