Thanks for taking the time to look. If it works it will allow me to compensate that currently it is not possible to create an array of UDTs in another UDT : array-of-udt-inside-another-udt
In the parent UDT I have to recreate a child UDT per instance but everyone uses the same source with the PLC.
PLC configuration :
It works fine for reading but not for writing.
Otherwise I would have to create one source tag per child but that multiplies the number of communications by the same amount!!!
Especially since I keep the source tag of the parent because it's much faster to loop in the Json of it than to do a "system.tag.readBlocking()" on the parent tag. The time ranges from a few milliseconds to several seconds.