Linux Access To ControlLogix Data Tables

There are all kinds of ways for Microsoft Windows users to get data in and out of ControlLogix and CompactLogix PLCs. Rockwell sells a of tool called RSLinx. There are a bunch of different models and ways to use it.

There are also OPC Servers. OPC  uses native Microsoft technology to move data between applications. With that technology, one application can consume data generated by another application. If for example, you have a database collecting user names that accessed your stockroom. With this technology you could automatically transfer today’s access list to a Microsoft Word document. It’s relatively easy to get data from one MS application to another MS application.

But what about those of us that want to use Linux. How can a Linux application read and write data in a ControlLogix or CompactLogix? Or even access some of the Legacy PLCs like PLC5E or SLCs? Rockwell provides nothing for that.

In that case, you have to take a look at our Linux EtherNet/IP Tag Client software. This is ANSI C software that runs as a task in your Linux application. Your App simply opens a connection to the PLC, fills in a structure with the Tags (variable identification in the PLC) you want to read (or write) and sends that structure to the Tag Client Software. You get a callback when the operation is complete.

The beauty of this software is two fold. One, since it is ANSI C, it compiles using any IDE. And two, the API is so simple, it is really easy to use. Most customers get everything running in an hour or two.