I am trying to grab data from a SLC 5/05 which we do not own the program to. OPC tag names are meaningless but we do have the electrical diagrams. Initially I added every tag that was available in the OPC Browser (3000+ tags). I then deleted all tags that were not physical IO which reduced my tag count to 93 although if you looked at the status for this device in the gateway, it said the tag count was ~250 and I had to use a 12 second scanclass to bring the load factor below 100%… I deleted the tags and the device then added only the 93 that I needed and all of a sudden I can use our default 1 second scanclass which gives me a load factor of 44%. Bit strange, just thought I would share.