Code 128
Specification
A Code 128 barcode will have six sections:
Quiet Zone
Start Character
Encoded Data
Check Character
Stop Character
Quiet Zone
The check character is calculated from a weighted sum (modulo 103) of all the characters.
Subtypes
Code 128 actually includes 107 symbols: 103 data symbols, 3 start codes, and 1 stop code. To represent all 128 ASCII values, there are actually three subcodes, which can be mixed within a single barcode:
128A – ASCII characters 00 to 95 (0-9, A-Z and control codes) and special characters
128B – ASCII characters 32 to 127 (0-9, A-Z, a-z) and special characters
128C – 00-99 (double density encoding of numeric only data) and FNC1
Quiet Zone
The quiet zone should be at least ten times the width of the narrowest bar/space element.
Start/Stop and Encoded Data
Each character in the barcode symbol is composed of three bars and three spaces. (The stop adds an additional extra bar of length 2.) Each bar or space is 1, 2, 3 or 4 units wide, the sum of the widths of bars must be even, the sum of the widths of the spaces must be odd, and total 11 units per character. For instance, encoding the ASCII value 0 can be viewed as 10011101100, where a 1 is a bar and a 0 is a space. A combination which contains a single 1 would be the thinnest line in the bar code. A combination including three 1 (111) in sequence indicates a bar three times as thick as a single 1 bar. More information is available at Barcode Island.
Check Digit Calculation
The check digit is a Modulo 103 checksum. It is calculated by summing the start code ‘value’ to the products of each character’s ‘value’ multiplied by its position in the barcode string. The left most character is position 1. The sum of the start code value and the products is divided by 103. The remainder is the check digit’s ‘value’.
Calculating Check Digit With Multiple Variants
As Code 128 allows multiple variants, as well as switching between variants within a single barcode, it is important to remember that the absolute Code 128 value of a character is completely independent of its value within a given variant. For instance the Variant C value “33” and the Variant B value “A” are both considered to be a Code 128 value of 33, and the check digit would be computed based on the value of 33 times the character’s position within the barcode. A complete table of Variant B and C values, as well as algorithmic conversion between Code 128 values and ASCII values, is available here.
Bar Code Widths
Code128 specifies a combination of 6 bars and spaces for each character except the Stop character, which uses 7. Thus, each character begins with a bar and ends with a space (with the exception of the stop character, which ends in a bar). The following tables detail the widths associated with each bar and space for each character. The width of each bar or space can be 1, 2, 3 or 4 units. Using the example above, an ‘A’ would be depicted as 10100011000, or as 111323 in the tables below.
Code 128
Value
Bar/Space Weights
128A
128B
128C
0
212222
space
space
00
1
222122
!
!
01
2
222221
”
”
02
3
121223
#
#
03
4
121322
$
$
04
5
131222
%
%
05
6
122213
&
&
06
7
122312
‘
‘
07
8
132212
(
(
08
9
221213
)
)
09
10
221312
*
*
10
11
231212
+
+
11
12
112232
,
,
12
13
122132
–
–
13
14
122231
.
.
14
15
113222
/
/
15
16
123122
0
0
16
17
123221
1
1
17
18
223211
2
2
18
19
221132
3
3
19
20
221231
4
4
20
21
213212
5
5
21
22
223112
6
6
22
23
312131
7
7
23
24
311222
8
8
24
25
321122
9
9
25
26
321221
:
:
26
27
312212
;
;
27
28
322112
<
<
28
29
322211
=
=
29
30
212123
>
>
30
31
212321
?
?
31
32
232121
@
@
32
33
111323
A
A
33
34
131123
B
B
34
35
131321
C
C
35
36
112313
D
D
36
37
132113
E
E
37
38
132311
F
F
38
39
211313
G
G
39
40
231113
H
H
40
41
231311
I
I
41
42
112133
J
J
42
43
112331
K
K
43
44
132131
L
L
44
45
113123
M
M
45
46
113321
N
N
46
47
133121
O
O
47
48
313121
P
P
48
49
211331
Q
Q
49
50
231131
R
R
50
51
213113
S
S
51
52
213311
T
T
52
53
213131
U
U
53
54
311123
V
V
54
55
311321
W
W
55
56
331121
X
X
56
57
312113
Y
Y
57
58
312311
Z
Z
58
59
332111
[
[
59
60
314111
60
61
221411
]
]
61
62
431111
^
^
62
63
111224
_
_
63
64
111422
NUL
`
64
65
121124
SOH
a
65
66
121421
STX
b
66
67
141122
ETX
c
67
68
141221
EOT
d
68
69
112214
ENQ
e
69
70
112412
ACK
f
70
71
122114
BEL
g
71
72
122411
BS
h
72
73
142112
HT
i
73
74
142211
LF
j
74
75
241211
VT
k
75
76
221114
FF
l
76
77
413111
CR
m
77
78
241112
SO
n
78
79
134111
SI
o
79
80
111242
DLE
p
80
81
121142
DC1
q
81
82
121241
DC2
r
82
83
114212
DC3
s
83
84
124112
DC4
t
84
85
124211
NAK
u
85
86
411212
SYN
v
86
87
421112
ETB
w
87
88
421211
CAN
x
88
89
212141
EM
y
89
90
214121
SUB
z
90
91
412121
ESC
{
91
92
111143
FS
|
92
93
111341
GS
}
93
94
131141
RS
~
94
95
114113
US
DEL
95
96
114311
FNC 3
FNC 3
96
97
411113
FNC 2
FNC 2
97
98
411311
Shift B
Shift A
98
99
113141
Code C
Code C
99
100
114131
Code B
FNC4
Code B
101
311141
FNC 4
Code A
Code A
102
411131
FNC 1
FNC 1
FNC 1
103
211412
Start Code A
104
211214
Start Code B
105
211232
Start Code C
106
2331112
Stop
The “Code A”, “Code B” and “Code C” symbols cause all future symbols to be interpreted according to the corresponding subcode. The “Shift” symbol switches a single following symbol’s interpretation between subcodes A and B.
The FNCx codes are used for special purposes. FNC1 at the beginning of a bar code indicates that it begins with a 2- 3- or 4-digit application identifier assigned by the Uniform Code Council, which explains the following digits. For example, application identifier 421 indicates that an ISO 3166-1 numeric country code and ship-to postal code follows. For example, the U.S. ZIP code for the White House would generally be printed as “(421) 840 20500”, but would actually be coded as “[Start C] [FNC1] 42 18 40 20 50 [Code A] 0 [Check symbol 80] [Stop]”
Availability
For the end user, Code 128 barcodes may be generated by either an outside application to create an image of the barcode, or by a font based barcode solution. Either solution requires the use of an application or an application add in to calculate the check digit and create the barcode.
External links
Download Open-Source Barcode Generator for Code 128 (C++, VB, Excel Macros, etc.)
Used barcode scanner
Free Barcode Online Generator This free utility supports creating a variety of barcode formats including Code 128 and UCC/EAN-128.
Sample code
Python Bar Code 128 This code appears to draw boxes 1 pixel wide. It appears it was modified from a short line long line bar code which would have drawn lines. The “Black boxes” should be the same size as the “White Boxes”.
GenCode128 Free C# source code implementation of Code128. Almost all features are implemented, but is not 100% complete.
Barcode Image Generation Library Free C# barcode generation library implementation supporting many barcode symbologies including Code128.
Barcode::Code128 Free Perl barcode generation module.
GOCR Free OCR with Code 128 recognition.
Barcode Code 128 Free JavaScript source code implementation of Code128.
v d e
Barcodes
Linear Barcodes
Code 39 – Code 93 – Code 128 – Codabar – European Article Number – ITF-14 – MSI Barcode – Plessey – UPC
UPC-A
MaxiCode
Post Office Barcodes
CPC Binary Barcode – Facing Identification Mark – PostBar – POSTNET – RM4SCC – Intelligent Mail Barcode – PLANET
2D Barcodes (Stacked)
PDF417
2D Barcodes (Matrix)
Aztec Code – Data matrix – EZcode – MaxiCode – QR Code
Polar Coordinate Barcodes
MaxiCode – ShotCode
Next Generation
High Capacity Color Barcode (Microsoft Tag) – Sony Dynamic Digital Sound
Technological issues
Barcode scanner – Barcode printer
Other data tags
RFID – Bokode
Related topics
Supply Chain Management – Object hyperlinking – Mobile tagging
Categories: BarcodesHidden categories: All articles with unsourced statements | Articles with unsourced statements from May 2009
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