There a couple of supported plugins, developed by our partner IT-Novum

• SAP ERP Table Input
• SAP BW/ERP RFC Executor
• SAP BW DSO Input
• SAP BW Infocube Input

For more details see https://it-novum.com/en/big-data-analytics/pentaho-sap-connector/

Further options for loading data from SAP including SAP ECC (ERP), SAP BW (SAP BI), SAP CRM, HANA

Most users know the file based option to create a text file (prepared by ABAP programms) and load this data with the CSV Input step, but there are other ways:

• You can use the Webservices Lookup step and load queries or infoproviders via XML for Analysis. This does not work out-of-the-box and needs special customizing and writing special transformations, SAP BI may be needed. The OLAP Input step simplifies this and was tested successfully.
• Another option is using Open Hub Service within a SAP BI environment: "BI objects such as InfoCubes, DataStore objects, or InfoObjects (attributes or texts) can function as open hub data sources. You can select database tables or flat files as open hub destinations. Both a full and a delta mode are also available as the extraction mode."
• Further information about accessing SAP CRM (e.g. the data model) can be found over here: http://wiki.sdn.sap.com/wiki/display/CRM/CRM+Developer%27s+Knowledge+Corner 
• In general SAP recommends using Enterprise Services aka web services to access the functionality remotely: http://esworkplace.sap.com/
• You may access the SAP tables direct in the database, but there are security considerations and there may be unknown side effects not going via the application level.
• The SAP HANA database has been added to the list of available database connections in Pentaho PDI 5.4. See the JDBC Driver Reference and Set Up a Database Connection topics in the Pentaho Help site for more detailed information. Pentaho PDI 6.0 added support for the SAP Hana Bulk Loader.
• And please sees the supported plugins by our partner IT-Novum (section above) for loading data from SAP ERP, DSO, Infocube and others.

Transferring data to SAP BW (SAP BI)

There are two main options to load data to SAP BW:

1. Create a flat file (fixed or CSV file) and follow the procedures documented in Data Transfer from Flat Files (suitable for larger amounts of data).
2. Create a XML file and use a SOAP service via the HTTP step and follow the procedures documented in SOAP-Based Transfer of Data (suitable for regularly supplying SAP BW with limited amounts of data for each call). see also XML DataSource (BW DataSource with SOAP Connection)