Discrete, analog and motion control functionality are often needed for machine, skid mounted process equipment and robot builders for the systems they build. This meant figuring out how to integrate several task specific controllers to get the job done, until recently. To perform all those control functions within one integrated platform, there are hybrid controllers available now.
To define hybrid controllers as capable, there are three general types of control, discrete (on/off), analog and motion. The hybrid controller is different with special-purpose controllers that they only perform one type of control. Special purpose controllers including small PLCs (discrete), single or multi loop PID controllers (analog), and motion only controllers.
When all controllers were special-purpose, many machine builders recall a time not long ago. PLC was not invented until well in the 1960s, and vendors spent decades refining and perfecting on/off control with PLCs. The most PLC vendors began to add process control and motion control function to PLC was not until the 1990s. Before PLCs, single and multi loop controllers were used, but the discrete control function’s addition did not follow until the 1990s.
Discrete control was added by motion control vendors and some motion controllers now can also execute analog process control functions. As the dedication motion controllers have been used as long as loop controllers and the addition control functions was a fairly phenomenon.