I'm working on a project with 3 RFID readers connected and powered by USB. Then read data and send it serial to PC for further processing.
The solution works flawless for 40 minuts and then the USB connections are closed.
I have a serial monitor software to log what's going on. And every 40 minutes the ports are closed. This will happen no matter if the RFID readers are active or no data at all is send over the COM port.
The setup contains 3 readers. I've tried connecting each of them to a separate USB hub with external power supply but they will all fail exactly 40 minutes after being opened.
Then I tried having 2 on the external hub and 1 directly attached to the PC. Same result.
So I don't think it's the HUB or the power supply to the RFID boards as this happens both with the hub and the PC.
I'm starting to think if it could be the RFID library (newest version from Miguel Balboa) or a watch dog that needs to be reset. It's strange that it's 40 minutes each run before the port is closed. Well - it's not exactly 40 minutes !! But it's within +/- 1 minute.
Any ideas out there for what to check?