Pitney Bowes FastPac DI900 Manuallines page 62

3 • Barcode Theory
First
Barcode
Example
3-10
Representing EOC on the Bit Level for Barcode
Let's make the barcode for the sample application described at the beginning
of this section. Let's start by looking at Byte 1, which looks like this:
BYTE 1
(representing
number "2")
Most Significant Bit (LSB) Least Significant Bit (LSB)
The byte is made up of individual 1's and 0's and these are called bits. For the
DI900/DI950, we number them from right (which is the Least Significant Bit, or
LSB for short) bit 0 to left (which is the Most Significant Bit, or MSB for short)
bit 4.
We can use these bits in the same way that we use OMR marks to flag ac-
tions that we wish to perform. By changing a single bit that appears in the bar-
code, we can perform our EOC control.
So we could say for an EOC present control:
EOC No EOC
00001 00000
OMR
SAF EOC
I I
EOC is set.
BCR
*2*
EOC is set
*Remember that the asterisks are like the SAF and BM
Bitwise breakdown of barcode
2= 00010 The second bit in from the right is interpreted as the EOC mark.
So far we have only identified the EOC bit and the other bits are not set to any
function.
? ? ?
0 0 0
00010
bit 4 3 2 1 0
BM
I
EOC ?
1 0
SV61314 Rev. A