The Frame4 spreadsheet is set up to allow the analysias of rigid-jointed 2D frames, but it is simple to use it for 2D truss analysis; simply either provide a moment release at each end of every member, or define every member with a second moment of area (I) sufficiently low that all bending moments will be negligible.  I have added a truss example to the download zip file.  The program has also had a minor upgrade to Ver 3.06.  Free download (including open source code) from Frame4.zip.

The truss example is taken from: http://richardson.eng.ua.edu/Former_Courses/CE_331_fa00/Notes/Truss_Design_Example.pdf

Truss Example – note that truss height should be 6 feet

The truss may either be specified with moment end releases at both ends of each member:

Or specify a very low I value for each member:

The results given in the example are shown below:

The axial load values from the spreadsheet are in good agreement:

Truss deflected shape:

Axial force in top and bottom chords: