Advertisement
Revision number: 1.01
Command 03 'Read Holding Registers'
This command is used for reading registers in range 0x0000 ... 0x000B.
Request:
Request code
Start register
Registers quantity
Response:
Response code
Quantity of following data bytes
Data (registers values)
N – quantity of registers
Example:
REQUEST
Request code
Start register High number
Start register Low number
Quantity of High registers
Quantity of Low registers
In this example there is a request for identifier code, which is stored in 2 registers (total size 4 bytes) at
address 0x0002. If there is no RFID identifier within the area of the reader action – then the returned values
will contain zeroes.
Response in case of the request error:
Response code
1 byte
Error code
1 byte
www.technotrade.ua
VRD-485 RFID READER WITH RS-485 INTERFACE
1 byte
2 bytes
2 bytes
1 byte
1 byte
N x 2 bytes
0x03
0x00
0x02
0x00
0x02
0x83
0x02 – start register number is more than 0x000B
0x03 – quantity of requested registers is bigger than memory bounds 0x000B
0x03
0x0000 ... 0x000B
0x0001 ... 0x000B
0x03
N x 2
RESPONSE
Response code
Quantity of data bytes
Most significant byte of RFID identifier
value
Next byte of RFID identifier value
Next byte of RFID identifier value
Least significant byte of RFID identifier
value
Review date: 1 December, 2021
0x03
0x04
0xA4
0x1E
0x45
0xC6
page 10 from 13
Advertisement
