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Motus Reference Manual
Page 103 of 146
Version 1.1
29/11/2019
16.5 Packet Rates
The packet rates can be configured either using Motus Manager or through the
Packets Period Packet. By default Motus is configured to output the System State
Packet at 50Hz. When configuring packet rates it is essential to ensure the baud rate is
capable of handling the data throughput. This can be calculated using the rate and
packet size. The packet size is the packet length add five to account for the packet
overhead. For example to output the system state packet at 50Hz the calculation
would be:
Data throughput = (100 (packet length) + 5 (fixed packet overhead)) * 50 (rate)
Data throughput = 5250 bytes per second
Minimum baud rate = data throughput x 11 = 57750 Baud
Closest standard baud rate = 115200 Baud
When multiple packets are set to output at the same rate, the order the packets
output is from lowest ID to highest ID.
16.6 Packet Timing
Packets are output in order of packet ID from lowest ID to highest ID and all packets
that are output in one sequence have their data matched to the same time of validity.
The time of validity can be found in either the System State Packet, the Unix Time
Packet or the Formatted Time Packet. For example if the Unix Time Packet, Status
Packet and NED Velocity Packet packet were all set to output at 10 Hz, at each 0.1
second period the three packets would output consecutively by order of packet ID with
all data synchronised between them and the Unix Time Packet providing the time of
validity for the other two packets.
16.7 Packet Summary
Packet ID Length R/W Name
System Packets
0 4 R Acknowledge Packet
1 - W Request Packet
2 1 R/W Boot Mode Packet
3 24 R Device Information Packet
4 4 W Restore Factory Settings Packet
5 4 W Reset Packet
10 - R/W Serial Port Pass-through Packet
State Packets
20 100 R System State Packet
21 8 R Unix Time Packet
22 14 R Formatted Time Packet