Hello Team,
This may be a simple question, however, please allow me to clarify.
Our customer will use SN65HVD3086E as a RS-485 full duplex 1:1 communication.
Below would be the general application for multiple TX and RX, which has termination resistor at each end of the bus.
When used in 1:1 (1TX and 1RX), do you need termination resistor at RX side and also at the TX side ?
In this case what is the recommended resistor value that should be used ?
Best Regards,
Kawai
Hi Kawai,
Termination resistors are always a good idea to include in an RS-485 design because they ensure good signal integrity for the application. The typical RS-485 bus impedance is 120 ohms. RS-485 is robust enough though that different termination schemes can be implemented. You could place a 120 ohm resistor at the receiver (RX) and have it work. If the data rate of the application is slow enough, giving you a really long bit time, it is OK to run the RS-485 network unterminated as any ringing that results from the unterminated lines will settle out before the sample point of the uC/uP. Here is a short blog I wrote on this topic:
Please let me know if you have more questions?
