To understand electronic camming, it helps to first know a bit about traditional mechanical cams.
A traditional mechanical cam setup works like this: the cam is typically a rotating part on a machine shaft that imparts motion onto a part called a follower. The cam itself can be irregularly shaped (not circular), oval shaped or have edge surface areas of varying height. The unique cam profile transfers this motion pattern to the follower, which can activate a switch or cause some other type of motion or action to occur.
Another way to put it is that a cam is essentially a motion profile, traditionally executed by mechanical means. The most familiar example may just be the cam and follower setup in a car engine. Here, a camshaft with lobes is spaced out on the shaft. As the shaft rotates the lobes move push rods that activate a rocker arm causing valves in the cylinder to open and close.
In electronic camming, the mechanical setup is replaced by electronics, usually with something called a cam profile function. These cam profiles are typically defined in a table as a set of x-y points. The biggest advantage of electronic camming is the ability to change motion profiles quickly and easily without having to make any mechanical adjustments or changes, as one would need to do in a traditional cam and follower setup. Electronic camming is accomplished with servomotors, actuators and drives and controllers with electronic gearing functions.