To use a sampling group as a data source for a historical trend, the following configuration specifications must be respected:


Items to be sampled

The sampled Items can be:


    1. Analog
    2. Digital


Note: you can also specify the Text Item type but in this case the system will always record the value 0.


Field to be sampled

It is possible to perform the sampling of only the  value field of the Item: even if you specify a different field, the system will still record in the log file the value of the Value field.


Historical files duration

The length of the log files must be set to "Daily"


Historical files format

 The format of the historical file registration must be set to "Internal."