Generally speaking artillery pieces as we know them were not common in pitched battles in medieval warfare. They were time consuming to make and difficult to haul into battle, therefore they were not the preferred method of waging war, especially since given their difficulty to use and ease of destruction the difficulty in hauling them was questionable.

The majority of medieval conflicts were satisfied through raiding and sieges, with the pitched battles being in the minority due to their high risk and difficulty in achieving. What I mean by this is castles were frequent enough and so often the objective that commanders almost always had the option of opting not to go to battle. Mix in the relatively temporary nature of medieval armies and you did not really have the time or the inclination to try to field thousands of men on the field of battle and throw everything to the wind.

When it came to catapults, trebuchets, etc., they were relatively simple devices that could be constructed at the siege. If you pre-assembled them your entire army slows down trying to accommodate for them, then you must defend them while they are erected on the battlefield. Then you must defend them while they are torn down, delaying your chase.