Why connection loss during send command to STM32WB55 MCU on STM32CubeMonitor-RF GUI?

[mnoro.1]

I have a self-design STM32WB board and properly flash "stm32wb5x_FUS_fw.bin", "stm32wb5x_BLE_Stack_full_fw.bin" and "BLE_TransparentMode_reference.hex" STM32_Programmer_CLI.exe. Now I am trying to use STM32CubeMonitor-RF. When I try to connect to it sometimes I receive "Device under test not responding. COM port closed". However, sometime it is connected and after some other actions be disconnected. The ACI Log is as follows:Can anyone help me to resolve this problem?

Thanks.

[Remi QUINTIN]

​ This may happen sometimes when the COM port is not properly released.

In this case, the best to do is to reset your board or even better to completely switch it off and on.

[mnoro.1]

@Remi QUINTIN​  Thanks for your response,

I reset and switch it on and off, but no change seen.

[stephane.legargeant]

In the screenshot, it seems that some command are sent, but there is no reply from the board. Line 52,53,54, the commands is repeated 3 time, but it seems there is no answer for the 1st and 2nd. After few seconds without answer, the software disconnect the port com and displays the pop up.

Could you compare with a Nucleo WB55 ?

[mnoro.1]

@stephane.legargeant​ Thanks for your response,

After commands in lines 52 and 53 I received error "Device under test not responding. COM port closed." Then, when I repeat it in line 54, the board respond command. But disconnect again and I received error again.

Unfortunately, I do not have access to the board at this time.

I also checked my board in STM32CubeProgrammer software. As shown in the image below, I can not read FUS state. Is there a problem with FUS?

[Lep]

I made a board and had the same problem. It was normal to power on several times before, and then I couldn't find the signal. Have you found a solution?