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Hello again.

A little while ago, I purchased a Simultaneous RFID reader, a RedBoard, an aerial, and the other necessary accoutrements, from SparkFun, and I'm glad to say I've put them together and they're working as expected.

My project now requires me to combine signals from multiple -- at least 2, no more than 4 -- antennae. I've been told elsewhere on this forum that it's impossible to stick more than one aerial onto a single Simultaneous RFID reader. Therefore, to build a system with, say, 2 antennae, I'd have to have 2 Simultaneous RFID readers. That's not, in and of itself, a problem; my company's pockets are sufficiently deep. But what's the least atrocious way of building the system so that the data from both reader-antenna pairs are combined into one stream?

Would it be feasible and advisable to link one RedBoard to both readers? If not, and each reader will need its own RedBoard, how can I combine the output into one wire/data stream? Bear in mind that the device which this system is supposed to be connecting to only has one or two free USB ports.

Hello Tom, and thanks for your post.

You probably wouldn't be able to combine two SRTRs on a single Uno and have them work satisfactorily. At least not if they were both reading tags at the same time. You might be able to get away with that on a Arduino that has more than one free hardware UART though. A Mega has three free hardware UARTs and might be fast enough to process and combine two serial streams at the same time.

You would need to rewrite the library to handle more than one board at a time. I don't believe our current code can handle more than a single SRTR at a time.

Another possibility would be to use two Uno/RedBoard + SRTR combos both connected to a computer and then combine the streams in software on the computer. I don't have a tutorial anywhere that shows how to do something like that though unfortunately.

It might cost more, but a RFID reader that supports multiple antennas might be a lot simpler to use since a device like that is made to do what you're trying to attempt from the get go. We don't carry it, but something like the ThingMagic M6e UHF RAIN RFID might be a better alternative for you, plus it already works with the Universal Reader Assistant software the manufacturer has for it.