Quick start: Modbus to OPC UA

In the left panel, expand Data Interface and double-click Connections. The tile view opens.

Click the Add Connection tile. A dialog asks for a name — enter a descriptive identifier, e.g. Energy_Meter_Hall_A, and click Set.

The connection form opens with a Type dropdown. Open it and choose Modbus from the list.

After selecting Modbus, the form shows the connection fields. Enter the details for your device:

• IP Address — the device’s IP address on your network, e.g. 192.168.1.100
• Port — 502 (standard Modbus TCP port)
• Default Device ID — the Modbus slave address of the device, typically 1; check your device manual if unsure
• Transport — TCP
• Refresh [ms] — how often the gateway reads all tags from this device, e.g. 1000

Click Save. The connection tile appears in the view. A green status indicator means the gateway successfully reached the device. If it stays red, check the IP address, port, and that the device is powered and on the same network.

In the left panel, double-click Tag Database under Data Interface → Tags.

The tag grid shows your connections as expandable rows. Click the ▶ arrow next to Energy_Meter_Hall_A to expand it.

Click the + icon at the end of the Energy_Meter_Hall_A row to add a tag under that connection. A new inline row appears for editing.

Fill in the columns for the first tag:

Tag — Total_Energy_kWh — internal identifier, no spaces; used in formulas and cross-references.

Address — H:0 — holding register 0 in Modbus; check your device register map for the correct number.

Type — FLOAT — must match the data type the device transmits; a wrong type produces garbage values.

Access — R — read-only for sensor inputs; set RW only when operators need to write back to the device.

Label / Note — Total energy consumption — human-readable description shown to operators in HMI views.

Instrument — EM-101 — optional P&ID reference; free-text field for cross-referencing physical documentation.

Scale — 0.1 — use when the device sends an integer scaled by a factor (e.g. raw value 1234 → displayed as 123.4 kWh). Leave at 1 if the device already sends engineering values.

Unit — kWh — engineering unit displayed alongside the value.

Log — default — assigns the tag to the default log group so its history is recorded.

Press Enter or click away to confirm the row.

Repeat for each register you want to read. Common energy meter tags:

Active_Power_W — address H:2, type FLOAT, unit W — instantaneous active power draw.

Voltage_L1_V — address H:10, type UINT16, unit V — phase L1 voltage.

Current_L1_A — address H:12, type FLOAT, unit A — phase L1 current.

Power_Factor — address H:20, type FLOAT, no unit — dimensionless value between 0 and 1.

Frequency_Hz — address H:22, type FLOAT, unit Hz — grid frequency.

Click the Read Values tab at the top of the Tag Database page. Within one polling interval, the Value column should fill in with numbers from the device. If a value shows -- or an error, check the register address and data type against the device manual.

In the left panel, expand Settings and double-click Data Servers.

Click the OPC UA tab at the top of the Data Servers page.

Check the Enable checkbox. The OPC UA Server starts immediately on port 4840 (the standard OPC UA port).

By default, Anonymous access is enabled — any OPC UA client on the network can connect without credentials. For production use, also enable Use User Name and Password and disable Anonymous:

• Check Use User Name and Password — clients must authenticate with a DataTalk user account
• Uncheck Anonymous once you have confirmed clients can connect with credentials

Click Save. The OPC UA Server is now live.