How to make a DWM1001 anchor report tags' positioning information?

Hi P.XU,
I am utilizing DWM1001 connected with Raspberry Pi 3+ and have run into the same issue while trying to get data from other tags by using listener mode, specifically the dwm_loc_get function.
The DWM1001 seems to not report what it heard from other around rather than itself while using generic mode probably because it only does exactly what it is commanded from the dwm1001_tlv.h file.
I have tried to simulate the enter command (0x0D) to swtich into shell mode from generic mode by using C function: the proof is that the DWM1001 cannot recognize the command 0x0C (dwm_loc_get). Then I assumed that the command ‘les’ can also be simulated by sending ASCII values owing to the fact that ‘LES’ command is not recognizable in shell mode. However, I just received errors and some data like:

7ea75a80 SPI0: Rx step 1:
SPI0: Wait 10 ms…
SPI: Rx 1 bytes: 0xff
SPI0: Rx step 2:
SPI0: Wait 10 ms…
SPI: Rx 255 bytes: 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
SPI0: Wait 10 ms…
HAL_SPI: ERROR: RET_VAL type wrong: 255

So I would like to ask what I have done wrong in this case and whether I should keep trying to use shell mode by utilizing C function or there is a tlv command that is similar to ‘les’ from shell mode.
Best regards,
Hoa