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Dual port Layout
Adapter Status Table
Allen-Bradley Parts
Programming Overview
To write effective programs, you must understand the:
dual-port layout
adapter status table
I/O image tables
You must also be familiar with the command interface and know how to
handle host interrupts.
The dual-port RAM of the KTx is used for communication between the
host and the 1784-KTx scanner. Briefly, the dual port is divided as follows.
DP offset
Memory area
:000h 017h
Dual port common area
:018h 07bh
Reserved
:07ch 07fh
Misc scanner variables
:080h 1ffh
Adapter status table
:200h 2ffh
Command buffer
:300h 3ffh
Confirmation buffer
:400h 5ffh
Input image table
:600h 7ffh
Output image table
A complete listing is found in appendix A.
For each of the 128 possible adapter addresses, there are 3 contiguous
bytes of data in the dual port:
adapter configuration byte
adapter fault byte
adapter retry count byte
Chapter 6 defines the contents of the status bytes and tells you how to
address status bytes.
Chapter
3
3-1
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