Caroline,
Yes, the 7831R is commonly used to generate a SPI interface. See the following article for a description of SPI with CompactRIO, another NI RIO target. The interface information applied directly to the 7831R as well
http://zone.ni.com/devzone/conceptd.nsf/webmain/d3955e49973bcdbf86256f290077a761?OpenDocument
Chris