Danfoss VLT 6102 - Page 35

VLT® Serie 2800 and VLT® Serie 6000 Modbus RTU
Appendix A
- Examples
Message sent to Modbus RTU from Modbus master
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6+7
Slave
Address
Function Start Addr HI Start Addr LO No. of Points HI No. of Points
LO
Error Check
01 03 14 13 00 02 --
Parameter 514 (5139) = 1413
HEX
Note that the starting address of a register is the parameter number x 10 - 1 in HEX.
Message sent to Modbus master from Modbus RTU
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7+8
Slave
Address
Function Byte Count Data HI (Reg
45140)
Data LO (Reg
45141)
Preset Data
LO
Data LO (Reg
45141)
Error Check
01 03 04 00 00 01 2C --
Byte 3-byte 6: Value 0000012C
HEX
= 300 = 3 Amps
All values are in hexadecimal.
å EXAMPLE 6: Read Parameter 609 [8]
"Log: Reference"
This example shows how to read an index parameter. Holding register 9 - Array Index.
Modbus Function 06
HEX
Preset Single Register
Set Array Index to 8
Message sent to Modbus RTU from Modbus master
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6+7
Slave
Address
Function Register Addr
HI
Register Addr
LO
Preset Data HI Preset Data LO Error Check
01 06 00 08 00 08 --
Message sent to Modbus master from Modbus RTU
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6+7
Slave
Address
Function Register Addr
HI
Register Addr
LO
Preset Data HI Preset Data LO Error Check
01 06 00 08 00 08 --
Modbus Function 03
HEX
Read Holding register
Read value of parameter 609 [8]
Message sent to Modbus RTU card from Modbus master
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6+7
Slave
Address
Function Start Addr HI Start Addr LO No. of
Registers HI
No. of
Registers LO
Error Check
01 03 17 69 00 01 --
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