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How to use
:
WNDSCN
1. Ensure that there are enough data storage registers available in the HP-41C
for the number of bytes (set of eight bars) in the row you will scan under
control. Beginning with R
WNDSCN
register for each byte in a row. A row can be as short as one byte (8 bars), or
as long as 16 bytes (128 bars).
Note: Because the first and the last pairs of bars in a row indicate the scan direction, every row of bar code must also include the
illustrated directional bars.
2. Execute
. The HP-41C will prompt you to scan a row of bar code by displaying
WNDSCN
3. Scan the desired row.
After you scan a row of your bar code, the HP-41C's registers are loaded as follows:
1. The total number of bytes read (n) is placed in the HP-41C's X-register as a
normal digit entry.
2. The decimal equivalent (yyy) of the binary value of each byte is placed
sequentially in the HP-41C's data storage registers. The value of the first
byte is placed in R
01
the value placed in the X-register in step 1, above).
With the decimal form of the byte values in the HP-41C's data storage registers, the
now be accessed and interpreted according to your instructions.
If you execute
in a running program, program execution resumes with the first instruction in program memory following the
WNDSCN
instruction. Note that under
WNDSCN
operations (refer to
appendix
use with
.
WNDSCN
WNDTST
The
wand test function lets you test the wand of any HP-41C bar code by displaying what has been read in a row you
WNDTST
scanned. To use this test, execute
HP-41C's display with the corresponding bar pattern in each consecutive byts of eight bars in a row. The narrow and wide bars
corresponding to 0's and 1's in the display, i.e.,
Note: Because the first and last pairs in a row indicate scan direction, they are not displayed by
HP 82153A - Wand Owner Manual - page 16
,
WNDSCN
01
W: READY
. The value of the last byte is placed in R
control the wand cannot perform the error checking it performs during other wand
WNDSCN
A, Errors and Messages). However, you can design your own error tests in the programs you write for
and scan a row of bar code. Then note and compare each set of digits returned in the
WNDTST
1
1
0
1
uses one data storage
(where n is
n
0
1
0 0 0 0 0 0
Directional Bars
n
R
yyy
01
1
R
yyy
02
2
R
yyy
n
n
operation is complete. The value can
WNDSCN
1
0 0
1
.
WNDTST
Bytes
Total number
of byte in the row.
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