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2 Supported Modbus RTU functions
The Base PRO controller supports the following functions for Modbus
RTU communication.
Description
Read Coil
Read Discrete Input
Read Holding Registers
Read Input Registers
Write Single Coil
Write Single Holding Register
Write Multiple Coils
Write Multiple Holding Registers
•
Discrete Inputs (read only) and Coils (read and write) are
function codes consisting of 1 bit of data. Most often on or off.
•
Input Registers (read only) and Holding Registers (read and
write) are function codes consisting of 2 bytes (16 bit) of data.
Most often temperature data or settings.
2.1 Frame format: Read Coil
Request
Slave address
Function code
(0x01 – 0xF7)
(0x01)
1 byte
1 byte
Response
Slave address
Function code
(0x01 – 0xF7)
(0x01)
1 byte
1 byte
Response in case of error
Slave address
Error code
(0x01 – 0xF7)
(0x81)
1 byte
1 byte
Example:
Request example:Read Heating/Cooling and Comfort/ECO states
Slave address
Function code
(0x01)
(0x01)
1 byte
1 byte
Response example:Read Heating/Cooling and Comfort/ECO states
Slave address
Function code
(0x01)
(0x01)
1 byte
1 byte
6
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Uponor Smatrix Base PRO Controller X-148 Modbus RTU
Function code (hex)
0x01
0x02
0x03
0x04
0x05
0x06
0x0F
0x10
Starting register address
(0x0000 – 0xFFFF)
2 bytes
Byte count
(N)
1 byte
Exception code
(01, 02, 03, 04, or 06)
1 byte
Starting register
address HI
(0x00)
1 byte
Byte count
(0x01)
1 byte
Number of coils to read
(1 – 2000)
2 bytes
Coil status
(n = N, or n=N+1 if the number of coils to
read can be divided by 8 with a reminder
separated from 0)
n bytes
Starting register
Number of coils to
address LO
read HI
(0x00)
(0x00)
1 byte
1 byte
Coil status
1 to 8 (0x02)
1 byte
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Installation manual
CRC
2 bytes
CRC
2 bytes
CRC
2 bytes
Number of coils to
CRC
read LO
(0x02)
1 byte
2 bytes
CRC
2 bytes
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