@Alien , @jacob.small ,
I solved it finaly
import clr
clr.AddReference('RevitAPI')
from Autodesk.Revit.DB import *
from System.Collections.Generic import *
clr.AddReference("RevitServices")
import RevitServices
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager
doc = DocumentManager.Instance.CurrentDBDocument
app = DocumentManager.Instance.CurrentUIApplication.Application
elements = UnwrapElement(IN[0])
result = []
x = 1
for i in elements:
for j in i.Parameters:
name = "Kommentar " + str(x)
t = Transaction(doc, name)
t.Start()
p = i.LookupParameter("Kommentare")
p.Set("X")
t.Commit()
x = x+1
OUT = "Done"
these are native Revit transactions instead of Dynamo transactions
KR
Andreas