Electronic – RS485 minimum node spacing – 3 x RS485 device on PCB


I would like to ask something about RS485 minimum node spacing which is described in (Page 5)

TI Design guide

I would like to create device which consists from 3 existing RS485 devices. My plan was that I put these 3 devices together on single 2 layer PCB and connect them via single RS485 line (A, B). According to material above this shouldn´t be a good idea because there will be very small length traces between these devices.

Do you have any experience with this approach of placing more RS485 devices on same board?
Is there any technique which could help the signal integrity?


Best Answer

termination is only required on long lines with high data rates. The purpose of the termination is to make the end of line impedance same as wire impedance to avoid reflections of the wavefront. But this is totally unnecessary on a short bus.

My company manufacturers 100,000+ devices a year (for 10+ years) with a 2 meter RS-485 bus and we don't use terminators.

There are many app. notes on this.