Joined: 11 Dec 2009
Location: Ottawa, Ontario, Canada
|Dec 11, 2009 4:13 am
First of all, this is a great site. A real gem, and I'm glad I found it. I can tell you know your stuff.
Now what I'd like to discuss is how I should go about having 5 RFID reader devices connected on a single bus. Most of the readers sold can do I2C, RS485, or even USB. I've been steering more towards the RS485 protocol but I'm not entirely sure if this is the best choice. If I understand correctly from your descriptions of this protocol I will have to poll each one of the readers in turn to see if they've read a tag.
Now the problem is...The actual RFID tags could arrive at any moment, even sometime on seperate readers almost simultaneously...is there a way to setup this network of readers so that they are always in a "read" mode, and that anytime they read a tag they would simply send the information on the bus to the master controller? Abviously I would need to implement some sort of buffer into the readers in case the bus was "busy" so that the data from the tag was sent eventually when the bus is no longer "busy"
Am I going down the right path here? What are your thoughts?