Applies To:
  • CitectSCADA 5.xx

I place a single tag of type Array (long) on a page and find that it will not display. What is the cause of this? 

In the above example, the problem could have resulted because the tag had been directed at an integer area of a data block. At runtime, the Citect driver would use the Applicom API Readdifdword function to request one word at the selected address when the page was displayed. The profibus FMS protocol interprets this request as a request for one of the underlying datatypes at that address ie one integer. As a LONG is two integers in width, an error would result. This example highlights the need use the Citect driver datatypes that match the device internal data block structure.