Huanyang VFD RS485 commands (pseudo Modbus)

hunayang-rs485-commands.md

Hunayang RS485 commands

Hunayang inverters claim to be Modbus compatible - they are not :-( So here i try to create a nice list of all commands and their meaning.

I assume the use of the RTU mode.

Parameter settings

• PD001: 2 (Source of run commands: communication port)
• PD002: 2 (Source of operating frequency: communication port)
• PD163: 1 (Communication address: 1)
• PD164: 1 (Communication Baud Rate: 9600)
• PD165: 3 (Communication Data Method: 8N1 RTU)

Functioncode 01 - Read function code data

slave address function code data length function data crc

If function data is 2 bytes, data length is 0x03, if just 1 byte 0x02

Unfortunately the complete manual says nothing about themeaning of function data, so i have no idea what this function really does

Functioncode 02 - Write function code data

slave address function code data length function data crc

If function data is 2 bytes, data length is 0x03, if just 1 byte 0x02

Unfortunately the complete manual says nothing about themeaning of function data, so i have no idea what this function really does

Functioncode 03 - Write control data

slave address function code data length control data crc

Data to the VFD

0x01 0x03 0x01 0x08 0xF1 0x8E

• 0x01 = slave address
• 0x03 = function code
• 0x01 = request length
• 0x08 = stop
• 0xF1 0x8E = CRC16

The manual says possible control data values are:

• 0 = run
• 1 = for
• 2 = rev
• 3 = stop
• 4 = r/f
• 5 = jog
• 6 = jogf
• 7 = jogr

Its not entirely clear why 8 stops the VFD but maybe the possible options are bit positions in a byte rather than actual values.

Response from the VFD

0x01 0x03 0x01 0x09 0x30 0x4E

• 0x01 = slave address
• 0x03 = function code
• 0x01 = request length
• 0x09 = ??
• 0x30 0x4E = CRC16

The manual says possible control status responses are:

• 0 = run
• 1 = jog
• 2 = r/f
• 3 = running
• 4 = jogging
• 5 = r/f
• 6 = Braking
• 7 = Track start

Thanks for your helpful document! While doing further research, I've found a different copy of the manual that talks about what function data actually means. They correspond directly to the PDxxx functions that you can set with your rotary valve. The READ_FUNC command returns an integer encoded as big-endian bytes, although different functions have different units which you have to check the manual for. Hope this helped!

Here's a link to the manual I used:
https://www.nvcnc.net/wp-content/uploads/2021/06/HuanYang-VFD-Manual.pdf