OPC UA is the closest thing industrial machines have to a common language. When a CNC control has an OPC UA server, software can read its state, counters and alarms without a driver written for that one control.
How OPC UA works
A machine runs an OPC UA server that publishes its data as a tree of named nodes — execution state, part counter, alarm list, and so on. Software connects as an OPC UA client, browses that tree, and reads or subscribes to the nodes it needs. The connection is usually opc.tcp://machine-ip:4840.
Because the data model is part of the standard, an OPC UA client doesn’t need to know the machine maker’s private protocol — only which nodes hold the values it wants.
Security modes
Security policy
- Options
- None, or signed and encrypted (e.g. Basic256Sha256)
- In practice
- Encrypted is the safer choice when the network is shared
User authentication
- Options
- Anonymous, or username and password
- In practice
- Some servers refuse anonymous reads of certain nodes
| Setting | Options | In practice |
|---|---|---|
| Security policy | None, or signed and encrypted (e.g. Basic256Sha256) | Encrypted is the safer choice when the network is shared |
| User authentication | Anonymous, or username and password | Some servers refuse anonymous reads of certain nodes |
Which modes a machine accepts is set on the machine’s own OPC UA server, so the client has to match it.
OPC UA on a CNC floor
On controls with an OPC UA server, ThingConnect connects as a client and reads execution state, part count, alarms and panel data, with either security policy and either login mode. Where a control has no OPC UA server, it connects another way — so a mixed floor still ends up on one screen. See the OPC UA integration page for details.