1. Overview
The INVT GD20 variable frequency drive (VFD) supports Modbus RTU communication through its RS485 interface. Based on the official INVT technical manual, this article describes the Modbus register address mapping of the GD20 in detail.
2. Modbus Communication Parameters
| Parameter Code | Parameter Name | Description |
|---|
| PC.00 | Communication address | Sets the slave address (1-247) |
| PC.01 | Communication baud rate | Sets the baud rate |
| PC.02 | Data format | Data bits / parity / stop bits |
| PC.03 | Communication protocol | Select Modbus RTU |
3. GD20 Modbus Register Mapping Table
3.1 Control Command Registers
| Modbus Address | Parameter No. | Description | Read/Write |
|---|
| 0x2000 | - | Run command | Read/Write |
| 0x2001 | - | Frequency setting | Read/Write |
3.2 Monitoring Parameter Registers
| Modbus Address | Parameter No. | Description |
|---|
| 0x2100 | PC.00 group | Output frequency |
| 0x2101 | - | Output current |
| 0x2102 | - | DC bus voltage |
| 0x2103 | - | Output voltage |
4. Run Command Word Bit Definition
| Bit | Function | Description |
|---|
| 0 | Forward run | 1 = Forward run |
| 1 | Reverse run | 1 = Reverse run |
| 2 | Forward jog | 1 = Forward jog |
| 3 | Reverse jog | 1 = Reverse jog |
| 7 | Fault reset | Reset on rising edge |
5. FAQ and Troubleshooting
- Check the PC.03 communication protocol setting
- Confirm that the slave address and baud rate match on both sides
- The unit of the frequency setting is 0.01 Hz
- Operate the run command word bit by bit
6. Summary
Core registers for INVT GD20 VFD Modbus communication:
- 0x2000 → Run command
- 0x2001 → Frequency setting
- 0x2100 → Output frequency
- 0x2101 → Output current
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