Written by the layer that has to parse both sides into one schema. Every comparison ends the same way: the protocol choice stops mattering once the output is canonical, but the reasons to pick one differ, and they are real.
| Comparison | Why people ask |
|---|---|
| Modbus TCP vs OPC UA | The default retrofit question. You have a plant of Modbus devices, a new machine arrives speaking OPC UA, and someone has to decide what the site standard is. |
| Modbus TCP vs MQTT / Sparkplug B | The question behind every gateway purchase: should the device be polled, or should it publish? |
| MTConnect vs OPC UA | The machine-tool standards question. Both claim the shop floor, and several controllers now expose both simultaneously. |
| BACnet/IP vs Modbus TCP | The question that appears the first time a data centre or a factory tries to put building systems and process equipment on one dashboard. |
| Modbus RTU vs Modbus TCP | Not really a protocol choice, a wiring choice. Same data model, same registers, entirely different operational life. |
| MQTT / Sparkplug B vs OPC UA | The architecture question for a greenfield IIoT build: broker in the middle, or client-server to each asset? |
| PROFINET / S7 vs EtherNet/IP | The one that is really a question about which controller vendor you already own. |
| SunSpec vs Modbus TCP | The solar and storage question. SunSpec is not an alternative to Modbus, it runs on top of it, but the choice of whether to implement it is real. |
| DNP3 vs Modbus TCP | The utility SCADA question, and the one place where Modbus's simplicity is genuinely a liability. |
| J1939 (CAN) vs OPC UA | The mixed-fleet question: a company that runs both vehicles and a plant, and wants one data layer over both. |