USB to TTL using CP2102 module

[alpha91]

Hi all, good day.
I am designing a python application running in Raspberry Pi which send out serial message to print on embedded thermal printer.
the communication is using USB to TTL module (CP2102 chip).
currently my application able to print successfully, but there is one issue is, if the USB to TTL serial is connected to my Raspberry Pi USB since switch ON, it will print out a bunch of weird character.
However, if i remove the USB TTL module and plug in again, everything is fine, it able to print nicely.
Does anyone know what is going on?

 

[barry]

First of all, the CP2102 is USB to UART(not TTL). USB defines a communication protocol; TTL defines logic levels.

It's not clear what you're connecting to your printer, or what protocol your printer uses. But it's pretty obvious that you don't need the converter since without it everything works, right? What made you think you needed it? Does your printer require USB? I suspect not.

Without more information from you, it's hard to tell what's going on.