Danfoss VFD500 Series User Manual

VFD500 high performance vector control frequency inverter user manualAppendix A Modbus communication protocol
Appendix A Modbus communication protocol
VFD500 series of inverter provides RS485 communication on interface, and adopts MODBUS
communication protocol. User can carry out centralized monitoring through PC/PLC to get
operating
requirements and user can set the running command, modify or read the function codes, the
workingstate or fault information of frequency inverter by Modbus communication protocol.In addition
VFD 500can also be used as a host to broadcast with other VFD500 communication.
A.1 Protocl fomat
RS485 asynchronous half-duplex.
RS485 terminal default data format: 1-8-N-1 (1 start bit, 8 data bits, no parity, 1 stop bit), the default
baud rate: 9600bps. See parameter group set 30.
A.2 Message format
The VFD500 series inverter Modbus message includes the start sign, the RTU message, and the
end sign。
The RTU message includes the address code, the PDU (Protocol Data Uint, the protocol data
unit), and the CRC check. PDU includes the function code and the data section.
RTU frame format：
A.3 Command code instruction
A.3.1 Command code 0x03Read multiple registers or status words
●
Request PDU
Frame start (START)
More than the 3.5 byte transmission time
Target station address
(ADR)
Communication address:1 to 247(0: broadcastaddress)
Command code (CMD)
Command
code
Description
0x03
Read multiple registers of the AC drive
0x06
Write a single register to the AC drive.
0x10
Write Multiple registers to the AC drive.
0x08
Diagnostic command code
Number of function
code
Including the register address (2Byte), the number of registers n(2Byte)
and the register content (2nByte), etc.see A3 in detail
CRC CHK low level
It indicates the replying data or the data waiting to
write-in. CRC 16 check value,During the transmission, high bit is put in
frontand low bit is at the back.see detail in A.5 Chapter
CRC CHK high level
FRAME END
More than 3.5 byte transmission time
Command code
1byte
0x03
initial address
2byte
0x0000～0xFFFF(high 8
bit in front)
128

Danfoss VFD500 Series Specifications

General

Brand	Danfoss
Model	VFD500 Series
Category	DC Drives
Language	English