Connections
Define communication channels to OT devices using industrial protocols. Each connection feeds the tag polling engine and appears as a tile in the connection view.
The Connections page is the starting point of every project. A connection defines how the gateway communicates with one physical device or data source. Without at least one connection, the Tag Database has no data to work with.
The page opens as a tile view. Each configured connection appears as a card showing its name, protocol, and live status. On a new project, only the Add Connection tile is visible.
Supported protocols
The most widely used industrial protocol. Connects to PLCs, energy meters, variable-speed drives, and sensors over Ethernet. Modbus TCP uses a reliable connection-oriented transport; Modbus UDP is faster and suits time-critical or simple read-only applications.
Connects to an OPC UA server exposed by a PLC or SCADA system. Provides a browseable address space for data point discovery. Supports certificate-based security and encrypted sessions.
Native driver for Allen-Bradley and Rockwell Automation PLCs (ControlLogix, CompactLogix, MicroLogix). Communicates directly with the PLC’s tag database using CIP over Ethernet.
Optimized driver for Siemens S7-1200 and S7-1500 PLCs using their built-in OPC UA server. Supports TLS encryption and certificate-based authentication.
Subscribes to topics from an external MQTT broker. The gateway acts as an MQTT client — useful for receiving data from IoT edge devices, cloud feeds, or other MQTT-enabled systems.
This is the inbound MQTT connection — distinct from the built-in MQTT Broker under Settings, which publishes gateway data outward.
Polls HTTP/REST endpoints on a configurable interval. Suitable for web services, cloud APIs, or any device that exposes data over HTTP.
Reads values from relational databases — MySQL, PostgreSQL, Microsoft SQL Server, and SQLite. Define SQL queries whose results map to tag values.
Virtual registers stored in the gateway’s own memory — no physical device required. Global Memory persists between restarts; Local Memory resets on restart.
Adding a connection
Click the Add Connection tile to open the connection setup dialog.
Choose the protocol that matches your device. The available parameter fields update automatically based on your selection.
Enter the required details — IP address, port, unit ID, polling interval, and authentication as needed. The exact fields depend on the chosen protocol.
Use a name that identifies the device and its location (e.g., Compressor_PLC, Energy_Meter_Hall_A). This name appears on the tile and in the Tag Database.
Click Save — the gateway begins polling immediately. Check the tile’s status indicator to confirm the connection comes online.
Connection status
Each tile shows a live status indicator. Online means the gateway is successfully exchanging data with the device. Offline means the device is not reachable — check network connectivity and device power. Error means the device responded but the request failed — review the connection’s IP address, port, unit ID, and protocol-specific parameters.
Managing connections
From any connection tile you can edit, duplicate, or delete the connection. Duplicating is useful when adding multiple devices with identical protocol settings and only different IP addresses.
All tags that belong to a deleted connection are permanently removed from the Tag Database. Document or export your tag list before deleting a connection.
Database
The SQL database communication protocol enables the gateway to read values from relational databases by establishing a client-to-server connection. DataTalk supports MySQL, PostgreSQL, Microsoft SQL Server, and SQLite. Define SQL queries whose results map directly to tag values — useful for pulling reference data, setpoints, or production records from an existing enterprise database.
EtherNet/IP
Ethernet/IP is a widely used communication protocol for industrial automation, enabling seamless data exchange between PLCs and SCADA systems. It operates over standard Ethernet using CIP (Common Industrial Protocol), providing real-time data exchange, device configuration, and control. The gateway communicates natively with Allen-Bradley and Rockwell Automation PLCs (ControlLogix, CompactLogix, MicroLogix), allowing online tag import from the PLC’s tag database as well as import from .L5X project export files.
Learn more about EtherNet/IP →
Global / Local Memory
Global / Local Memory provides virtual registers stored entirely within the gateway’s own memory — no physical PLC hardware required. It simulates various data types, supports control logic testing, and enables cross-tag communication within a project. Use cases include auxiliary calculation variables, state sharing between HMI clients, and demo or test projects where no physical device is available.
Learn more about Global / Local Memory →
MQTT
MQTT (Message Queuing Telemetry Transport) is a lightweight communication protocol designed for IoT and machine-to-machine applications. In DataTalk, the MQTT driver acts as a client that subscribes to topics from an external MQTT broker, following a publish/subscribe model.
In the publish/subscribe model, devices publish messages to a named topic and other devices subscribe to receive those messages — decoupling sender and receiver for scalable communication. In a device-to-device model, communication occurs directly between individually identified devices.
This is the inbound MQTT connection for receiving data from IoT edge devices, cloud feeds, or other MQTT-enabled systems — distinct from the built-in MQTT Broker under Settings, which publishes gateway data outward.
OPC UA
OPC UA (Unified Architecture) is a communication standard developed by the OPC Foundation, succeeding the legacy OLE for Process Control standard. An OPC server acts as an intermediary for all data access — all requests are mediated by the OPC server’s configuration.
Security — Secure message interchange through modern cryptography, including TLS encryption and certificate-based authentication, protecting data in transit.
Scalability — The OPC server can communicate with infrastructure from different vendors, promoting interoperability across diverse industrial automation systems.
Siemens OPC UA
Siemens S7-1200 and S7-1500 PLCs include an integrated OPC UA server that enables standardized data exchange without additional middleware. The Siemens OPC UA driver in DataTalk is optimized specifically for these controllers.
Secure communication — TLS encryption and certificate-based authentication protect all data in transit.
Interoperability — Standardized architecture supports multiple clients from different vendors simultaneously.
Configurable access control — Read and write permissions are managed at the OPC UA server level, controlling which data points each client can access.
Learn more about Siemens OPC UA →
REST API
The REST API driver polls HTTP/REST endpoints on a configurable interval using standard HTTP methods. Use it for web services, cloud APIs, or any device that exposes data over HTTP. Configure custom headers and authentication as required by the target endpoint.
Modbus TCP/UDP
Modbus TCP and Modbus UDP are Ethernet-based variants of the Modbus protocol. Modbus TCP communicates over TCP/IP, providing reliable connection-oriented messaging for PLCs, energy meters, variable-speed drives, and sensors. Modbus UDP uses a faster connectionless approach suited for time-critical or simple read-only applications. Both variants use the standard Modbus addressing model — holding registers, input registers, coils, and discrete inputs — identified by function code and register number.