Accessing Max/Min Property Errors

[smoothdurban]

Hello

I have run into a really wired situation but I am trying to access the max & min channel properties in a script and I get a null value as a result

So I am using the following function to gain access to the channel group in a for loop and it returns a null value after the first iteration of the loop.  However when I use the debugger, the function below return the correct values.

Data.Root.ActiveChannelGroup.Channels(i).Properties.Item("Maximum").Value

or

Data.Root.ActiveChannelGroup.Channels(i).Maximum

I am using 2017 SP1

Anyone else come across this?

[gsklyr · Accepted solution]

YesLINK TO THE ORIGINAL ARTICLE

[RussellSenior · Accepted solution]

Depending on how the data was brought in before you called this function, it's most likely that the characteristic values of the channel have yet to be calculated.  You have multiple options:

Call ChnCharacter(ChnArg1)  - This will calculate characteristics for one channel. 

Call ChnCharacterAll()  - Does it for all channels, could take a long time depending on how many channels. 

I personally like the CCh command. Function: CCh

ReturnValue = CCh(Channel,StatValueIndex)
Function: CCh

ChannelName	Specifies the data channel.
StatValueIndex	Specifies the index of the characteristic value to be calculated.
	Index Characteristic value 0 Mean value 1 Minimum 2 Maximum 3 Range 4 Total

[smoothdurban]

Awesome thanks for the input

I ended up using the ChnCharacter() function for each individual channel in an active channel group.

Call ChnCharacter(Data.Root.ActiveChannelGroup.Channels(i))

[AndreasK]

Some explanations:

1. I assume starting with 2017 the default for generating min max changed
   In older versions, the characteristics where automatically calculated on load
   Because it not always necessary, the default was changed
   Settings->DIadem Settings-> Panels->NAVIGATOR->Loading Behavior->Automatic calculate characteristic values
   or in Script
   

   ChnCharacteristicsUpdate="Automatic"
   

2. In your Debug Case Min Max is calculated because you selected the channel in Data Portal and preview was switched on.
   To show the preview the characteristics are calculated

3. ChnCharacter
   ChnCharacterAll

   is used to calculate them.
   You can also interactive right click in Data portal to calculate them