To go further than just passing the variables:

You are not attempting to write the data at all. Assuming that $row = 0 and $col = 0, $format is defined, and they all are global variables (since they are not defined in excel_write), you are writing the string PLOTNAME to B1, and PAGEID to A2 on the worksheet PASS.

Do you get errors when running this, or does it run without complaining?