SAP business connector: Mapping only 3 characters


My mapping is working fine in business connector and Idocs are being generated successfully.

I want to know that if it is possible to retrieve only 3 characters from the source field and map it to the destination field?

I have a source field1 which is mapped on a destination field2.
The value of field1 is 94585/00/A
I want to map only the first 3 characters, i.e. 945, to field2.

Any suggestions??

Thanks and regards