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Smart Card Readers
Smart Card Readers or Terminals obtain card information and perform necessary operations, for example, opening a door, writing back to the Smart Card, etc. While a reader usually interfaces with a PC, a terminal is a complete processing system.
Contact Readers A contact reader requires a physical connection. A card must be inserted into the reader. This communication is considered more secure, faster and enables large data transfer. The Protocol Type Selection (ISO7816-3) allows the speed up to 115 kilo baud.
Contact Readers usually interact with a PC via the interfaces that include RS232 serial ports, USB ports, PCMCIA slots, floppy disk slots, parallel ports, infrared IRDA ports and keyboards.
Contactless Readers
Contactless Readers communicate with the card over radio frequency.
The card must be close to the reader. The main standard is ISO 14443 (MIFARE), followed by the EMV standards.
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Application Protocol Data Units, a standard set of communications commands
Application Protocol Data Units (APDU) follow ISO 7816-3 standards.
APDUs commands are executed at a very low layer of any software application, which works with a reader.
Most terminal SDKs come in some form of C, C++ or C # with a customized API for a specific platform.
They are typically in some form of C, C++ or C # and will have the header files included. In some cases such SDK allows developers to work with the readers from more than one vendor.
After the handshake between a reader and a card, developers usually use APIs that allow to send standard ISO commands in their standard ISO format as well as some proprietary commands designed for specific readers and cards.