Internet PLC Forum

General => Technical support => Topic started by: prosper on February 25, 2004, 01:09:30 PM

Title: 5V analog reference voltage
Post by: prosper on February 25, 2004, 01:09:30 PM

I am wondering if it is possible to use the 5v analog reference voltage as supply for a RS485 network?

Thanks in advance.

Title: Re:5V analog reference voltage
Post by: support on February 25, 2004, 07:49:22 PM

The RS485 network does not need a "supply". But for long distance it is prefered to use two 560 Ohm resistor to pull the "+" signal line to +9V and "-" signal line to 0V to give the RS485 bus a "bias" voltage. You may be able to use the 5V analog reference as a high bias on the master node although a +9V supply will be better. Do not put multiple biasing on the RS485. Just on one or two ends of the RS485 bus will do.