In the layer properties and tab fields, I want to make all fields visible!
import arcpy
lyrXul = arcpy.mapping.Layer("Limits")
field_info = arcpy.Describe(lyrXul).fieldInfo
for i in range(0, field_info.count): field_info.setvisible(i, "VISIBLE")
arcpy.RefreshTOC()
arcpy.RefreshActiveView()