Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE - Manual (Page 138)

Function of Control/Status Bits
Chapter 6
6Ć3
SW(16), before it sends new data. Otherwise, new data could be mixed
with old data or lost.
Bit: CW1(17)
Function: Initialization
Description: Set this bit to tell the module that up to four initialize data
words follow command word one and two. Otherwise, reset it to zero.
Command Word Two, CW2
This word is reserved for future enhancements. Reset it to zero.
Set bits in your initialization words to match the characteristics of your
ASCII module to those of your ASCII device. The bits in the four
initialization words, IW1, IW2, IW3, and IW4, are described below.
You can operate the module in data mode without setting initialization
bits, and without sending initialization data to the module. However, then
the module operates only with default features. Select additional features
by setting initialization bits. To operate in report generation mode, you
must set initialization bits.
Initialization Word One, IW1
Bits: IW1(00-01)
Function: Number of Initialization Words
Description: The setting of bits 00 and 01 tells the module the number of
initialization words you will use to transfer initialization data to the
module.
01 00 Words Used
0
0
1
1
0
1
0
1
word 1
words 1 and 2
words 1, 2, and 3
words 1, 2, 3, and 4
Initialization Words