Operator control computers run a program with graphic screens and popup windows which allow the operator to control the process systems. These operators of programs interface are referred to as Man Machine Interfaces (MMI) or Human Machine Interfaces (HMI). Then next we will call it as HMIs.
There are four major components in HMIs. They are:
1. Communication Drivers
PCs have different language with PLCs. In order to make them communicate with each other a translator is needed. The translator is communication driver. Each different type of communication network and each different type of PLC requires a specific communication driver.
2. The data collector
The data collector gathers data from and sends data to determine that data needs to be updated and then initiates the data transfer by using the device drivers to perform actual communication.
3. The database
The database is a reference for the data collector and data display windows. Both data configuration and real time data is stored in database. The real time data is the process data from the production line, via the PLC, and the data configuration consists of data devices by the programmer when the application was designed.
4. The data display
The data display consists of popup windows and Windows. The operator interacts with the graphic on the popup windows to control and monitor the process system.