IIoT gateway for isolated machines
A gateway bridges equipment and systems that use different communication methods: it reads factory-floor data, organizes it and delivers it over local Ethernet to SCADA or MES platforms using OPC UA as the integration standard.
Communication and architecture flow
Where does MQTT fit?
MQTT fits remote scenarios such as power substations or other isolated locations with their own power and autonomy. In those cases the gateway can publish telemetry to an authorized broker through an outbound connection, preferably over MQTT with TLS, without opening inbound ports in the industrial network. For plant SCADA and MES, the primary integration remains Ethernet with OPC UA, respecting strict network segmentation and security policies.
Industrial challenge / problem:
Many industrial gateways are expensive. For a machine with hundreds of real-time tags that investment may make sense, but for a water pump, motor, compressor or another isolated node the question is whether a gateway costing about BRL 5,000 is justified. This project will investigate that boundary.
Solution path:
Develop a dedicated board from scratch, with wired Ethernet as a requirement for local SCADA and MES integration, using OPC UA as the communication standard between the gateway and supervisory systems. In an industrial architecture, data should remain inside the plant network by default; only critical remote systems should receive information through controlled paths. The network also needs strict segmentation between machines, supervision and other services. MQTT can complement the solution when a specific message-publishing need exists. The focus is IIoT: availability, predictability, interoperability and safety on the factory floor, not generic connectivity alone.
Project component list:
- Dedicated ESP32 board
- RS-485 interface for Modbus RTU
- Industrial power input
- Signal protection and conditioning
- Ethernet interface with RJ45 connector
- OPC UA for local SCADA / MES integration
- MQTT as complementary communication
Features to be tested:
- Reliable Modbus RTU register reads over RS-485
- Stable Ethernet communication inside the local industrial network
- Expose data through OPC UA to SCADA and MES
- Latency, data integrity and tag-quality identification
- Reconnection after network failure, device restart or power loss
- Operation on segmented networks with restrictive policies
- MQTT over TLS publication for remote telemetry when applicable
What we want to discover:
Obtain an answer based on local Ethernet tests: understand which applications a compact, lower-cost custom gateway serves well and where a complete industrial gateway remains the right investment.