Sir,
I want to use two serials in project.
How to use that ?(one is for GSM module(USB) and other is for RFID)
I already tried but after 1st scanning and sending sms .
I got error for serial.open.
plz help
Which kind of problem do you have? You can use the in board serial com port for gsm device and a usb port for rfid...
It's very easy.
I normally use raspberry with 2 rfid readers and 4 relays.