Rockwell-automation 1771-IJ_IK IK ENCODER/COUNTER MODULES Manual de usuario descargar pdf (Pagina 49)

6–5Block Transfer Programming

Publication 1771ĆUM006B-EN-P - June 2002

Note that there is no identifying bit pattern to distinguish preset

words #1 and #2 from each other. The encoder/counter module

identifies these words by their order of transmission in block

transfer. As these words are stored in memory, preset word #1 is

stored in the word immediately following the output control word.

Preset word #2 is then stored in the word immediately following

preset word #1.

The module communicates with any Allen-Bradley processor that

has block transfer capability. The module is a bidirectional block

transfer module. Bidirectional means that the module performs both

read and write block transfer operations. You transfer data from

your module to the processor’s data table with a block transfer read

(BTR) instruction. You transfer data to your module from the

processor’s data table with a block transfer write (BTW) instruction.

PLCĆ2 Family Processors

The following examples use block transfer instructions to perform

block transfers. However, the Mini-PLC-2 (cat. no. 1772-LN3) and

PLC-2/20 (cat. no. 1772-LP1,-LP2) processors use multiple GET

instructions to perform block transfers. Refer to the processor user’s

manual for an explanation of multiple GET block transfer.

The generalized and example programs (Figure 6.3 and Figure 6.4)

demonstrate the use of a single block transfer read (BTR) and a

single block transfer write (BTW) to pass data between the processor

and the module.

Figure 6.3

Generalized Ladder Logic for PLCĆ2 Block Transfer

BTW

File AAA-BBB

BTR

File CCC-DDD

FFM

File CCC-DDD

File EEE-FFF

BTR

1 = source

2 = destination

15962

Example Block Transfer

Programs

1 2 ... 44 45 46 47 48 49 50 51 52 53 54 ... 67 68

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Rockwell-automation 1771-IJ_IK IK ENCODER/COUNTER MODULES Manual de usuario Pagina 49