Digi XBee 3 Cellular LTE-M User Manual page 72

Examples: IOT protocols with transparent mode
Description
byte 1 Length MSB (0)
byte 2 Length LSB (4)
byte 3 (M)
byte 4 (Q)
byte 5 (T)
byte 6 (T)
Protocol level
byte 7 Level (4)
Connect flags
CONNECT flags byte, see the table below for the bits.
byte 8
Keep alive
byte 9 Keep Alive MSB (0)
byte 10 Keep Alive LSB (60)
Client ID
byte 11 Length MSB (0)
byte 12 Length LSB (4)
byte 13 (D)
byte 14 (I)
byte 15 (G)
byte 16 (I)
The following table describes the fields in the packet:
Field name
Protocol Name
Protocol Level
Connect Flags
Keep Alive
Digi XBee® 3 Cellular LTE-M/NB-IoT Global Smart Modem User Guide
Description
The connect packet starts with the protocol name, which is MQTT. The length of
the protocol name (in bytes) is immediately before the name itself.
Refers to the version of MQTT in use, in this case a value of 4 indicates MQTT
version 3.1.1.
Indicate certain aspects of the packet. For simplicity, this example only sets the
Clean Session flag, which indicates to the client and broker to discard any
previous session and start a new one.
How often the client pings the broker to keep the connection alive; in this
example it is set to 60 seconds.
Get started with MQTT
Hex value
0x00
0x04
0x4D
0x51
0x54
0x54
0x04
0x02
0x00
0x3C
0x00
0x04
0x44
0x49
0x47
0x49
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