Noob need guidance on a multi rfid reader system.

To begin with, I am new to arduino. That being said, I have been tasked with a project at work which involves reading up to 240 rfid's. The premise behind the system is this:

I will have 8 rows of 10 rfid readers attached to an arduino nano. Each will be connected through rs485 (max485 module) to an arduino mega2650 (middleman). The middleman's job is to relay the read command from a plc to the individuals on that row, and relay the UID from the rfid back to a plc over rs485.

Again, I am new to arduino. I have gone through my starter kit examples and am ready to start to tackle this project. I think a switch/case setup would work best for what I am trying to accomplish, but I could be wrong. Any guidance, insight, direction, or help would be much appreciated.

I have tried to upload an image of my circuit for analysis, but the forum will not let me.

This Forum is mainly supporting none commercial hobbyists and helpers answering do this without being payed.
There is a commercial bransch called Gigs and Collaborations where business arrangements can be done. Let's se what the administrators say.

Well, seeing as I am not looking for someone to write my code and only looking for advice, I don't see what the issue would be.

When you write: "I have been tasked with a project at work", then that is commercial work.

Best advice is to start with getting the communication between the two Arduinos working first.

Paul