Exploring common HMI controls

All systems need some way for the operator to send input signals and receive feedback. For purely physical systems, these input devices are things such as switches, buttons, and so on for the inputs while things such as LEDs and gauges are used for the outputs. However, this can be costly and, in the modern computer-driven world, unnecessary as we can simply program in our controls. As such, the remainder of this section will explore software-based controls.

Flip switches

As we all learned in high school, a switch causes a break in a circuit that will essentially cause the flow of electricity to stop when it reaches the switch. In other words, with the switch closed, the electricity is free to flow in the circuit, which will cause the equivalent of a TRUE condition. If the switch is open, the electricity will not be allowed to flow throughout the circuit, which will cause a FALSE condition. In terms of HMIs, a switch can be thought of in a similar...