If you’re working with Delta PLC and need to communicate with the TDA-09C DIN-Rail Weight Transmitter over Modbus RTU, this guide will help you complete the connection quickly.
After several communication tests, we successfully established stable communication between a Delta PLC and the TDA-09C using the standard Modbus RTU protocol.
Hardware Used
- Delta PLC (DVP Series / AS Series)
- TDA-09C Weight Transmitter
- RS-485 Communication
- Modbus RTU Protocol
Communication Parameters
Configure both the PLC and the TDA-09C with identical communication settings.
| Parameter | Value |
|---|---|
| Protocol | Modbus RTU |
| Baud Rate | 9600 (or according to your transmitter) |
| Data Bits | 8 |
| Parity | None |
| Stop Bits | 1 |
| Slave Address | 1 (example) |
The TDA-09C supports standard Modbus RTU communication, allowing any Modbus master—including Delta PLCs—to read measurement registers using standard function codes such as 03 (Read Holding Registers).
Register Mapping
According to the TDA-09C manual:
| Register | Description |
|---|---|
| H1 | Real-time Weight |
| Data Type | 32 bit |
Note: Depending on your firmware version, register addresses may differ slightly. Always verify them with the transmitter manual.
Delta PLC Program
After communication:
- D1 = Current Weight Value
If decimal scaling is enabled in the transmitter, convert the raw value accordingly.
Example:
Raw Value : 12345
Actual Weight : 1234.5 kgRS-485 Wiring
PLC RS485 (+) -------- TDA-09C A(+)
PLC RS485 (-) -------- TDA-09C B(-)
GND (optional) -------- GNDIf communication is unstable:
- Swap A/B wires.
- Add a 120Ω termination resistor if the cable is long.
- Ensure all devices share the same baud rate and slave address.
Communication Tips
If the PLC cannot read the transmitter:
✔ Verify the Slave ID.
✔ Check baud rate, parity, and stop bits.
✔ Confirm the correct Modbus register.
✔ Test communication first with Modbus Poll on a PC.
✔ Verify RS-485 polarity.
✔ Make sure only one device uses the same slave address.
Testing Result
After configuring the communication correctly, the Delta PLC reads the weight data from the TDA-09C reliably and continuously.
This solution has been tested successfully in industrial batching and weighing applications.
Download
The project package includes:
- Delta PLC Sample Program
- Communication Parameters
- Register List
- Wiring Diagram
- Modbus Test Example
If you’d like the complete PLC project, feel free to leave a comment or contact us.
Keywords
Delta PLC, TDA-09C, Weight Transmitter, Modbus RTU, RS485, Delta DVP PLC, Industrial Automation, Weighing System, PLC Programming, Load Cell, Modbus Communication
