The encoder inputs of the 7344 are ground referenced. So the answer is yes, you can use a single ended encoder with a 7344 controller. Signal connection should be straight forward.
If you are using a UMI-7764 for signal connections please refer to the "Encoder Terminal Block" section (page 15) of the UMI User Guide. There are drawings for the signal connections for single ended and differential encoders.
For the case that you don't have the user guide of the UMI-7764 please download it from this link:
http://digital.ni.com/manuals.nsf/websearch/AC6FAA69218C9624862567BD0061DDAC?OpenDocument&node=132100_US
Best regards,
Jochen Klier
Applications Engineering Group Leader
National Instruments Germany GmbH
