HMIs can be classified based on various criteria such as their physical form, functionality, and application. Here are some common classifications of HMIs:

1. Physical Form:

   • Panel-mounted HMIs: These are standalone devices installed directly on machinery or equipment panels. They typically feature a touchscreen or a combination of buttons and a display.
   • Rack-mounted HMIs: These HMIs are mounted in standard equipment racks or cabinets alongside other control components.
   • Portable HMIs: These HMIs are handheld devices or tablets that provide mobility for operators to monitor and control processes from different locations within a facility.
   • Embedded HMIs: These are integrated directly into machinery or equipment and may not have a standalone physical interface. Instead, they may utilize embedded displays or interfaces for interaction.

2. Functionality:

   • Basic HMIs: These HMIs provide essential functions such as monitoring system status, displaying alarms, and basic control operations.
   • Advanced HMIs: Advanced HMIs offer additional features such as data logging, trending, recipe management, remote access, and integration with higher-level systems like SCADA or MES.
   • Safety HMIs: These HMIs are designed specifically for safety-critical applications and may include features such as SIL (Safety Integrity Level) certification, safety interlocking, and emergency stop functions.

3. Application:

   • Process HMIs: These HMIs are used in continuous process industries such as oil and gas, chemical, pharmaceutical, and food and beverage production.
   • Discrete HMIs: Discrete HMIs are utilized in discrete manufacturing industries such as automotive, electronics, and consumer goods, where products are produced in distinct units or batches.
   • Building Automation HMIs: These HMIs are used in building management systems to control HVAC, lighting, security, and other building systems.
   • Machine HMIs: Machine HMIs are designed for controlling individual machines or equipment, such as CNC machines, robots, packaging machines, and industrial presses.

4. User Interface Type:

   • Touchscreen HMIs: These HMIs feature touch-sensitive displays for intuitive interaction with graphical elements and controls.
   • Keypad/Button HMIs: HMIs with physical buttons or keypads for manual input and control.
   • Hybrid HMIs: These HMIs combine touchscreen functionality with physical buttons or knobs for enhanced versatility.

5. Communication Protocol:

   • Ethernet/IP HMIs: HMIs that communicate over Ethernet/IP networks, commonly used in industrial automation applications.
   • Modbus HMIs: HMIs that support the Modbus communication protocol, widely used in industrial control systems for data exchange between devices.
   • Profibus/Profinet HMIs: HMIs compatible with Profibus or Profinet industrial communication standards commonly used in manufacturing and process automation.

These classifications help in selecting the appropriate HMI solution based on the specific requirements of the application, the environment, and the level of functionality needed for effective control and monitoring.