Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE - Manual (Page 65)

Choosing Module Features
Chapter 3
3Ć23
inserts a space (20 hex) for one ASCII or two ASCII characters per word
conversion, or it inserts a zero (00 hex) for BCD and hex data conversion.
The module also adds a fill character to justified BCD data. The fill
character that it inserts is a zero for each missing digit. The module also
inserts zeros leading a BCD number, if necessary, to align the BCD
number on a word boundary (right justified).
Some ASCII devices, such as bar code readers, generate a series of
characters that precede and/or trail data characters. Often, some or all of
these leading or trailing characters contain no information of use to the PC
processor. If your ASCII device generates header and/or trailing
characters that are not used, you can remove them. You can remove up to
15 characters of either type (Figure 2.10). If you do not want to remove
any, set the corresponding bits to zero.
Figure 2.10
Removing Header and Trailing Characters
Header
Characters
Data Characters
Data String
Trailing
Characters
Remove up to 15 header and/or trailing characters
11829
Record the number of trailing characters in IW4(04-07) and the number of
header characters in IW4(00-03) that you want to remove. Write the
binary code for the numbers on the form (found at the end of this chapter)
or in the boxes below.
IW4
Removed
07 06 05 04 03 02 01 00
Removed
Trailing
Characters
Trailing
Characters
Removing Header and Trailing
Characters, IW4(00Ć03, 04Ć07)