Communication Protocol

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Copyright (c) 2009-2013 RoboPeak Team
Copyright (c) 2013-2019 Shanghai Slamtec Co., Ltd.
Format of the data response packets (Legacy Version)：
RPLIDAR uses the following data response packet structure for responding the
legacy version of EXPRESS_SCAN requests.
Figure 4-11 Format of a RPLIDAR Express Scan Data Response Packet (Legacy
Version)
When working in legacy express scan mode， RPLIDAR will send the above data
packet cyclically to output the measurement data to host system. The packet
contains 16 group of substructures called Cabin in the same format. Each Cabin is
a 5-byte data body with specific structure corresponding with the angle and
distance value of two measurement sampling data sets. Therefore, an express scan
data response packet carries 32 measurement sampling data points.
ChkSum[7:4]
sync1
ChkSum[3:0]
8
3 0
start_angle_q6[7:0]
8
0
start_angle_q6[14:8]
8
0
cabin[0]
40 0
+0
+1
+2
+3
+4
Byte
offset
sync2
8
3 0
S
7
cabin[1]
40
0
+9
cabin[15]
40
0
+79
…
𝑑𝜃

[5:
4
]
8
2
0
+0
+1
+2
+3
distance1[13:6]
8
0
𝑑𝜃

[3:0]
8
0
+4
distance1[5:0]
𝑑𝜃

[5:
4
]
8
2
0
distance2 [13:6]
8
0
distance2[5:0]
𝑑𝜃

[3:0]
4
Cabin