RFID Reader Anti-collision Mechanism

The second important aspect of RFID classification is whether it is necessary to read multiple tags at the same time. In order to realize this function, the technology adopted in communication is (anti-collision) 'anti-collision'. Reading multiple tags at the same time is often talked about as RFID is far superior to graphic codes, but if there is no anti-collision function, the RFID system can only read and write one tag. In this case, if more than two tags are in the readable range at the same time, it will cause a reading error.

Secondly, let's briefly explain the working principle of the anti-collision (anti-collision) function. Even the RFID system with anti-collision (anti-collision) function does not actually read the contents of all tags at the same time. When multiple tags are detected at the same time, the function of searching for signals and preventing collisions starts to operate. In order to search, first determine the search conditions.

1). First, the reader designates a specific number of digits (about 1 to 4 digits) in the electronic tag memory as the number of batches.

2) The electronic label discretizes the response time in batches according to the number of times. For example, when the two-digit number batch is '00, 01, 10, 11', the reader will respond to these four possibilities one by one at different times.

3). If there is only one electronic tag responding at each time, the normal data of this electronic tag can be obtained. After the information is read, the reader sends a sleep instruction (Sleep/Mute) that no longer responds to the electronic tag within a certain period of time to make it dormant to avoid responding again.

4) If several electronic tags respond at the same time at each time, it is judged as 'conflict'. In this case, the number of times recorded by the other two digits in the memory is batched, and the above processing from 2) is repeated.

5) After all the electronic tags have completed their responses, the reader sends them a wake-up command (Wake Up) to complete the information reading of all electronic tags.

In this RFID system equipped with an anti-collision (anti-collision) function, in order to read only one tag, it is repeatedly read and retrieved in batches after several adjustments. Therefore, in the case of reading a certain number of tags at a time, the speed of all tags is different until they are read. The more tags are read at one time, the time required to complete the reading is longer than that of simple calculation. The longer it takes.

Realizing the function of anti-collision (anti-collision) is an indispensable condition for RFID to replace graphic codes in the logistics field. For example, in a supermarket, goods are priced in a shopping cart. In order to achieve this pricing method, anti-collision

      (Anti-collision) function must be complete. On the other hand, when using RFID systems for electronic money and personal authentication, identifying several tags at the same time is the main cause of errors.

The price of an RFID system with an anti-collision (anti-collision) function is more expensive than a system without this function. When individual users are making RFID systems, if there is no need to recognize multiple IDs at the same time, there is no need to choose a reader with anti-collision function.