Reference
Last revision 2026/01/06
This article explains the communication protocols of UHF RFID Module RS485, focusing on command, response, and information frame formats for RFID data transfer.
Communication Protocol Description
UHF RFID MODULE-RS485, the remote RFID tag reader module, transfer immobilize data format to achieve read-write. There are three common data frame format.
1. The first type:
Command frame is the data frame for operating the reader, the data transfer from host to slave, and the format as follow.
| PacketType | Length | Command Code | Device Number | Command Data | ... | Command Data | Command Data | Checksum |
|---|---|---|---|---|---|---|---|---|
| 0xa0 | n+3 | 1 byte | 1 byte | Byte 1 | Byte n-1 | Byte n | cc |
- Packet Type is a packet type domain, the command frame packet type is fixed at 0xa0;
- Length is a packet length domain, representing bytes number of frame after Length;
- Command Code is a command code domain;
- Device Number is a device number domain, when usercode, the device number, is 00, this data will be sent to group;
- Command Data is the parameter domain of command frame;
- Checksum is checksum domain, the provisions of checksum range is from packet type domain to the last byte of parameter domain. It’s need to compute the checksum to detect error after the module receives command frame.
2. The second type:
Response frame of reader command completion is the data frame with immobilized length, the data transfer from slave to host, and the format as follow.
| PacketType | Length | Command Code | Device Number | Status | Checksum |
|---|---|---|---|---|---|
| 0xe4 | 0x04 | 1 byte | 1 byte | 1 byte | cc |
- Status is the status field，show the status or result after the reader complete the command by PC, the description as follow:
| SN. | value | name | description |
|---|---|---|---|
| 1 | 0x00 | ERR_NONE | Command complete |
| 2 | 0x02 | CRC_ERROR | CRC check error |
| 3 | 0x10 | COMMMAND_ERROR | Illegal command |
| 4 | 0x01 | OTHER_ERROR | Other error |
3. The third type:
Information frame is the data frame sent to host, such as used to send a tag to host, the data transfer from slave to host, and the format as follow.
| PacketType | Length | Response Code | Device Number | Response Data | ... | Response Data | Checksum |
|---|---|---|---|---|---|---|---|
| 0xe0 | n+3 | 1 byte | 1 byte | Byte 1 | Byte n | cc |
- Response Code is the information code field, the value selection determine the type of information;
- Response Data is the field of the parameter in information frames.
Other Command Instructions
As follow is some common command from host , and more information and details please refer to the UHF RFID MODULE technical documentation.
| Read tags | Kill tags | Stop reading tags | restart tag identification function | Control BUZZER |
|---|---|---|---|---|
| A0 06 80 00 01 02 01 D6 | A0 08 86 00 00 12 34 56 78 BE | A0 03 A8 00 B5 | A0 03 FC 00 61 | A0 04 B0 00 00（close） AC A0 04 B0 00 01（open） AC |
When the RFID tag reader module power on, and after a short "beep" sound, the module will enter continuous card-reading mode. Put the tag above the module, the module will begin to read the cards.
For example, you can stop the card-reading by send a data through the serial port (stop reading data is A0 03 50 00 D). And if this operation is success, the module will return E4 04 50 00 00 C8. If fails, return data E4 04 50 00 (other value) C8.
Module has destroyed, lock and other special functions. If once the tag be destroyed, the tag will can never use again. So, please use these function cautiously!
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