OPC-UA Device Connections and Driver Setup in Ignition

Quick Answer

Ignition connects to PLCs, RTUs, and field instruments through its built-in OPC-UA server and a library of protocol drivers. Device connections are configured in the gateway web interface under Config > OPC-UA > Device Connections. Each connection specifies the driver type, device address, and polling parameters.

Supported Drivers

Ignition includes drivers for the most common industrial protocols:

• Allen-Bradley — EtherNet/IP for ControlLogix, CompactLogix, MicroLogix, and PLC-5/SLC (via PCCC)
• Siemens — S7 protocol for S7-300, S7-400, S7-1200, and S7-1500 CPUs
• Modbus — Modbus TCP and Modbus RTU/ASCII for flow meters, power meters, VFDs, and generic I/O
• DNP3 — DNP3 master for RTUs including Bristol FB300, Emerson ControlWave, and Schneider Electric RTAC
• BACnet — BACnet/IP for building automation and HVAC controllers
• MQTT — Sparkplug B via the Cirrus Link MQTT Engine module for IIoT edge data
• OPC-UA Client — Connect to third-party OPC-UA servers from other vendors

Configuring a Device Connection

1. Open Config > OPC-UA > Device Connections in the gateway web interface.
2. Click Create new Device Connection.
3. Select the appropriate driver (e.g., "Modbus TCP").
4. Enter the connection name, device hostname/IP, and port.
5. For Modbus: specify the Unit ID. For DNP3: set master and outstation addresses.
6. Select a scan class (default or custom) to define the polling rate.
7. Save and verify the connection status shows "Connected" in the device list.

Scan Classes

Scan classes define how frequently Ignition polls device registers. Best practices:

• Fast (100-500ms) — Use sparingly for safety-critical analogs. High scan rates increase network traffic and device CPU load.
• Normal (1-5s) — Appropriate for most process variables (temperatures, pressures, flows).
• Slow (10-60s) — Suitable for status discretes, equipment states, and non-critical data.
• Demand-driven — Leased scan classes that only poll when a tag is actively displayed on a client screen.

Troubleshooting Connections

Common issues and resolutions:

• Device shows "Disconnected" — Verify IP/port, check firewalls, and confirm the device is reachable via ping.
• Tags show Bad quality — Verify register addresses match the device configuration. Check for Modbus byte-order (big/little endian) mismatches.
• Slow response times — Reduce the number of tags or increase the scan class interval. Check if the device supports multi-register reads.