Getting PLC data out: OPC UA servers, gateways and MQTT
By PlantWired · Last reviewed October 16, 2026
Before any SCADA, MES or analytics project, data has to leave the PLCs. The usual options are an OPC server/gateway that speaks many PLC drivers, an edge platform, or publishing directly to MQTT.
The right choice depends mostly on which PLC families you have, how many sites, and whether the destination is on-premises or cloud.
Here are the connectivity and edge tools in our directory with what each is listed as connecting to.
OPC servers & gateways
Driver libraries that expose PLC data as OPC UA (and often MQTT).
- Cirrus Link MQTT Modules · Cirrus Link · Per-module license
MQTT/Sparkplug B modules for Ignition that enable report-by-exception data movement between edge and enterprise.
Listed with: Ignition, Ignition Edge, HiveMQ, AWS IoT SiteWise, Azure IoT
- Kepware KEPServerEX · PTC · Per-driver/suite license
Driver-based OPC UA/DA server with a large library of PLC and device protocols, used as a universal translator on the plant floor.
Listed with: Ignition, AVEVA PI System, ThingWorx, SIMATIC WinCC, FactoryTalk View, Canary Historian, Proficy iFIX
- HiveMQ · HiveMQ · Open-source + enterprise tiers
Enterprise MQTT broker frequently used as the backbone of a Unified Namespace architecture.
Listed with: Ignition, Cirrus Link MQTT Modules, Litmus Edge, AWS IoT SiteWise, Azure IoT
- Litmus Edge · Litmus · Subscription
Industrial edge platform for collecting, normalizing and forwarding machine data.
Listed with: HiveMQ, Ignition, Azure IoT, AWS IoT SiteWise
- Matrikon OPC UA Tunneller · Honeywell · Per-product license
OPC connectivity products, including classic-to-UA tunnelling, from Honeywell's Matrikon line.
- Softing dataFEED · Softing · Per-product license
Family of OPC UA and MQTT gateways for reading data from Siemens and Rockwell PLCs.
- Node-RED · OpenJS Foundation · Free (open source)
Open-source flow-based tool for wiring protocols, APIs and devices together; common at the edge.
Listed with: HiveMQ, EMQX
- EMQX · EMQ Technologies · Open-source + enterprise tiers
High-throughput MQTT broker available as open source and enterprise editions.
Listed with: Node-RED
- Eclipse Mosquitto · Eclipse Foundation · Free (open source)
Lightweight open-source MQTT broker, often the first broker in a pilot.
Listed with: Node-RED
Edge platforms
Collect, normalize and forward data, sometimes running apps at the edge.
- Ignition Edge · Inductive Automation · Per-device license
Lightweight Ignition edition for field devices and panels that collects and forwards data to a central system.
Listed with: Ignition, Cirrus Link MQTT Modules, HiveMQ
- Siemens Industrial Edge · Siemens · Device + app subscriptions
Edge computing platform for running containerized apps next to SIMATIC automation.
Listed with: SIMATIC WinCC, Insights Hub, Azure IoT
- AVEVA Edge · AVEVA · License
Compact HMI/SCADA for machine builders and embedded panels (InduSoft lineage).
Listed with: AVEVA PI System, AVEVA System Platform
- FlowFuse · FlowFuse · Free tier + subscription
Managed platform for running, securing and scaling many Node-RED instances in industrial settings.
Listed with: Node-RED
MQTT brokers
Where edge devices publish when you go the MQTT/UNS route.
Questions to answer before you choose
- Which PLC families and protocols must be supported?
- Do you need classic OPC DA tunnelling to OPC UA?
- How will you secure and manage gateways across sites?
- Is the destination a SCADA, a historian, or the cloud?
Sources
Tool descriptions, pricing models and integration links come from the PlantWired directory, compiled from each vendor's public website (linked on every tool page). See our methodology. Not a recommendation; verify with vendors.
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