HMI - Advantages
The following is a list of some of the most impotant features of having Human Machine interface.
High quality graphics for realistic representations of machinery and processes
This will give the operator and the management a very realistic view of the plant. The operator can control plant without in one central location, this could be very useful when there is a security concerns. The operator does not need to be close to the equipment to control of monitor.
Alarms (Real Time / Historical)
Viewing alarms will help the operator to locate and react faster to any mulfunction of any anomalies. Some of the alarms could be of preventive type, for example to create a warning alarm on a hydraulic tank oil level before the oil level really reaches a critical point.
Historical Alarm logging is very usefull to track problems. It could be used to optimize process. Which in turn would increase productivity and reduce lost time.
Trends (Real Time / Historical)
Trends are very usefull with PID's. You can view the curve used to reach a certain set point. Study of certain values will result in optimizing your process, and it will certainly make if much more efficient.
Simple and complex recipe could be controlled with HMI. This is very usefull and very effective way to execute recipes.
Some of the high quality HMI's will be so flexible that you can simulate a plant in your office. This will help PLC program developers test their program without having a single equipement or devices. This kind of simulation is used more and more to reduce startup time.
This is a very interresting functionality. You can message, page or fax someone when a certain event happens. For example lets say the oil level in the hydraulic tank has reaching a low level. Then low oil level will be triggered and it will page the person in charge to fill up the tank.
Animate equipments and instrument based on operator standards.
They say one picture is better than 100 words. Now this is not only a picture it is an animated one. This will really improve the whole view of the process. Any anomalies will be detected much easier.
Reduce the cost of hardware.
An HMI can replace hundreds of Push buttons, selectors, Lights and so on. As a result less consols and panels and definetly less cables all over the plant.
Today most HMI's can communicate with many different brands of PLC's. Here is a list of most used communications.