Should I Connect the 120Ω Resistor on UART-to-RS485 Converter for 2-Module Communication?
Hello,
Got a uart-to-rs485 converter board from the AliExpress .
Its schematic is very close to this one
It has a 120ohm resistor at data lines however it is not connected (R0 is absent).
As far as I can understand it is something related to impedance matching.
The question is: should I leave it like this (open) or short if all I want is to connect 2 identical modules to make a communication line between two UARTs? The picture below is what I bought, R13 seemed to be R0 from the pic above
Got a uart-to-rs485 converter board from the AliExpress .
Its schematic is very close to this one
It has a 120ohm resistor at data lines however it is not connected (R0 is absent).
As far as I can understand it is something related to impedance matching.
The question is: should I leave it like this (open) or short if all I want is to connect 2 identical modules to make a communication line between two UARTs? The picture below is what I bought, R13 seemed to be R0 from the pic above
Solution
I would say you should not short it. Leave it open as it is in the schematics diagram. If it's a Uart line then it shouldn't have an issue. But I would say you should check the datasheet and confirm what the manufacturer said about this.
