When I increase the ReadData or WriteData array sizes in my program, all of the configuration parameter values go to 0.

When controller tag array sizes are changed in the ControlLogix platform, RSLogix5000 re-initializes all of the tags within that data type. This sets all values to 0 in all tags within that group. Before changing any controller tag array sizes, the user should record all configuration parameter values, and re-enter those values after the array size has been changed.