Industrial Monitor Types: What is the difference?

CRT, HMI, Operator Interface, Industrial Computers

CRT, HMI, Operator Interface, and Indusrtial Computer Explained

Many terms exist for seemingly similar pieces of servo system equipment: Operator interface, HMI, CRT Monitor, Industrial Computer. So, what do the different terms mean, and which servo component terms have similar or different meanings?

Operator Interface

Operator interface refers to a control system a person uses to communicate with the multiple linked servo system components. Operator interfaces include both hardware and software allowing a person to interact with the machinery. Operator interfaces are manufacturer specific, which requires you to use the same manufacturer for all servo equipment parts.


HMI stands for Human Machine Interface. Like an operator interface, an HMI is made up of both software and hardware and allows a user to communicate with the machinery; however, HMIs are part of one machine or a piece of equipment, whereas operator interfaces are part of linked servo equipment. The user communicating with the machinery can manipulate the machines system and view the effects of the users’ manipulations. The HMI is manufacturer specific to the machinery and servo system you are using.

CRT Monitor

Cathode Ray Tube (CRT) monitors are used to display faults, positioning, and machine status. Some CRT monitors do work as Operator Interfaces; for example, Fanuc’s CRT monitors are made to both display and allow a person to communicate with their machinery. Cathode Ray Tube refers to the glass tube screen of the monitor; today CRT monitors are outdated and inefficient compared to LCD monitors; however, CRT monitors can easily be updated to LCD monitors through LCD retrofitting. CRT monitors are manufacturer specific to the servo system and machinery you are using.

Industrial Computer

An industrial computer is a programming terminal; it is used to program the machinery. The industrial computer can be used to change the settings to pick up different faults, and it can be used to save programming for different machinery. Industrial computers are a necessity for older machinery, which rely on the industrial computer for programming. The positive aspect with industrial computers is the computers are not manufacturer specific, so if your machinery still requires an industrial computer you are able to replace it with any other industrial computer if necessary.
Industrial computers are not used in newer machinery systems, because new machines’ servo components have programming specific parts built into the equipment, such as drives, which makes the industrial computer obsolete in newer machinery.

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