An integrator recently inquired about connecting FactorySQL to an OPC-HDA (historial data access) Server. A reasonable request. Hey, we're standardizing on OPC (DA) so why not? It seems reasonable that a historical data specification could bring some good to the table.
It turns out that OPC-HDA is another outdated COM based specification that was designed to standardize access to all of the different historian packages. Suppose you wanted a simple ActiveX graph or table back in the day. The idea is that it wouldn't have to know about the PLC. But wait, it still doesn't know how to poll the historical data. The user still needs to subscribe to tags, choose time ranges, etc. Sound like something that SQL's good at? Yeah, makes sense to use a standard interface. Plus, this many years later, all the vendors have jumped on the SQL bandwagon. And for good reason!
At this stage I can't even think of a practical way that FactorySQL could OPC-HDA that would make sense. Maybe if you needed to log from or write to an old HMI, but why? Logging works better from the PLC directly. Why would you ever need to write to an old HMI? It could only introducing unnecessary complexity and potential points of failure.
Aghh! Hurry, OPC-UA! We want web services! XML! Security models! NO MORE COM! Microsoft killed it so many years and major versions ago. Why can't industrial software follow suit!?!!? (I have my explanations, but will leave for another time)