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dd
is the least significant octet of the data payload for 32-bit payload (polling).
XX
is the message
checksum
, the exclusive-OR of all of the octets from the address
through the data bytes, inclusive.
>
is the
end
of message character, a close angle bracket character, an ASCII
3𝐸
ℎ𝑒𝑥
.
The registers are:
00 Magic Number
should be
𝐶𝐴𝐹𝐸
ℎ𝑒𝑥
. Used internally to initialize and verify the
EEPROM.
01 Mode
00= net only, 01=fps, 02=m/s, 03=msec
02 Net Address
01 to FE
03 LCD Contrast
Usually near 32(
20
ℎ𝑒𝑥
).
04 Trip Level
The input trip level in units of 26.85 millivolts.
05 Dead Time
The input dead time for debouncing, in units of 27.1 nanoseconds.
06 Distance
The spacing of the light curtains in units of 0.001 inches.
The following is an example of polling unit 2 after an event.
The master sends:
<0204000000000006>
The slave responds:
<0004100989680xx>
<00043009959D0xx>
<00043009A9250xx>
<00041009B7CB0xx>
<0004000000000xx>
This is interpreted as follows:
The first message is returned to the master (00), a poll response (04), for sensor 1 (1), a lead
edge (0), at time 00989680, with checksum xx. The time is a decimal encoding of the item in
units of 100 nanoseconds, so this 1.0000000 seconds from the time synchronization.
Содержание VelociGraph VG03
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