Variant Configuration Procedure - convert numeric into char

Hello SDN!

I am using CU02 procedures and now I want to convert a numeric value into a character value.

What I have tried so far:

$self.machno = $self.maschnr.

But the syntax check brings up and error:

E28075 Character string required in inverted commas

E28024 Syntax error in simple action/procedure

Details of the error

E28049 Characteristic MACHNO is not restrictable

E28049 Characteristic MACHNO is not restrictable

E28054 MACHNO is not a multiple-value characteristic

E28054 MACHNO is not a multiple-value characteristic

E28075 Character string required in inverted commas

E28039 Alphanumeric expression required

What can I do? I cannot find any help or information what kind of commands I could use.

E.g. the ABAP command write is not working.

Please help me!

Thanks

Matthias