CODE 128 INTRODUCTION
Code 128 is a alphanumeric symbology. Code 128 symbology must include a checksum digit. Code 128 has three character Set: A,B,C. Three different start characters tell the reader the character set used in the following encoding, and three shift codes permits changing character set inside the symbol. From the table below, we can see that character set A and B is used to encode alpha-numeric information while character set C offers double density when being used to encode numeric data. The special character Shift, changes the character set of the immediately followed character. The shift work only with Code A or Code B characters. Four FNC characters are listed, FNC2 is used to tell barcode reader to store the data and transmit with next symbol; FNC1, FNC3 and FNC4 are reserved for future applications. Encoding Table as follow:
|
VALUE
|
CHARACTER SET
|
VALUE
|
CHARACTER SET |
|||||
|
A
|
B
|
C
|
A
|
B
|
C
|
|||
|
00
|
SP
|
SP
|
00
|
53
|
U
|
U
|
53
|
|
|
01
|
!
|
!
|
01
|
54
|
V
|
V
|
54
|
|
|
02
|
“
|
“
|
02
|
55
|
W
|
W
|
55
|
|
|
03
|
#
|
#
|
03
|
56
|
X
|
X
|
56
|
|
|
04
|
$
|
$
|
04
|
57
|
Y
|
Y
|
57
|
|
|
05
|
%
|
%
|
05
|
58
|
Z
|
Z
|
58
|
|
|
06
|
&
|
&
|
06
|
59
|
[
|
[
|
59
|
|
|
07
|
‘
|
‘
|
07
|
60
|
\
|
\
|
60
|
|
|
08
|
(
|
(
|
08
|
61
|
]
|
]
|
61
|
|
|
09
|
)
|
)
|
09
|
62
|
^
|
^
|
62
|
|
|
10
|
*
|
*
|
10
|
63
|
_
|
_
|
63
|
|
|
11
|
+
|
+
|
11
|
64
|
NUL
|
`
|
64
|
|
|
12
|
,
|
,
|
12
|
65
|
SOH
|
a
|
65
|
|
|
13
|
–
|
–
|
13
|
66
|
STX
|
b
|
66
|
|
|
14
|
.
|
.
|
14
|
67
|
ETX
|
c
|
67
|
|
|
15
|
/
|
/
|
15
|
68
|
EOT
|
d
|
68
|
|
|
16
|
0
|
0
|
16
|
69
|
ENQ
|
e
|
69
|
|
|
17
|
1
|
1
|
17
|
70
|
ACK
|
f
|
70
|
|
|
18
|
2
|
2
|
18
|
71
|
BEL
|
g
|
71
|
|
|
19
|
3
|
3
|
19
|
72
|
BS
|
h
|
72
|
|
|
20
|
4
|
4
|
20
|
73
|
HT
|
I
|
73
|
|
|
21
|
5
|
5
|
21
|
74
|
LF
|
j
|
74
|
|
|
22
|
6
|
6
|
22
|
75
|
VT
|
k
|
75
|
|
|
23
|
7
|
7
|
23
|
76
|
FF
|
l
|
76
|
|
|
24
|
8
|
8
|
24
|
77
|
CR
|
m
|
77
|
|
|
25
|
9
|
9
|
25
|
78
|
SO
|
n
|
78
|
|
|
26
|
:
|
:
|
26
|
79
|
SI
|
o
|
79
|
|
|
27
|
;
|
;
|
27
|
80
|
DLE
|
p
|
80
|
|
|
28
|
<
|
<
|
28
|
81
|
DC1
|
q
|
81
|
|
|
29
|
=
|
=
|
29
|
82
|
DC2
|
r
|
82
|
|
|
30
|
>
|
>
|
30
|
83
|
DC3
|
s
|
83
|
|
|
31
|
?
|
?
|
31
|
84
|
DC4
|
t
|
84
|
|
|
32
|
@
|
@
|
32
|
85
|
NAK
|
u
|
85
|
|
|
33
|
A
|
A
|
33
|
86
|
SYN
|
v
|
86
|
|
|
34
|
B
|
B
|
34
|
87
|
ETB
|
w
|
87
|
|
|
35
|
C
|
C
|
35
|
88
|
CAN
|
x
|
88
|
|
|
36
|
D
|
D
|
36
|
89
|
EM
|
y
|
89
|
|
|
37
|
E
|
E
|
37
|
90
|
SUB
|
z
|
90
|
|
|
38
|
F
|
F
|
38
|
91
|
ESC
|
{
|
91
|
|
|
39
|
G
|
G
|
39
|
92
|
FS
|
|
|
92
|
|
|
40
|
H
|
H
|
40
|
93
|
GS
|
}
|
93
|
|
|
41
|
I
|
I
|
41
|
94
|
RS
|
~
|
94
|
|
|
42
|
J
|
J
|
42
|
95
|
US
|
DEL
|
95
|
|
|
43
|
K
|
K
|
43
|
96
|
FNC3
|
FNC3
|
96
|
|
|
44
|
L
|
L
|
44
|
97
|
FNC2
|
FNC2
|
97
|
|
|
45
|
M
|
M
|
45
|
98
|
SHIFT
|
SHIFT
|
98
|
|
|
46
|
N
|
N
|
46
|
99
|
Code C
|
Code C
|
99
|
|
|
47
|
O
|
O
|
47
|
100
|
Code B
|
FNC4
|
Code B
|
|
|
48
|
P
|
P
|
48
|
101
|
FNC4
|
Code A
|
Code A
|
|
|
49
|
Q
|
Q
|
49
|
102
|
FNC1
|
FNC1
|
FNC1
|
|
|
50
|
R
|
R
|
50
|
103
|
START A
|
START A
|
START A
|
|
|
51
|
S
|
S
|
51
|
104
|
START B
|
START B
|
START B
|
|
|
52
|
T
|
T
|
52
|
105
|
START C
|
START C
|
START C
|
|
|
|
STOP
|
STOP
|
STOP
|
|||||
Code 128 checksum digit calculation
The CODE 128 checksum digit is the result of the weighted sum of the values of each of the digits modes 103.
The steps for calculating the check digit are as follows:
- Add the start character value(103, 104, or 105) to the running checksum.
- Take each character in the message, take its value, and multiply it by its character position, and add the total to the running checksum.
- The checksum digit is the result of running checksum modulo 103.
Example: to calculate the checksum digit example :”EASESOFT1234″.
|
String
|
Start B
|
E
|
A
|
S
|
E
|
S
|
O
|
F
|
T
|
Start C
|
12
|
34
|
|
Value
|
104
|
37
|
33
|
51
|
37
|
51
|
47
|
38
|
52
|
99
|
12
|
34
|
|
Weight
|
1
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
|
Sum
|
104
|
37*11=37
|
33*2=66
|
51*3=153
|
37*4=148
|
51*5=255
|
47*6=282
|
38*7=266
|
52*8=416
|
99*9=891
|
12*10=120
|
34*11=374
|
- Summing up the sum of each character, The sum is 104+37+66+153+148+255+268+266+416+891+120+374=3112.
- 3112 divides 103, the remainder is 22,so the checksum digit is 22.
STRUCTURE OF A CODE 128 BARCODE
A Code 128 barcode has the following physical structure:
- Start code, which is the code 103, 104, or 105 from the encoding table .
- Each of the data bytes of the message, encoded with the encoding table.
- The checksum byte, calculated as described above and encoded using the table.
- Stop character.
- Termination bar of 11.
UCC/EAN-128 SYMBOLOGY
UCC/EAN-128 only can encode numeric data using the Code 128 Character Set C. UCC/EAN-128 starts with character C, follow FNC1 character( 102) and other data.