After putting the three state chips on the outside it stopped freezing at 198, it now stops at 254, but I think I can fix it with a pulse to make half of it update and then the other half at the next simulation tick. Also, if the simulation is in a different thread then it may be that it is hitting a stack overflow error and that is why it is freezing while the rest of the application remains fine. Also no worries with the late reply, it's all good