Rockwell Automation 1747-DSN DISTRIBUTED I/O SCANNER - Manual (Page 21)

Chapter 3
Configuration and Programming
3–3
The SLC processor input and output images for the scanner are dependent
upon whether the 7 I/O block or 30 I/O block configuration is selected.
7 I/O Block Configuration Input Image
The 7 I/O block configuration input image consists of eight words (one
communication status word and seven input words). Each input word
corresponds to an I/O block address. For example, the input data for I/O
block 7 is located in input word 7. In addition, the bits of each input word
correspond to the inputs on the I/O block. For example,
•
For I/O blocks with 8 inputs, bits 0 – 7 are valid.
•
For I/O blocks with 10 inputs, bits 0 – 9 are valid.
Communication Status (Word 0) – these bits reflect the communication
status of each I/O block.
•
Bit 0 is reserved
•
Bits 1 through 7 provide individual communications status for each
respective I/O block. When communications to an I/O block is lost, the
bit corresponding to the I/O block will be 0. Upon start up, these bits will
be 0 until communications has been established with each I/O block.
•
Bits 8 through 15 always equal 0.
7 I/O Block Configuration Input Image Example
Input File
I/O block Communication Status, Word 0 I:e.0
I:e.1
I:e.6
I:e.7
I/O block 1 Input, Word 1
I/O block 6 Input, Word 6
I/O block 7 Input, Word 7
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Bit Number (decimal)
e = slot number of the SLC rack containing the scanner
Bits 8 – 15 always
equal 0
Bits 8 and 9 are only
available to I/O
blocks
with 10 inputs
Bits 1 – 7, I/O block
communication Status
for I/O blocks 1 – 7
0 = Offline
Reserved
The input word for each I/O block is placed in the word corresponding to the I/O block
address. The bits of each input word correspond to the inputs on the I/O block. For example,
input 5 of I/O block 7 is located in bit 5 of input word 7.
SLC Processor Input and
Output Images