Hi @f_yilmaz_82. The code I posted was just to help you see all the hidden code contents behind the note, to give you a better idea of how Inventor keeps the text shown accurate and linked to the model. Replacing all that with simple, non-coded text will break that link, and just won't work out as you are hoping for. First of all, I see in your code that you are setting the BendNote.Text to a empty String, before testing its contents, which defeats the purpose and won't work, because there is nothing left to check. Next, simply attempting to replace that angle value in the BendNote.Text with the same bend angle, plus some extra text won't work either, because all the formatting code still exists within the BendNote.FormattedBendNote, so you end up with different results than you are expecting. You need to make the changes within the BendNote.FormattedBendNote, for them to turn out the way you want, which is going to be a bit trickier to do, due to the XML tags involved.
I created a simple example to test this functionality on. I have small sheet metal part with a 90 degree bend in it, that I created a flat pattern view of in a drawing. I added a default bend note to its one bend linen. It reads "UP 90° R.13". If I try to just replace the "90°" within the BendNote.Text, I end up with nearly twice as much text as I started with...essentially the original text, followed by the modified text. So, since I know I need to be dealing with the BendNote.FormattedBendNote contents, and I know what text that holds due to the first code I posted, I know what to search for.
The text within that is as follows:
"<BendDirection/> <BendAngle Precision='2' UpperTolerance='0.000000' LowerTolerance='0.000000' ToleranceType='kSymmetricTolerance' TolerancePrecision='2'></BendAngle> R<BendRadius Precision='2' AlternatePrecision='2' UpperTolerance='0.000000' LowerTolerance='0.000000' ToleranceType='kSymmetricTolerance' TolerancePrecision='2' ToleranceAlternatePrecision='2'></BendRadius>"
We can tell that there is a "<BendAngle" opener tag, then later a "</BendAngle>" closing tag, all of which represents the "90°" part of the main Text. And we know we want to insert our extra text after that, but before the rest of it. So, here is an iLogic rule I created to do that, and it is working for my example.
oDDoc = ThisDrawing.Document
oSheet = oDDoc.ActiveSheet
oBNote = oSheet.DrawingNotes.BendNotes.Item(1)
If oBNote.Text.Contains("90°") Then
oTerm = "</BendAngle>" 'at the end of the bend angle note
oFBN = oBNote.FormattedBendNote
'find the position of that text within the overall text
oPos = InStrRev(oFBN, oTerm)
oBNote.FormattedBendNote = oFBN.Insert(oPos + Len(oTerm) -1, " (OPEN) ")
End If
This finds the position of the closing tag for the bend angle, so we can use that to help us know where to insert our extra text. Then we set the new value of oBNote.FormattedBendNote to the new value we are inserting our extra text into. Within that line, you see that I am also getting the length (# of characters) of the search term too, so that it will be inserted after the end of where that search term is found, instead of at the beginning of it. The bend note in my drawing view now shows "UP 90°±.00° (OPEN) R.13±.00". That's because, for some reason it toggled the settings within that note, and turned on the tolerances, that were previously not showing. If I manually double click on that bend note, I get the small dialog labeled "Edit Bend Note" as seen here. If I click on the Precision and Tolerance button, it will open up another small dialog labeled "Precision and Tolerance" as also seen here.

If I click on the Precision and Tolerance button, it will open up another small dialog labeled "Precision and Tolerance" as also seen here.

I had to uncheck both of those check boxes to the right, then check the box by "Use Global Precision", then click OK. Then my bend note looked as I wanted it to ("UP 90° (OPEN) R.13"). Since I did not have any of that turned on to start with, I don't know why those settings were turned on afterwards, when all I did was inject that little bit of extra text in the middle of what was already there, but that's what happened in my case.
Wesley Crihfield

(Not an Autodesk Employee)