RS485 communication-Is ground connection essential

Jayaram C B

Other Parts Discussed in Thread: ISO3086

Hi,

In one of our projects we are intending to use ISO3086 isolated transceiver.We are having 4 similar modules (with this transceiver) in a rack and the RS485 outputs of these modules are terminating to a common line of the back plane board. We are planning to use the same 5V supply for this transceiver as well as instrumentation amplifier which processes the field input signal.As per Isolated RS-485 Reference Design application report (http://www.ti.com/lit/an/slla299/slla299.pdf), the ground GND2 needs to be connected to return path of the device connection. Is this connection an essential one? Or can we ignore this ground connection? Pl advice.

Regards,

Jayaram C B

over 12 years ago

0 John Griffith over 12 years ago

TI__Mastermind 21811 points

Hi Jayaram,

Sorry that this was not answered sooner. RS485 and ISO products are supported in the Industrial Interface Forum:

http://e2e.ti.com/support/interface/industrial_interface/f/142.aspx

The return (RTN) does not need to be wired between all the nodes. Since they are isolated, the potential of all the isolated sides of the nodes will float to the same potential.

Thanks,

John

0 Jayaram C B over 12 years ago in reply to John Griffith

Intellectual 370 points

Hi John,

Thanks for your reply

Regards,

Jayaram C B

Interface

Interface forum

RS485 communication-Is ground connection essential