Applies To:
  • CitectSCADA 6.XX
  • CitectHMI 6.XX

When I run TrnGetTable() for a certain number of samples it returns the trend data into the specified array. When I choose a greater number of samples it fills the array with zeros.

The function TrnGetTable() can only request a maximum or 4000 samples at any one time. This limit is in place to make sure that large requests don't "swamp" the trend server, possibly using up all of it's memory.

You can make multiple smaller requests or to allow the function to request more than 4000 samples you can increase the citect.ini parameter [Trend]MaxRequestLength.


The maximum trend sample requests allowed per trend in one go.

Allowable Values: 1 to 100000000

Default Value: 4000 

TrnGetTable, sample, samples, period, periods, maximum, max