@dc42 If I send a M408 from the web interface ‘Send’ button during a move without sensing endpoint it responds with the status. If I send it with sensing endpoint it buffers the responses and sends them all at the end of the move. M408 sent using RS232 responds immediately regardless of whether sensing endpoint is on or off. The discrepancies threw me during testing but it doesn’t cause me a problem as I am using the comm port. I'm sorry if I have wasted your time.

M408 does not respond when sensing endstops. What is preventing the response?

@dc42 Thank you for your help.

I am new to the project. I can find the RepRapFirmware versions. How do I identify which is the 2.04 commit of CoreNG? Can you please direct me to older commit.

Thank you for that clarification. I am now getting error:
../src/Platform.cpp:1312:8: error: no match for 'operator!' (operand type is 'SerialCDC')

I am trying to build 2.04. I have tried various branch combinations but keep getting error:
Duet3D\RepRapFirmware\src/RepRapFirmware.h:185:2: error: '__set_BASEPRI_MAX' was not declared in this scope

What are the correct branches to build this version?

Thanks for the information.

Thank you for both replies. M400 will give me what I need though I can see a use for M408. Is there a recommend poll frequency?

I am sending individual commands using the serial port. Is there a way to determine if an axis is moving or has reached its destination?

I have them now. Thank you very much for your help and the explaination.