Cam we talk?

Beyond point-to-point moves, there is a broad range of motion applications that require repetitive motion, indexed by a master timer or -encoder. Such applications fall under the category of electronic cams, which includes the related but simpler approach known as electronic gearing.

Cams typically also use downloadable tables. In this case the tables are used to define a target position for each location of the master encoder or each tick of the master clock. The user can download a trapezoidal profile, an s-curve profile, or more commonly, a custom profile that replicates the function of a specially-shaped mechanical cam.

There are a number of ways to specify the relationship between the master clock and the controlled axis. The most common is to define the number of encoder counts that make up a 360 deg 'rotation' of the master encoder, and then allow one or more output points to be defined at each degree position of the table. When executing the table, after reading the last location of the table the motion controller will 'wrap' back, and restart from the first. Because of this, the beginning and ending position targets must be the same, or very similar, to avoid a discontinuous jump in motion.

Parabolic profile