How to set up Modbus registers on a PLC for Modbus TCP to DNP3 protocol conversion

Question:

Hello everyone, I am in need of assistance with setting up Modbus registers from a third-party device on a PLC in order to convert Modbus TCP to DNP3 protocol. I am new to this process and unsure of the steps needed. Can anyone provide guidance on the logic required to configure these registers on the PLC?

Top Replies

In order to better understand your setup, we need more details on your communications architecture. Is your device acting as a client, serving registers to the PLC? If so, the PLC would be sending requests and the device would respond with replies. Are there any other devices attempting to retrieve information from the PLC using DNP3? Additionally, it would be helpful to know the manufacturer and model of the PLC. This information will help us provide more tailored solutions to meet your needs.

Thank you for your prompt reply. The device is currently transmitting registers to the PLC, and you are indeed correct. The DNP3 protocol is essential for grid operators seeking to establish a connection with the device for site control purposes. In this case, an ABB PLC model PM 5650 2ETH is being utilized.

If you're looking to set up Modbus TCP 'scanning' on a specific PLC, I can guide you through the process. Some PLCs support this feature where you can specify which registers to read from another device and set a time interval. However, most PLCs will require you to write PLC programming using their provided instructions for Modbus register reads. This typically involves setting up the IP address of the device, selecting the Modbus function code (usually number 3 for reading holding registers), specifying the number of registers to read, the address of the first register, and other relevant information. To successfully implement this, you'll need to familiarize yourself with the Modbus protocol specification, which can be downloaded for free from the Modbus organization. Additionally, you'll need to understand the Modbus settings for the device, including setting up the IP address, subnet, gateway address, and ensuring it's using the default Modbus TCP port 502. Familiarizing yourself with the device's Modbus 'register map' is also crucial, as this information is key to successful communication. Before attempting to set up communication with the device through your PLC, I recommend testing connectivity from a computer using various software tools. If you need assistance with this step, feel free to reach out to me. The PLC class outline available at CorsairHMI.com also offers some introductory Modbus information that may be useful. Lastly, make sure to study the documentation for the Modbus read instructions specific to your PLC model. Once you've completed these steps, you can then proceed to investigate the DNP side of the setup.

Hey there, happy to help! The process of setting up Modbus registers in a PLC largely depends on your specific PLC model. However, the general steps would involve setting up a Modbus map, establishing the TCP connection, and creating your Modbus-Poll setup. You'll need to know what specific Modbus registers are being used by the third-party device, so make sure you have that information handy. For converting Modbus TCP to DNP3, you'll primarily need a protocol gateway or convertor. The complexity of this task depends on the specifics of your setup, so remember that there's no harm in seeking help from your PLC or third-party device manufacturer's technical support for a smoother transition. Stay patient and persistent, it's a steep learning curve but you'll get there eventually.

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Frequently Asked Questions (FAQ)

FAQ: FAQs:

Answer: 1. How do I set up Modbus registers on a PLC for conversion to DNP3 protocol? - To set up Modbus registers on a PLC for conversion to DNP3 protocol, you need to map the Modbus registers from the third-party device to specific memory locations on the PLC. This mapping can be done through programming the logic on the PLC to read the Modbus registers and then convert the data to DNP3 protocol format. 2. What are the steps involved in configuring Modbus registers on a PLC for Modbus TCP to DNP3 protocol conversion? - The steps typically involve identifying the Modbus registers on the third-party device, mapping these registers to memory locations on the PLC, writing the logic on the PLC to read and process the Modbus data, and finally converting the data to the DNP3 protocol format. It is essential to ensure compatibility and proper communication settings between the devices.

FAQ: 3. Is there any specific guidance or best practices for setting up Modbus registers on a PLC for protocol conversion?

Answer: - It is recommended to refer to the PLC and third-party device's documentation for register mapping details and protocol specifications. Additionally, testing the communication between devices thoroughly and monitoring data exchange during the setup process can help identify and resolve any issues effectively.

FAQ: 4. What programming knowledge or skills are required to configure Modbus registers for Modbus TCP to DNP3 protocol conversion on a PLC?

Answer: -

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