5525B/31/32 Line Matrix Printer Code V Programmer's Reference Manual

Code 128
155
Code 128
Code 128 includes three subsets: A, B, and C. All contain the same bar
patterns, except for the unique start character instructing the bar code reader
which subset is being used. Special characters are available for switching
between the subsets in order to generate the shortest possible bar code.
The Code 128 structure is shown in Figure 11 and described below.
Figure 11. Code 128 Structure
Quiet Zone
Both ends of the bar code structure require blank quiet zones. The quiet
zones should be at least 0.25 inches wide and completely blank to ensure
accurate reading of the start/stop codes and to prevent adjacent bar codes
from overlapping. You are responsible for providing sufficient space on the
form for the quiet zones.
Start/Stop Codes
Code 128 contains special characters which use unique start/stop codes to
identify the leading and trailing end of the bar code. In the automatic mode,
start and stop codes are generated automatically. In the manual mode, you
must supply the start code, but the stop code is generated automatically.
Data Field
Code 128 bar codes support a full ASCII character set: Subset A provides
standard alphanumeric keyboard characters, control and special characters;
subset B includes all standard alphanumeric keyboard characters, lowercase
alphabetical characters, and special characters; subset C provides 100 digit
pairs, from 00 through 99, plus special characters. Table 26 lists the full Code
128 character set.
DATA FIELD
QUIETQUIET START STOP
LOWER GUARD BAND
CODE CODEZONE ZONE
OPTIONAL READABLE DATA FIELD
HEIGHT
STARTING
POSITION
CHECK DIGIT
FIELD
DATA
FIELD
QUIET
ZONE
QUIET
ZONE
STOP
CODE
START
CODE
OPTIONAL
READABLE
DATA
FIELD
HEIGHT
STARTING
POSITION
GUARD
BAND
LOWER
CHECK
DIGIT
FIELD