Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 84)

Chapter
Programming Block-Transfers 5
5 -10
Asynchronous Block Transfer
You can use this ladder logic program with PLC-5 processors for
asynchronous block transfer. This program assumes that your application
requires a single block- transfer-read (BTR) and block-transfer-write
(BTW) to pass data between the processor and the BASIC module (transfer
of 64 words or less). If transferred data exceeds 64 words you must
program multiple file-to-file moves to move different data sets to and from
block-transfer files.
Rungs 1 and 2 execute the BTR and BTW instructions alternately.
When BTR is completed, BTW enables immediately following BTR scan.
Important: Do not select the continuous mode when using bi-directional
block-transfer. Continuous mode does not allow use of the status bits in
the block-transfer instructions.
BTW
BLOCK XFER WRITE
Rack
Group
Module
0
0
0
N10:10
N10:15
5
Control Block
Data file
Length
File 2,
15
Rung 0
15
Continuous N
N10:10 N11:10
BTR
BLOCK XFER READ
Rack
Group
Module
0
0
0
N11:10
N11:15
5
Control Block
Data file
Length
File 2,
15
Rung 1
15
Continuous N
N10:10 N11:10
File 2, Rung 2
[END OF FILE]
1
2
3
15048
(EN)
(DN)
(ER)
(EN)
(DN)
(ER)
PLC-5

Family Processors
Ladder Logic