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8 l Uponor Smatrix Base PRO Controller X-147 Modbus RTU interface l Installation manual
2.3 Frame format: Read Holding Registers
Request
Slave address
(0x01 – 0xF7)
Function code
(0x03)
Starting register address
(0x0000 – 0xFFFF)
Quantity of holding registers to read
(0x0001 – 0x007D)
CRC
1 byte
1 byte
2 bytes
2 bytes
2 bytes
Response
Slave address
(0x01 – 0xF7)
Function code
(0x03)
Byte count
(2*N)
N = quantity of registers
Holding register
CRC
1 byte
1 byte
1 byte
2*N bytes
2 bytes
Response in case of error
Slave address
(0x01 – 0xF7)
Error code
(0x83)
Exception code
(01, 02, 03, 04, or 06)
CRC
1 byte
1 byte
1 byte
2 bytes
Examples:
Request example: Read setpoints (21.0 ˚C / 69.8 ˚F = value 689, 0x02BA),12 channels
Slave address
(0x01)
Function code
(0x03)
Starting register
address HI
(0x00)
Starting register
address LO
Start at 1 (0x00)
Quantity of holding
registers to read HI
(0x00)
Quantity of holding
registers to read LO
12 channels (0x0C)
CRC
1 byte
1 byte
1 byte
1 byte
1 byte
1 byte
2 bytes
Response example: Read setpoints (21.0 ˚C / 69.8 ˚F = value 689, 0x02BA),12 channels
Slave address
(0x01)
Function code
(0x03)
Byte count
(0x18)
Holding register
HI (channel 1)
(0x02)
Holding register
LO (channel 1)
(0xBA)
... Holding register
HI (channel 12)
(0x02)
Holding register
LO (channel 12)
(0xBA)
CRC
1 byte
1 byte
1 byte
1 byte
1 byte
...
1 byte
1 byte
2 bytes
Request example: Read setpoint (21.0 ˚C / 69.8 ˚F = value 689, 0x02BA), channel 10
Slave address
(0x01)
Function code
(0x03)
Starting register
address HI
(0x00)
Starting register
address LO
Start at 10 (0x09)
Quantity of holding
registers to read HI
(0x00)
Quantity of holding
registers to read LO
1 channel (0x01)
CRC
1 byte
1 byte
1 byte
1 byte
1 byte
1 byte
2 bytes
Response example: Read setpoint (21.0 ˚C / 69.8 ˚F = value 689, 0x02BA), channel 10
Slave address
(0x01)
Function code
(0x03)
Byte count
(0x02)
Holding register HI
(0x02)
Holding register LO
(0xBA)
CRC
1 byte
1 byte
1 byte
1 bytes
1 bytes
2 bytes