Hi,

What you mean by non-legacy mode for arrays?

You can call MonitoredDataItem.setIndexRange before adding the MonitoredDataItem to Subscription (it should work after also, but then the server needs to change it’s own items so safer to do before). You need to know which indexies to monitor though.

Another question is how wise this is. If the array is small and fixed size, then it should be ok, but I wouldn’t do this for just the sake of knowing the index to item mapping instead of checking the new value for changes to specific indexies (Since each item creates server side items also, depending of course on server implementation but still).

– Bjarne

Hmm this is the first time I have heard the term legacy mode. However there is an ExposesItsArray ModelllingRule in UA which indicates that each array element should be exposed as a single value/node as a sub-node for the node having the array. If the VariableType has that rule, then there should be subnodes – otherwise not (or at least there is no guarantee)

“I am not sure that I understood well “If the array is small and fixed size, then it should be ok, but I wouldn’t do this for just the sake of knowing the index to item mapping instead of checking the new value for changes to specific indexies”.
Do I have another solution if I want to listen value changes of one array’s element?”
The answer to that depends on a number of factors:
Is the array fixed or changing size?
How big the array is?
How big is an individual value in the array (i.e. is it int32 or Structures)
Are you interested in every index or just some?
Do all indexies change at the same time or independent of each other?
Do you want to save server memory / processing power / network bandwith or code complexity?

But I would start e.g. by subscribing to the whole array and then checking onDataChange events if the indexies you are interested in have changed.