RS232 to RS485 Convertor with Class 1 Division 2

Hi,

I'm sourcing for a RS232 to RS485 convertor (Class 1 Div. 2), oil and gas application.

We are connecting our Allen Bradley PLC, MLX 1500 (RS232) to DCS (RS485) in Modbus protocol.

Hope someone has experience in such convertors can guide.

Thx.

Try here


http://www.sixnetio.com/

My two favorite RS-485 converter vendors are

www.bb-elec.com

www.robustdc.com

Since the protocol is Modbus RTU, the connection will be half-duplex. You do need to find out if your DCS uses 4-wire or 2-wire RS-485.

You will probably have to inquire with the vendors about their Class 1, Div 2 ratings.

The Allen-Bradley 1761-NET-AIC converter is Class 1, Div 2 for Groups A,B,C,D and uses 2-wire RS-485 signalling with an isolated common wire. Since you are already using Allen-Bradley hardware, this interface device may be ideal if the DCS also uses 2-wire RS-485.

Ken: Thx for ur info, I've chk out the bb & robus comm, but it's isolated devices, not Class 1 Div 2, right? Thx.

Mickey: I've chked out the Sixnet, but can't find any RS232-RS485 convertor, can you please let me know the catalogs number. Thx

The hazardous environment ratings are not prominent in B&B or Robust DC's product data sheets, but that doesn't mean they don't qualify. A-B is accustomed to putting all the agency certifications on the product data sheet because they are accustomed to having to pass a handful of different agency tests wordwide.

Of primary importance is the implementation of Modbus RTU on RS-485 at the DCS end. If you don't know EXACTLY how it's done, you can't make the right selection.

Ken Roach, you are correct, after explaining to our customers, they agree to settle with ADAM, isolated convertor, just cost less than 90USD.

Thx for your inputs.

They don't have converters but they do have modems rated for hazardous areas. Use your own two wires for phone lines.