Connecting to: /dev/ttyUSB0
Changing monitoring state from "Offline" to "Opening serial port"
Connected to: Serial<id=0x6a972bb0, open=True>(port='/dev/ttyUSB0', baudrate=250000, bytesize=8, parity='N', stopbits=1, timeout=10.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Changing monitoring state from "Opening serial port" to "Connecting"
Send: N0 M110 N0*125
Recv: 1\x95\x961¥\x95%\x01!%¡!\x94\x84\x05\x11\x08
Recv: -¯¡51¡-\x10\xffÔ!çõ\xffÆ\xff-¡1¡!á!1\xff1\xff-0±\xff-0±\xff·\xff·\xff¯¡%õ\x14¤\x08\x94Ñ\x10F\xff±\x10\x08¡õ\x10\x081\xff0\x12nVF\xff¡0\x12\x86V\x08\x84\xff0\x12\x86VF\xff1ú0\x12\x86\x16÷F\xff1ú0\x12\x86\x16÷\x08¡0½R\x08!ú0\x90F\xffñõ°\x80Vç\x86\xff°F\xff\x84\xff°\x02F\xff!Õ\x8e\x10F\xff!Ô°\x10¤\x08ÆÑY
Recv: \x7f\x08Ä\xff°\x00F\xff%\xff\x000±F\xff¡\x00ð\x86V\x08\x04\xff\x000±F\xff1ú\x000±\x10F\xff1ú\x100±\x10\x08¡\x000±¾R\x08!ÕÀ0±\x00F\xff%\xff\x000±\x80F\xff\x86\xff\x000±\x96\x08\x84\xff\x000±\x10F\xffñÔ\x000±\x10¤\x08ÆÑ\x08w\x08Æ\xff\x08\x7f\x08\x96\xff\x12¡õ¯á%õ»¤\x08\x94Ñ\x10F\xff±\x10\x08¡õ\x10\x081\xff0\x12\x86VF\xff¡0\x12\x86V\x08\x84\xff0\x12\x86VF\xff1úð\x000±\x10F\xff1ú0\x12\x86~\x10\x08¡0åF\xff!ú°\xffF\xff!õ°\x80F\xff\x86\xff°F\xff\x84\xff°\x02F\xff!Õ°\x10F\xff!Ô°\x10¤\x08ÆÑ0
That is a typical response when the baudrate is not correct. OctoPrint should keep trying other rates until it 1) finds one it likes or 2) runs out of baudrates to try. My guess is that one of the baudrates selected may be the right one but the printer response is not what OctoPrint expects.
Hello, I had the same problem. I found out by looking at the included WiiBuilder configuration for the Monoprice Cadet that the serial port communicates at 1000000 baud. Yes, that is 1 million baud. you can confirm by connecting to the serial port with a terminal, but the short fix is to modify your local octoprint to show 1 million baud. You would need to modify the octoprint/util/comm.py file to include 1000000 in the list of potential baud rates.