PLC Monitoring: Modbus TCP vs OPC UA Explained

Connecting PLCs to monitoring software requires industrial communication protocols. Two of the most common are Modbus TCP and OPC UA. Understanding both helps you choose the right approach for your PLC data acquisition project.

Modbus TCP is simple, widely supported, and runs over Ethernet. Many PLCs and HMIs expose data via Modbus TCP. It is ideal when you need to read registers and coils from a variety of equipment with minimal setup. Drawbacks: no built-in security, and you must know register maps. For internal factory networks, it is often sufficient.

OPC UA is a modern, secure, and standardized protocol. It supports rich metadata, subscriptions, and encryption. It is the preferred choice for new installations and when you need security and scalability. Many newer PLCs and industrial gateways support OPC UA.

If your existing PLCs speak Modbus TCP, we can build PLC monitoring software that uses it. If you are upgrading or adding new equipment, OPC UA is worth considering. At Hendoi we develop solutions that work with both. Contact us to discuss your controllers and network.