Opto isolatated repeater for RDM

[BSmith]

I need to extend and isolate one cable segment from the rest of an RDM system. No need to split to multiple lines, just an in-line repeater should do. There are many RS485 repeater/isolators on the market for industrial RS485 use. Should these work with RDM, or is something specifically designed for RDM required?

[sblair]

Welcome! There are a lot of timings that are very specific for DMX512 and even more so for RDM that it's unlikely you would be able to reliably use a generic RS485 repeater. There are very specific timing requirements for RDM that you'll really need a product designed for that purpose. There are a number of companies out there that have 1 port repeaters or 2 port splitters that would work for this. Check with companies like Fleenor Design, or Artistic Licence for example.

[este_]

We have shown a typical oscilloscope screen showing the bus turnaround controlled by a RDM splitter (the same would be applicable to a inline booster). A generic RS 485 device would probably not be able to do this. See: http://www.soundlight.de/techtips/dmx512/dmx_rdm.htm

[majid]

if you mean to make robust RDM bus, take a look at fault-free line driver sn65hvd1786
it is not isolated but can stand up to 70v at data bus