Beginner's guide to HMI Touch panels for Industrial Automation

HMI means Human Machine Interface. The best definition of HMI is connecting people to processes. HMI is an interactive device. The user is able to interact with a machine through the HMI. He can command a machine and get information, alerts, feedback and analysis of the process in real time mode.

HMI Touch Panel ­ The Popular Hakko Monitouch

This article is written for beginners, who have interests to learn about HMI touch panels for industrial automation. So, let’s begin the journey from the beginning and commence from the word "Automation".

1. What is Automation?

Automation is the technique for controlling industrial process automatically. The control mechanism may be a computer or a programmable logic controller. Industrial processes are born out of a mental map of an engineer or a scientist. The mental map creates the physical tasks that are to be carried out by the machine to make a product or assist other machines on the production line.

The complexity of this mental map will depend on the requirement of the process. When the machine is operated manually, the mental map resides on the operator’s brain. If we want to eliminate the operator, we have to download this mental map to some device which will replace the functions of the manual operator. This device is the HMI, the Human Machine Interface.

2. We’ll design a HMI industrial touch panel for an uncomplicated industrial automation process and try to get an insight of the subject:

Fig-2: HMI touch panel for a simple weigh-fill system.

• An industrial weigh-fill system:

The HMI panel in Fig-2 is for an Industrial Weigh-fill system. This is an industrial process to fill a trolley with pre-set weight of materials.

There are two hoppers, one is a storage hopper and the other one is a weigh hopper. The storage hopper has the material in store. The weigh hopper is fitted with load cells. The weight of materials on weigh hopper is measured continuously. The storage hopper is fitted with two pneumatically controlled electric driven gates.

The gates are designated as full flow and dribble flow. When dribble flow gate is open, materials will dribble out of it at a slow rate. When full flow gate is open, materials will flow out of it at a fast rate. When materials flow out of storage hopper, the blue arrows will scroll down, and in case of weigh hopper, the red arrows will scroll down.

There are three “Gate Open” Green lights and three “Gate Closed” Red lights. These are placed by the side of the TFT resistive touch screen Panel (this is clarified latter). There are no operating buttons on the left hand TFT Panel.

The right hand TFT Panel has Up/Down Touch Button to set the pre-set weight of materials to be filled in the trolley. One green round “Start” touch button and a red round “Stop” button is provided.

The operator will only press the Green “Start” button to initiate the process, and the process will continue in “Auto” mode till the trolley is filled with the pre-set weight.

• HMI TFT resistive touch panel for this weigh-fill system:

HMI panels are TFT resistive touch types. These panels are made of a number of layers. There are two significant layers. One of the layers is electrically conductive, and the other one is a resistive layer. These layers are thin and separated by a thin space. Some points in the layers are designed so that when touched by a finger, the layers get connected. An electrical current is generated by touch, and a voltage is developed in a voltage divider circuit.

This voltage is transmitted to the micro-controller inputs for further processing of the touch signals. The right hand side panel in Fig-2 is TFT resistive touch panel for operator use. The operator can touch the “Start” button to start the operation. The operator has to pre-set the weigh-fill weight by the UP/DN scroll button marked as “Set Weight”. He may touch the “Stop” button to make an end of the operation anytime.

The left hand side blue outlined Screen is a TFT LCD Panel. This is a mimic LCD panel. This will display the operation of the process during actual operation.

To add buttons, elements and to program the HMI it is typically connected to a computer. Then. using a dedicated software the engineer can add graphics, interactive elements and macro commands.

3. Design and applications of HMI Touch Panels:

• Today, HMI Touch Panels, are a most valuable aspect in the world of industrial automation. The design and applications of these panels are quite challenging, and new user-friendly automation systems for industries are born. Let’s find put some of the significant configurations of this HMI Touch Panels. HMI Key Panels are alternative to the conventional keypad operator panels. These are PROFIBUS DP compatible. PROFIBUS DP is used to operate the signals generated by the control keys through a centralized controller in automation production processes.

• Good design is the key factor to get most out of HMI touch panels. The screens are to be created for accurate representation of the automation process. Main screen, Alarm Screens, Key Panels and real time data panels are some of the significant areas to be taken care while designing a particular HMI Touch Panel for a select brand PLC or controller.
• Push buttons are to be grouped to make the panel operation easy for an operator. Color codes are to be selected with reference to the standard industrial codes. Navigation to and from the HMI touch panel should be easy.
• Correct Graphics are to be chosen from the Graphics library. Special applications will require the creation of the appropriate graphics, radio buttons and icons.
• Lastly, HMI Touch Panel design is an artistic job mixed with engineering excellence. It should look excellent with soothing color combinations.

Industry people say that HMI Touch Panels are so easy to operate that even your CEO can learn it in minutes. This is not a tall talk, the usefulness of HMI Touch Panels are beyond any doubt.

See also
HMI Touch Screens Easy to program and versatile touch screens that communicate as standard with a wide range of devices including PLC and inverters.

Hakko Monitouch HMI