If you keep up with our blog here at Nelson-Miller, you are probably well aware of the general concept of human machine interfaces (HMI). Consisting of an interface that allows the communication between a human operator and machine, HMIs are used in just about every industry and sector under the sun, including telecommunications, manufacturing, retail, food service, medical and aerospace (just to name a few). But how exactly does HMI differ from a user interface (UI)?
Computer Systems and Electronic Devices
While there are always exceptions to this rule, user interfaces are typically used to describe the interface of a computer, computer system, or similar electronic device. This is in stark contrast to human machine interfaces, which are typically used to describe the interface of a machine or industrial device. Again, there are exceptions to this rule, but you’ll usually find UIs being used in computers and electronic devices.
Locality to a Single Machine
Another distinguishing characteristic that separates human machine interfaces from user interfaces is locality. Human machine interfaces are usually local to a single machine or piece of equipment. The HMI may still be connected to a larger network for the purpose of reading data, but the actual interface usually only controls a single machine or piece of equipment. User interfaces, on the other hand, may control several different computers or electronic devices.
The actual design of a human machine interface usually consists of mechanical components and membrane keypads, whereas user interfaces are designed with an emphasis on digital controls. For instance, a user interface may support digital touchscreen commands via a computer. A human machine interface may feature a membrane keypad that’s connected to a machine display.
The Bottom Line…
The truth is that many people use the terms “human machine interface” and “user interface” interchangeably. As such, the differences between them have become narrower and narrower over the years. With that said, human machine interfaces are usually affixed to a single machine and have a focus on industrial equipment. User interfaces, on the other hand, may be connected to multiple devices and have a focus on computers.