Module/Processor Communication; Chapter Objectives; Block Transfer; Block Transfer Write Data - AB Quality Allen-Bradley 1771-DE User Manual

Chapter Objectives

Block Transfer

Block transfer write Data

Module/Processor Communication

This chapter describes file parameters for the block-transfer data files you
use to write data to and read data from the absolute encoder module.
The absolute encoder module and the processor communicate through
block-transfer programming. Processors that use block-transfer
programming are listed below, along with the respective programming
manual. Refer to the latest edition of the programming manual for a
detailed description of block transfer.
Processor
Mini PLC 2
Mini PLC 2/15
Mini PLC 2/05
PLC 2/20
PLC 2/30
PLC 3
You write data to the module in blocks. You can write 5, 10, 15 or 20
words in one block-transfer operation. Each block of five words is
associated with two outputs and is identical to each other in format:
words 1-5 - outputs 0 and 1
words 6-10 - outputs 2 and 3
words 11-15 - outputs 4 and 5
words 16-20 - outputs 6 and 7
The first word of each block is a control word. The last four words are
preset words. The formats of the write-data words and control word 1 are
shown in Figure 4.1 and are described here.
You can send a maximum of 20 words (four block of five words) in one
block-transfer operation. The number of words you send to the module
determines how many outputs it controls. If you want to change data for
4
Chapter
Programming and Operations
Manual Publication Number
1772 6.8.4
1772 6.8.2
1772 6.8.6
1772 6.8.1
1772 6.8.3
1772 6.4.1
4 1