Rockwell Automation 1771-IL/B , D17716.5.91 ISOLATED ANALOG INPUT Module - Manual (Page 60)

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
1 2 0
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
Number of Words
Binary Bit Pattern
Lower Output Image Table Byte
toTransfer
05 04 03 02 01 00
Default 0 0 0 0 0 0
1 0 0 0 0 0 1
2 0 0 0 0 1 0
3 0 0 0 0 1 1
4 0 0 0 1 0 0
5 0 0 0 1 0 1
6 0 0 0 1 1 0
: :
18 0 1 0 0 1 0
19 0 1 0 0 1 1
Setting the Block Length
(Multiple GET Instructions
only)