Rockwell Automation 1771-IFE , D17716.5.90 USER MNL. ANALOG INPUT Module User Manual

Page 57

Appendix D

Block Transfer (Mini-PLC-2 and

PLC-2/20 Processors)

D-3

The input module transfers a specific number of words in one block length.
The number of words transferred is determined by the block length entered
in the output image table control byte corresponding to the module’s
address.

The bits in the output image table control byte (bits 00 - 05) must be
programmed to specify a binary value equal to the number of words to be
transferred.

For example, Figure D.2 shows if your input module is set up to transfer 6
words, you would set bits 01 and 02 of the lower image table control byte.
The binary equivalent of 6 words is 000110. You would also set bit 07
when programming the module for block transfer read operations. Bit 06 is
used when block transfer write operations are required.

Figure D.2

Setting Block Length (Multiple GET Instructions only)

1 0 0 0 0 1 1 0

Data Address

Contains Module

Address in BCD

Output Image Table Control

Byte Contains Read

Enable Bit and Block

Length in Binary Code

010

012

017

027
030

Data Table

1
R

Control

Byte

Read 6 Words

from Module

Block Transfer

Read Enable Bit

For Block

Transfer Active

Operations Only

Output Image Table

12172

Number of

Words to

Binary Bit Pattern

Lower Output Image Table Byte

Words to

Transfer

Default

: :

Setting the Block Length

(Multiple GET Instructions

only)