Long-range RFID(~4m) with distance measurement?

Hello PLCS.NET!

I was wondering if there are options in the market which have distance to tag well as ID of the tag? They need to work in about a 4m range. I don't need a high accuracy for the distance, just something that works.

I'm using AB PLCs by the way, with Ethernet as our standard communication. But other options can be explored.

-PreLC

I think I've seen Signal Strength from readers, but that's not necessarily a good proxy for distance.


If you want a good distance measurement, you can look at something called RTLS, but it's a big jump up in price and complexity.

A search came up with research and development of RFID that gives distance based on the time to reflect the signal off the tag.

Nothing presently available showed up other than this for Arduino

We have installed the Alien brand of rfid readers.
it does have its own communications box. I am not sure if we use SQL to interface into the plc 5/80. my co worker has already left for the day. their handheld rfid readers will do 15 ft.
on their big antenna unit, we had to build a cone to focus in the area we wanted to scan so it didn't pick up the tags in the warehouse.


James