3. Synchronous and asynchronous approaches

If we continue our study of the level control application shown in figure 1 , we now need to specify the hardware architecture of the control system. There are a number of possibilities, even in this simple example, depending on the functions to be transferred to the (level) sensor and the (control valve) actuator.

Let's choose the most conventional solution here: sensors and actuators without remote intelligence, a driver station consisting of a single-processor ECU equipped with the I/O interfaces appropriate to the application, and an operator console. This is the solution illustrated in figure