I have a spreadsheet I wish to send the values of some cells to a program which is run on a different operating system, but on the same computer. I have to use Exceed to open a X server to run this Unix program which calculates thermodynamic properties. I have to currently manually plug in the values in my spreadsheet into the program and then run the program which gives me new values for which I manually plug back into Excel. The cells in my Excel spreadsheet have circular references which iterate to a value up to a certain tolerance. I would really like it if there was some way to continually export the cells values to the Unix program until the iteratation is complete (this can take up to 30 iterations aka 30 times of manually swapping between Excel and this Unix program plugging in multiple cells values and back again). I am proficient in VBA so I know how to write and use VBA programs/macros if this helps. The Unix program is written in Fortran 77. Thanks for any help!