Laser beta lasermike LS8000-3 - Manual (Page 157)

LaserSpeed 8000-3 Instruction Handbook
RS-232/RS-422 Communication
Part No. 93463 / Drawing No. 0921-01561 Page 157 of 221 Revision A (Sep 2007)
Byte Value
0 FF (hex)
1 FF (hex)
2 FF (hex)
3 FF (hex)
4 FF (hex)
Sy
nc
hr
on
iz
ati
on
5 QF (0-15) can't be FF
6 Length Byte 3 (MSB)
7 Length Byte 2
8 Length Byte 1
9 Length Byte 0 (LSB)
10 Status (0-63)
11 Velocity Byte 3 (MSB)
12 Velocity Byte 2
13 Velocity Byte 1
14 Velocity Byte 0 (LSB)
15 Checksum (8-bit sum of all bytes)
The Length and Velocity values are both 2's complement 32-bit integers that represent the
current length and speed multiplied by 1000. The QF and Status are unsigned bytes. The
Checksum value is the 8-bit sum of all the bytes including the 5 FF's used for
synchronization.
Data Processing Procedure:
1) Wait for 5 sequential FF values
2) If the next value is not FF, store it as the QF, else go to #1
3) Read and store 10 more bytes
4) Check the last byte read (the checksum) to make sure it was correct
5) Process/Store Verified Reading
6) Repeat from step 1