I found there's debug TTL pins on M2U. And I tried CH340 and CP2102 chip to convert serial to USB, but all failed.
I connect M2U <-> chip, GND <-> GND, RX <-> TX, TX <-> RX. And set baud rate to 115200 in Putty or TeraTerm.
With CH340, I got nothing on Putty or TeraTerm.
With CP2102, I can get some readable output from TeraTerm or Putty, but most of them are unreadable codes (see [Picture 1], [Picture 2], [Picture 3]).
Maybe you guys can give me some advice or recommend me some other convert chip.
I brought two new convert board, TL232 and PL2303, don't help.
But I found something interesting. When I connect USB to debug TTL while the board power is disconnected and RJ45 is connected, I can still getting output from COM port, although all the output is unreadable codes.
Maybe the problem isn't the adapter chip.