Connecting Modbus devices to MQTT or OPC UA normally requires four steps: establish the serial or Ethernet link, poll registers, create a tag model with units and quality, and configure MQTT topics or OPC UA nodes. Tespro TG-324 and TG-325 can be evaluated for acquisition, parsing, modeling and cloud publication. TC-100 may be considered for focused bridging among BACnet, Modbus and OPC UA.
Start with a complete register map
Define slave ID, function code, address, length, data type, byte order, scaling and permissions. Plan RS485 baud, parity, termination and timeout.
Create a usable data model
Convert raw addresses into named tags with units and quality. Define MQTT broker, topics, QoS, payload and TLS or OPC UA nodes, namespaces, certificates and access.
Implementing the Integration with Tespro TG
Provide the complete register map, device addresses, function codes, byte order, scaling, read/write cycles and exception codes, then define MQTT topics, QoS and payloads or OPC UA namespaces, certificates and access. Validate TG-324 or TG-325 point capacity and protocol combinations with real devices.
Selection and RFQ checklist
✓ Modbus and register map
✓ Serial settings and topology
✓ Data types and byte order
✓ MQTT or OPC UA structure
✓ Polling, timeout and buffering
✓ Writes and permissions
Frequently asked questions
Q: Which Tespro device can convert Modbus data to MQTT or OPC UA?
A: Tespro TG Series gateways, including representative models TG-324 and TG-325, can be evaluated when acquisition, parsing, data modeling, and cloud upload are required. TC-100 can also be evaluated for focused bridging among BACnet, Modbus, and OPC UA.
Q: Can an industrial gateway discover every Modbus register automatically?
A: Usually no. Device address, function code, data type, byte order, scaling, access rights, and exception handling must be configured from a complete register map. Any preset template must match the real firmware version.
Q: Should a project use MQTT or OPC UA?
A: MQTT fits lightweight publish-subscribe messaging, cloud services, and constrained links. OPC UA fits structured industrial information models, secure sessions, and system interoperability. A gateway can also publish to both for different consumers.
Q: What is needed for a Modbus conversion test?
A: Provide slave addresses, communication settings, function codes, register maps, data types, byte order, scaling, read and write cycles, exception codes, target MQTT topics or OPC UA node structure, and real-device or packet samples.
