I am using ArcGIS 10.2 for Desktop.
I have a model which contains several branches, which branch should run is based on the results of an earlier stage in the model. If the first stage of the model returns a Null result Branch A should run otherwise Branch B should run. I check for a Null result by using the Get Raster Properties tool ALLNODATA type.
At the start of each branch I created a Calculate Value tool which checks the Get Raster Properties and returns a 1 or 0 based on if that branch should run, and then uses the output as a precondition for the rest of the branch.
This sort of works but once the tool has been run once the various outputs are pre-set and instead of running the "Get Raster Properties" and "Calculate Value" tools again ModelBuilder jumps over to run the branches which meet their preconditions.
Is there a way to set all the results of Calculate Value to 0 before each run of the model so that branches are not run until the Calculate Value tool has run?