Case study of the access to a company car park with open source technology and a single Industrial Shields M-Duino PLC. The PLC reads RFID cards over SPI, checks them against a user list kept on its own microSD card, opens the gate with a relay, shows the result on a panel and takes changes to the list from a server.

The PDF covers the challenge, the three steps (read and decide, keep the list up to date, show and record), the system architecture with the signal table and the hardware used. Interactive version: RFID parking access case study online.