Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE - Manual (Page 142)

Function of Control/Status Bits
Chapter 6
6Ć7
The default string length of the module is 10 characters in data mode, 124
characters in report generation mode. The maximum string length that the
module can accept is 62 characters in data mode and 999 characters in
report generation mode.
When the module detects that you set the string length greater than 62
characters in data mode, it faults due to an initialization error. The
module disables its interface port and sets bit SW1(12).
Bits: IW2(14-16)
Function:Type of Data Conversion
Description: When operating in data mode, select any one of five types
of data conversion to match your ASCII device, or to match your
requirements for manipulating data.
16 15 14 Data Conversion
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
2 ASCII characters/word
3 BCD characters/word
4 BCD characters/word
1 ASCII character/word
4 HEX characters/word
all
other
Invalid
The type of data conversion refers to the manner in which data is
converted by the module and stored in the processor data table. You can
change from one type of data conversion to another only by re-initializing
the module.
When operating in report generation mode, you must select either 3 BCD
or 4 BCD characters per word for storing BCD numbers. The module
automatically selects 2 ASCII characters per word for non-BCD data.
Your choice of 3 BCD or 4 BCD characters per word depends on your
requirements for manipulating data and/or on the characteristics of your
ASCII device.
When the module detects an invalid setting for data conversion, it faults
due to an initialization error. Refer to Fill Character Bit, IW4(10-16), and
“Your ASCII Module Inserts Fill Characters,” P. 2-22.