You would need a DSA-Board or a S-Series board to program a lock in amplifier.
Because the M_series boards are multiplexing all there channels to one A/D converter, it is not possible to program a lock in amplifier with a M-Series device. You need a board that can sample multiple channels simultaneous, like a S_Series board or a DSA device.
Check this link out for more details:
http://zone.ni.com/devzone/conceptd.nsf/webmain/3b2936e1afe39ac286256c2f00746422
