QTreeWidget clicked signal

[faldzip]

What is the type of item and what is the type of "PLC"?
And in your code lnx is a local variable in different method so how do you want to reference it in this method?
I think you need to revise your C++ knowledge...
Why can't you use QTreeWidgetItem methods like for example text() to get know what item did you clicked?
You can event set your data with QTreeWidgetItem::setData() with Qt::UserRole while creating item to let you know what item it is.

QTreeWidgetItem lnx = new QTreeWidgetItem(ui->treeWidget);
lnx->setData(0, Qt::UserRole, "lnx");
 
// and check it:
if (item->data().toString() == "lnx")

QTreeWidgetItem lnx = new QTreeWidgetItem(ui->treeWidget);
lnx->setData(0, Qt::UserRole, "lnx");

// and check it:
if (item->data().toString() == "lnx")

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P.S. And use CODE tags for pasting code! Your code is already a mess in terms of formatting and without CODE tags it is even worse.