To communicate with a Delta VFD-M series Variable Frequency Drive (VFD) using the Modbus protocol, you would typically follow these steps:

1. Communication Parameters: Determine the communication parameters required by the Delta VFD-M, such as baud rate, data bits, parity, and stop bits. These parameters should match the settings configured in your Modbus master device (e.g., PLC, HMI).

2. Physical Connection: Connect the RS-485 communication port of the Delta VFD-M to the RS-485 port of your Modbus master device using an appropriate RS-485 cable. Ensure proper wiring of the RS-485 cable, including the connections for A (positive) and B (negative) signals.

3. Address Configuration: Each Delta VFD-M connected to the Modbus network must have a unique Modbus address. Refer to the Delta VFD-M user manual for instructions on setting the Modbus address.

4. Modbus Function Codes: Familiarize yourself with the Modbus function codes supported by the Delta VFD-M. These function codes determine the type of operation (e.g., read holding register, write single register) that can be performed on the VFD.

5. PLC/HMI Configuration: Configure your Modbus master device (e.g., PLC, HMI) to communicate with the Delta VFD-M using the appropriate Modbus communication parameters and function codes. Set up the communication channels and define the addresses of the VFD parameters you want to read or write.

6. Testing and Troubleshooting: Test the communication between your Modbus master device and the Delta VFD-M. Verify that you can read and write VFD parameters as intended. If you encounter any issues, check the wiring, communication settings, and Modbus addressing for errors.

7. Integration with Control System: Once communication is established successfully, integrate the Delta VFD-M into your control system application. Use the Modbus communication capabilities to monitor and control the VFD parameters as required for your application.

By following these steps, you should be able to communicate with a Delta VFD-M series VFD using the Modbus protocol and integrate it into your industrial automation system.

VFD-M Inverter Communication Configuration
In addition to the basic inverter setting parameters, we need to set the communication parameters as follows:

Pr00: 03 – Set Frequency by RS485
Pr01: 04 – Start/Stop control by RS485
Pr088: 01 – Modbus Slave Station #1
Pr089: 01– Baud Rate 9600bps
Pr092: 04 – MODBUS RTU ( E, 8,1 )
Pr157: 01 – Modbus Mode

read 4 values:

2103H: Output Frequency
2104H: Output Current
2105H: DC-BUS Voltage
2106H: Output Voltage
Start/Stop control register: 2000H >>> Set Value folow to below:

Run Forward (FWD): = 18 (0000.0000.0001.0010)
Run Reserved (REV): = 34 (0000.0000.0010.0010)
Stop: = 1 (0000.0000.0000.0001)
Frequency Setting: 2001H