В полной доке на 3450 есть раздел "Handheld Data Format Requirements", его стОит почитать целиком.
В частности, там сказано и про Code128:
Код:
Code 128
• Prefix must be an ASCII character '#'.
• Label length excluding prefix character or function code 3 for Code 128
programming labels must meet requirements imposed by the main scan-
ner's fixed or variable label length control for this symbology type.
• Function characters may be transmitted as a hexadecimal value 8x. Where
x correlates to function characters 1 thru 4 as follows:
• x80 = function code 1
• x81 = function code 2
• x82 = function code 3
• x83 = function code 4
• For Code 128 programming labels the format is of the general form '#/
82nnnnn/r ' - /82 is hexadecimal 82 and /r is carriage return.
• Example: '#Code_128.Test'.