switching rs 485

Avi Shriki

Other Parts Discussed in Thread: TS3A4741

Hello,

I'm trying to figure out how to switch rs-485 data lines (+ and -). I want to do this because my application does not support the normal bus topology and it must be like a star topology. I was thinking TS3A4741 would be a good choice, but i'm not really sure. If someone could recommend a product that switches the data lines and is ideally dpst I would appreciate it.
Thanks,
Avi

over 8 years ago

0 Ron Michallick over 8 years ago

TI__Guru*** 145236 points

Avi,

I suggest a RS-485 device at every star node. The RS-485 device will handle the ESD, and the -7V to +12V common mode range.

On the logic side of the RS-485 device (D & R pins), you can use a switch or any logic device.

0 Avi Shriki over 8 years ago in reply to Ron Michallick

Prodigy 60 points

What i'm concerned about is the signal reflections that are cause by a star node configuration. The switches would allow me to communicate with one node at a time and significantly reduce the reflections. I'm just not sure which switches I should be using.

0 Adam Torma over 8 years ago in reply to Avi Shriki

TI__Mastermind 45370 points

Avi,

I'm not really sure what your RS-485 signals look like but in this post describes some parameters of typical RS485 signals.

If these parameters are correct I used the ti.com switch selection tool to filter the switches that meet these parameters.

Thank you,

Adam

Switches & multiplexers

Switches & multiplexers forum

switching rs 485