Ascension laserBIRD, Installation And Operation Manual

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4: Software Operation: Tools for Successful Tracking
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bit (Marks with "1" if first byte)
MS BIT LS BIT
7 6 5 4 3 2 1 0 WORD #
1 1 0 0 1 0 0 0 #1 LSByte
0 0 0 0 1 0 0 0 #1 MSByte
0 1 0 1 0 0 0 1 #2 LSByte
0 0 0 1 1 0 0 1 #2 MSByte
0 1 0 1 1 0 0 1 #3 LSByte
0 0 1 0 1 0 1 0 #3 MSByte
The user's computer can identify the beginning of the data record by catching the leading "1", and
converting subsequent data bytes back to their proper binary values.
HOST:
1) Receives data bytes in stream after
2) Shifts each LSByte left one bit
catching first marked "1" (Changes
that "1" back to a "0")
01001000 LS 10010000 LS
00001000 MS 00001000 MS
01010001 LS 10100010 LS
00011001 MS 00011001 MS
01011001 LS 10110010 LS
00101010 MS 00101010 MS
3) Combines each MSByte/LSByte pair
4) Shifts each word left one more
into data words bit, giving the correct original
binary value
MS LS MS LS
00001000 10010000 00010001 00100000
00011001 10100010 00110011 01000100
00101010 10110010 01010101 01100100
You don't need to worry about the fact that the two least significant bits are different because the
data words do not use these bits.
RS232 Command Reference
All commands are listed alphabetically in the following section. Each command description
contains the command codes required to initiate the commands, as well as the format and scaling
of the data records which The Bird will output to the host computer.