Physical connection of EIA-485 daisy chain


Thread Starter

Howard Bales

I am specifying a modbus system that will have multiple slaves on a EIA485 multidop network. I have one type of slave that has a DB9 connector, and one type that has a DB15.

I intend to specify Belden 3107A cable.

I am having trouble finding a suitable 15 pin connector that will accommodate 2 cable connections. I need to specify a connection that is simple for field electricians to wire. No soldering. Screw terminal is best.

This is an industrial environment, so robustness is important.

Thanks for any suggestions.


Howard Bales, PE
Manufacturing Systems Technologist
2020 SW 4th Avenue
3rd Floor
Portland, OR 97201
[email protected]

Chris Parrish

Robustness is important? Then you must solder the connectors, and pot them if possible. There are several companies that make suitable connectors for your needs.

Chris Parrish
Process Control Tech., Sr.
City of Atlanta
Department of Watershed Management
[email protected]
I couldn't find those "suitable connectors" when I had a similar situation. The twisted pair field wiring was in conduit. DB connectors on the slaves.

I had a panel shop fab small enclosure boxes, with DB connectors facing the outside on one side of the box, with conduit access fittings on opposite sides. The twisted pair came in through the conduit and was connected to the DIN rail terminals. The panel shop soldered wiring to the back side of the D connectors and connected those wires to the terminal strips.

The slaves easily connected with heavy duty straight through serial cables from Black Box. The electricians could handle the twisted pair wiring to the terminal strips.

While looking for industrial RJ-45's today, I stumbled across Phoenix Contact's assortment of panel connectors, some of which are DBs at

I had Black Box make up custom adapter connectors and/or serial cablees at reasonable prices several years ago. Don't know if they still offer that service.

Scroll down to 9 pin Dsub combinations.