Appendix G – Bar Code Details 
Class Series 2 Programmer’s Manual  205
This printer supports the Code 128 subsets A, B, and C. The printer can be selected to 
start on any code subset and switch to another within the data stream. The default code 
subset is B; otherwise, the first character (A, B, C) of the data field determines the 
subset. Subset switching is only performed in response to code switch command. These 
commands are placed in the data to be encoded at appropriate locations; see Table G-1.  
 
 
The use a B as the first character is recommended to prevent an A or C from changing 
the subset.   
 
 
Subset A: Includes all of the standard uppercase alphanumeric keyboard characters 
plus the control and special characters. To select Code 128 Subset A, place an ASCII A 
(DEC 65, HEX 41) before the data to be encoded. 
 
Subset B: Includes all of the standard uppercase alphanumeric keyboard characters 
plus the lowercase alphabetic and special characters. To select Code 128 Subset B, place 
an ASCII B (DEC 66, HEX 42) before the data to be encoded. If no start character is sent 
for the Code 128 font, Code 128 Subset B will be selected by default. 
 
Subset C: Includes the set of 100 digit pairs from 00 through 99 inclusive, as well as 
special characters. Code 128 Subset C is used for double density encoding of numeric 
data. To select Code 128 Subset C, place an ASCII C (DEC 67, HEX 43) before the data 
to be encoded. Subset C can only encode an even number of numeric characters. When 
the data to be encoded includes an odd number of numeric characters, the last character 
causes the printer to automatically generate a “switch to subset B” and encode the last 
character appropriately in subset B. 
 
Special Character Handling: Characters with an ASCII value greater than 95 are 
considered special characters. To access these values, a two-character reference table is 
built into the printer (see below).  
 
For example, to encode FNC2 into a Code 128 Subset A bar code, send the ASCII “&” 
(DEC 38, HEX 26) followed by the ASCII “B” (DEC 66, HEX 41).  
 
Sample: ATEST&B123   Encoded: TEST<FNC2>123 
 
 
 
 
ASCII  2 CHAR  CODE A  CODE B  CODE C 
96 &A FNC3 FNC3 -NA- 
97  &B  FNC2  FNC2  -NA- 
98 &C SHIFT SHIFT -NA- 
99  &D  CODEC  CODEC  -NA- 
100 &E CODEB FNC4 CODEB 
101  &F  FNC4  CODEA  CODEA 
102 &G FNC1 FNC1 FNC1 
 
Table G-1: Special Character Handling