37
XIII.
APPENDIX
B
DATA TRANSFER FORMAT
When the data transfer interface is implemented, a specific data format is used to
transfer data from the
Pachette 2
to a personal computer. This appendix provides the
necessary information for a programmer to interpret and utilize the data stream sent by
the
Pachette 2
.
The format of the data sent to the personal computer is shown in Figure XIII-A. Each
character in the data stream, represented by “X”, is a 7-bit ASCII encoded decimal
digit (e.g. “1” is encoded as “31” hex, “2” as “32” hex, etc.). The first value
transmitted is a four-digit number representing the velocity used to calculate all
measurements. The second number contains two-digits and it represents the total
number of measurements obtained. The next four-digit number represents the total
average of all measurements (this number is only transmitted in Continuous Avg
mode). Following this will be 1 to N four digit pachymetry measurements, represented
in microns. The number of measurements transferred (N) depends upon the number of
measurements for which the
Pachette 2
was programmed. The data stream is
terminated with ASCII carriage return and line feed characters.
X X X X
X X X X
X X X X
X X
X X X X
CR
ASCII Line Feed
ASCII Carriage Return
Measurement #N
Measurement #1
Total Average
Number of
Measurements (N)
Velocity
LF
...
Figure XIII-A
Format of data stream sent by
Pachette 2
.