RFID Processor in a RFID system
The processor unit is the link between data carrier and host control system. It manages two-way data transfer between data carrier and R/W head and provides buffer storage. The processor unit uses the R/W head to write data from the host control system to the data carrier or reads the data from the carrier and makes it available to the host control system.
Host control systems could include:
– A control computer (e.g. industrial PC)
– A PLC.
The processor unit is also called the reader, especially in logistics, since only the reading function is used there. Its main function is the interface between data carrier, read or write data, and a controller. The processor unit will generate a command and send that signal out via the read/write head (the antenna) as magnetic or electromagnetic wave.
In the case of passive data carrier, this signal powers the data carrier allowing it to transmit its data through its own internal antenna. The generated command can be a read or a write request. Hence the data carrier will react respectively i.e. sends the required data or expected data to store.
Double Bit Header:
To ensure complete transmission of all data in the data buffer, the control bits in the data buffer's first and last byte (bit header) are transmitted and compared for each R/W head. If both bit headers are the same, then the data has been fully updated and can be transmitted. This means that the data for each R/W head is only valid if both bit headers are the same. Thus, the host control system must also compare the bits in the bit headers.