[Trisquel-users] Free Software Alternative to : Software Toolbox Top Server?

[mdunivan]

Is there a GNU Project or GLP'ed alternative to Software Toolbox's Top Server  
(an OPC Server)?

Top Server OPC & I/O: http://toolboxopc.com/
What is OPC (The Interoperability Standard for Industrial Automation)?  
https://opcfoundation.org/about/what-is-opc/

There are 2 standards: OPC Classic  
https://opcfoundation.org/about/opc-technologies/opc-classic/

And Unified Architecture: https://opcfoundation.org/about/what-is-opc/