Modbus RTU over 2-wire telco line


Thread Starter

John van Schaick

I have some RTUs with an RS485 interface (2-wire or 4-wire) that have to be connected over long distances via 2-wire telecoms copper wire. We cannot connect the RS485 interface directly.
Does anyone know of modems that can work in a kind of multidrop mode over longer lines? The speed we need is 9600 baud.
Dear friend!

Fistly, pleased give me branch name and part number of yours RTUs. I can give you electrical diagram for RS485 interface.

Second, please tell me how long do you need in your system, I may recomend some solutions.

Bye bye!

Dale Whitchurch

What type of distance are you looking for? What kind of interface are you looking at on the RTUs? Is it a simple 485->485 over distance, or is there another interface in there?

Dale Whitchurch
Sealevel Systems
[email protected]
You can use the MuLogic LLM-336.

It will do multipoint over leased lines or copper wire at 4800 and 9600 bps for Modbus RTU messages without the need for RTS and CTS signals. The transmitter is enabled on incoming RS232 or RS485 data.