How to Use OPC Explorer for OPC UA & Classic Diagnostics

OPC Explorer Tutorial: Discover, Read, and Monitor Tags

Overview

OPC Explorer is a tool for connecting to OPC Classic (DA) and OPC UA servers to discover available servers and tags (items), read current values, and monitor changes. This tutorial covers discovering servers, browsing address spaces, reading values, and setting up subscriptions/monitors for real-time updates.

Prerequisites

• OPC Explorer installed (or a similar OPC client).
• Network access to the OPC server(s).
• Credentials or security certificates if the OPC server requires authentication.

1. Discover OPC Servers

1. Launch OPC Explorer.
2. Select discovery mode: choose OPC Classic (DA) or OPC UA depending on your server.
3. For OPC UA: enter server endpoint URL (e.g., opc.tcp://hostname:4840) or use network discovery.
4. For OPC Classic: browse the machine’s registered OPC servers or enter remote machine and enable DCOM/config as needed.
5. Authenticate if prompted (username/password or certificate).

2. Browse Address Space / Tags

1. Open the server connection.
2. Expand the server’s address space tree to view folders, objects, and tags/items.
3. Use filters or search to find tags by name or data type.
4. Inspect tag properties: NodeId/ItemID, data type, access rights, EU units, engineering limits, and timestamps.

3. Read Tag Values

1. Select one or more tags to read.
2. Perform a synchronous read to get current values, quality, and timestamp.
3. Interpret quality codes (Good, Bad, Uncertain) and timestamps to assess data reliability.
4. Convert or scale values if engineering units or scaling are provided.

4. Monitor / Subscribe to Tags

1. Create a subscription (monitor) for tags you want to track continuously.
2. Set sampling/heartbeat parameters: sampling interval (how often the server samples), publishing interval (how often notifications are sent), and queue size.
3. Choose monitoring mode: report-by-exception (only on change) or report-always.
4. View live updates in the client—watch value, status, and timestamp changes.
5. Log or export monitored data to CSV for analysis if supported.

5. Troubleshooting Tips

• OPC UA security: match client/server certificates and accepted security policies.
• OPC Classic DCOM: configure firewall, DCOM permissions, and correct user accounts for remote access.
• Quality issues: check server diagnostics and network latency; ensure proper sampling intervals.
• Missing tags: confirm namespaces and correct NodeId/ItemID formats.

6. Example Workflow (quick)

1. Connect to opc.tcp://plant-server:4840.
2. Browse to Devices → PLC1 → Variables.
3. Read Temperature sensor tag — observe value 72.4 °F, Quality=Good.
4. Subscribe to Temperature and Alarm tags with 500 ms sampling and report-on-change.
5. Export monitored data to CSV every hour.

7. Next Steps / Advanced

• Use scripting or API features (if available) to automate reads and logs.
• Configure historical reads if server supports history.
• Integrate OPC data into SCADA/IIoT platforms or MQTT bridges.