Rockwell Automation 1747-DSN DISTRIBUTED I/O SCANNER - Manual (Page 24)

Chapter 3
Configuration and Programming
3–6
30 I/O Block Configuration Input Image
The 30 I/O block configuration input image consists of 32 words (two
communication status words and 30 input words). Each input word has a
corresponding I/O block address. For example, the input data for I/O block
31 (there is no I/O block 16) is located in input word 31. 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 Words (words 0 and 16) – these bits reflect the
communication status of each I/O block.
•
Bit 0 of word 0 provides the communication status of all 30 I/O blocks.
When communications with one (or more) I/O block is lost, this bit equals
0. Upon start up, this bit will be 0 until communications has been
established with all configured I/O blocks.
•
Bits 1 through 15 of word 0 provide individual communications status for
the first 15 I/O blocks (words 1 – 15). When communications with an I/O
block is lost, the corresponding bit equals 0. Upon start up, these bits will
be 0 until communications has been established with each corresponding
I/O block.
•
Bit 0 of word 16 is reserved.
•
Bits 1 through 15 of word 16 provide individual communications status
for the remaining 15 I/O blocks (words 17 – 31). When communications
with an I/O block is lost, the corresponding bit equals 0. Upon start up,
these bits will be 0 until communications has been established with each
corresponding I/O block.