Here are some Matlab .m files and a Matlab mex function (c language) used to convert Open Ephys data files to the Plexon .plx file, which can be opened by Plexon Offline-Sorter.
The two mex files ("ephys2plx_mex.mexmaci64" and "ephys2plx_mex.mexw64") are compiled with Matlab 2014a, if your Matlab version is older than 2014a, you may need to compile ephys2plx_mex.c
To compile the ephys2plx_mex.c file:
Line 1 in the ephys2plx.m file sets continuous data from which processor will be converted into .plx file. For example, the raw data from FPGA will be
ConProcessor = 'Sources/Rhythm FPGA'