I misunderstood when you said you would use a Friedman procedure. The Friedman test is a two-way ANOVA, the Kruskal-Wallis or Wilcoxon test is a one-way ANOVA.
Your response should be continuous and your independent variable is ordinal or nominal. Since you do have ranks, I agree that the modeling type could be considered as ordinal, but to get the proper test, make it continuous. Your results will still be correct.
Think of it this way. Suppose your data looked like this (only a few observations for a small example):
Group 1: 83.6, 92.1, 76.2, 84.9
Group 2: 63.2, 79.3, 77.8, 82.0
Now form the ranks:
Group 1: 6, 8, 2, 7
Group 2: 1, 4, 3, 5
Now pretend the ranks are continuous and is your response and go through the steps again. You end up with the same ranks. Therefore, JMP will create ranks based on your ranked data (essentially, unchanging the response) and performing the test. Correct methodology and correct results even though you do not have the "true continuous" response.
Dan Obermiller