Of all the protocols, OPC is most popular. “To understand why OPC is so popular, consider the example of printer drivers: Under MS-DOS, the developer of each application also had to develop a printer driver for every printer, one for an Epson FX-80, one for the HP LaserJet, and on and on. Microsoft solved the printer driver problem by incorporating printer support into the operating system. Today, printer drivers provided by printer manufacturers serve all applications.
In the industrial automation world, each company writes its HMI software and a proprietary driver for each industrial device (including every PLC brand). Rockwell wrote its HMI and a proprietary driver to each industrial device (including every PLC brand, not just its own) and so on. By adding the OPC specification to OLE technology in Windows, Microsoft is providing the infrastructure to solve the industrial device driver solution as well.
The image below depicts the 1:1 relationship between devices used in the analogy.
OPC simplifies protocol development by eliminating the need for an ICS vendor to produce an OPC client, foregoing the expense and effort of developing multiple protocols for their products.
Copyright: Cybersecurity & Infrastructure Security Agency (CISA)