Difference between LQI in AF_INCOMING_MSG and MGMT_LQI_QUERY.

Given there is a single hop (no repeaters) between devices, why is the LQI in AF_Incoming_MSG different from the MGMT_LQI_RSP? Isn't it supposed to be equal?

It is not equal since each device measures its own LQI using the messages it receives from its neighbors.  This is necessary as each node has its own RSSI and transmits messages at its own dBm level.  Device A receives MGMT_:LQI_RSP, which contains the LQI measured from Device B, but has its own LQI measurement from AF_Incoming_MSG since both devices are independent and capable of transmitting/receiving at different radio levels based on their own hardware.

Regards,
Ryan

But if device A receive a message from device B, isn't supposed the AF_INCOMING_MSG value to be the same value inside the neighborlqilist in the device A to Device B? I don't get why they are different, i get it the different devices have different LQI measurement but aren't the LQI, for the same device, supposed to be equal?

Have you saved the values of the local device A neighborlqilist to compare against the incoming AF_INCOMING_MSG value?  You should not be comparing against the MGMT_LQI_RSP from a neighboring device.  The LQI can change quickly given distance/barriers between devices, network interferers, etc.

Regards,
Ryan

Checked the latest AF_INCOMING_MSG LQI Value with NeighborLQIList

NeighborLQIList of the local device (A) or from the remote device (B)?

Regards,
Ryan

Local Device A

How are you obtaining it, and what is the time difference when compared to the incoming message?  What difference in values is observed?

Regards,
Ryan

I obtain it by sending ZDO_MGMT_LQI.

Time difference: 1 minute

Difference in values: up to +/-50

What are the parameters in the request and the contents of the response?  What is the lqi value from the AF incoming message?

Regards,
Ryan

DstAddr = Local Device A Network Address

StartIndex = 0

Value: 255
AF_INCOMING_MSG Value: 210

ZDO_MGMT_LQI_RES is built with the linkInfo.rxLqi from the neighbor table using an approximation conversion  AF_INCOMING_MSG calculates the macRadioComputeLQI using rssiDbm and a conversion equation.  Thus AF_INCOMING_MSG is more precise for the local device but ZDO_MGMT_LQI_RES is a standard which can be compared against other device values in the network.

Regards,
Ryan

So the difference in values is caused by the different Conversion equation/Aprroximation Conversion?

You can further debug/investigate the application to view the origin of each LQI through the call stack and understand their differences.

Regards,
Ryan