Applies To:
  • CitectSCADA 3.00 4.00

Why are my event trend files 5 to 6 times larger than my periodic trends when my Sample times and Period are the same. 

Event trend files log based on a trigger. Every time the trigger expression becomes TRUE, it logs one sample. Whereas periodic trend files have a header, then 2 bytes for every sample (see Q1334), event trends have the same sort of header but have 4 bytes for the expression it is trending, 4 bytes for the date/time and 4 bytes for milliseconds for every sample. So the resulting file will be roughly 6 times larger.