Reject false values from trends log

[p_xatzi]

Hi all,

I have set Trends for pH and Cl in a water disinfection system. Unfortunately, for some reason signal is lost some times (hope to figure out why) and the result is to receive zero values or almost zero. I have a controller where physical signals (4-20mA) for pH and CL connect and then communication is done through modbus TCP. So, when controller reads zero, LM reads also that value.

The main problem for this is that these false values lower the mean value for the specified period.

Is there any way to reject these values. Let' s say to set a filter for the values that will be logged (e.g. greater than 5.0 for pH and greater than 0.1 for CL?

Is it possible to edit the data afterwards by a manual or automated way so as to get correct results?

Thanks in advance

[admin]

Create new object with the same datatype and map the Modbus register to this object. Then add an event script to this object that will check if the value is big enough and will update the original object if it is. Change 1/1/1 to the group address that is mapped to the trend log.

Code:

value = event.getvalue()
if value >= 5 then
  grp.checkupdate('1/1/1', value)
end

Trend logs cannot be edited.

[p_xatzi]

Create new object with the same datatype and map the Modbus register to this object. Then add an event script to this object that will check if the value is big enough and will update the original object if it is. Change 1/1/1 to the group address that is mapped to the trend log.

Code:

value = event.getvalue()
if value >= 5 then
  grp.checkupdate('1/1/1', value)
end

Trend logs cannot be edited.

Thanks for the reply!