Parameter passing between ERP field (e.g. customer number) and Design Studio Application

Hi experts,

we would like to use the parameter passing between a ERP field (e.g. customer number) and a Design Studio Application with a BEx Variable (e.g. Customer -> 0S_CUSTO) to call the DS Application with a specific filter value (e.g. customer number).

Any experencies how to concatenate the URL with the relevant parameters correctly?

If I exceute the Design Studio Application on SAP NetWeaver Portal mode, the standard url looks like as following...

How I should add the name of the BEx variable (e.g. var_name_1=0S_CUSTO) and the ERP field with the relevant filter information (e.g. @KUNNR@)?

Thanks in advance and best regards,

Michael