I have some RFID readers type MFRC-522 and a Arduino Mega2560. The communication between MFRC522 and Arduino is over the SPI protocol. When I use short cables (+/- 10cm) it works fine, but I want to install the readers at +/- 7 meter from the location of the Arduino.
I read something about an convertor to RS422 like the MAX485.
Has somebody experience with this device, and will it work for my project, as describe above.