Operating instructions

VLT
®
2800, VLT
®
6000 HVAC and VLT
®
8000 AQUA Modbus RTU
Appendix A
- Examples
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.
■ 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 para
meter 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 --
Message sent to Modbu
s master from Modbus RTU
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 6+7
Slave
Address
Function Byte Count Data HI Data LO Error Check
01 03 02 01 90 --
Note that the starting address of a register is the
parameter number x 10 -1 in HEX.
Byte 3+byte 4: 0190
HEX
=400=40%
All values are in hexadecimal.
MG.10.S2.02 - VLT is a registered Danfoss trademark
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