Hi,
if you experience the same problem as I do after updating to El Capitan, then this might be a solution which helps you (as it does for me).
I use the MFP Samsung SCX-3200 (bought in 2010). Right after updating to El Capitan and adding the printer the driver only offers the function to print. No scan command button was provided within System Preferences > Printer & Scanner. If you visit Printer and scanner software available for download for your Mac you might notive, that your MFP is no longer supported with the scan function as officially confirmed by Apple.
Once contacted Samsung they advised to download the Samsung Printer Drivers v2.6 for OS X (for Mavericks, Mountain Lion, Lion and Snow Leopard). Now, the scan command button is available and it does work.
Maybe this is useful for printers from different manufacturer? Just browse the download area at Apple and download the right one.
Cheers
Nils
