Modbus to MQTT
Convert Modbus registers into clean, reusable MQTT topics for analytics, applications and downstream operational systems.
Legacy register data, ready for modern event-driven systems.
OTDataMule polls only the registers you define, converts raw addresses into meaningful payloads and publishes them to an approved MQTT broker. Connection management, local buffering and controlled retries keep the data stream stable around real industrial constraints.
From Modbus registers to governed MQTT messages
OTDataMule polls approved register ranges, decodes device-specific values and publishes a stable topic and payload model. Persistent buffering protects the plant-facing collection cycle when the MQTT broker is unavailable.
{
"asset": "pump-07",
"pressure_bar": 6.4,
"quality": "good"
}
plant/area-a/pump-07/telemetryConfirm zero/one-based addressing, function codes, signedness, register width and vendor word order.
Group adjacent registers, use realistic intervals and expose timeout or stale-state behaviour.
Keep asset identity in the hierarchy and put measured values, source time and quality in a governed payload.
A controlled path from register to topic.
Define register maps
Select function codes, addresses, data types and polling intervals for each device.
Decode and enrich
Convert raw registers, byte order and scaling into meaningful, contextual payloads.
Buffer and retry
Queue records locally during interruptions and resume delivery without losing sequence.
Publish to MQTT
Publish to a deliberate topic hierarchy with the required QoS and retained-message policy.
Built for operational reality.
Meaningful payloads
Translate raw register values into named fields with units, timestamps and device context.
Protocol separation
Keep Modbus polling inside the industrial zone while exposing a controlled MQTT interface to consumers.
Disciplined polling
Tune scan rates, grouping and timeouts to respect device capacity and serial network limits.
Resilient delivery
Store-and-forward behavior reduces gaps when the IT destination is temporarily unreachable.
Reusable topic model
Give applications a stable topic and payload convention instead of device-specific register knowledge.
Observable flow
Monitor connection state, queue depth and publish outcomes to make data delivery measurable.
Typical deployment boundary
OT side
- Explicit Modbus device and register allowlist
- Polling intervals matched to process needs
- Local queue sized for expected outages
IT / application side
- Authenticated and encrypted MQTT where supported
- Approved topic hierarchy, QoS and retention
- Monitoring for latency and failed publishes
Validate the flow with your own devices.
Start with one device, one register map and one measurable outcome.