PLC & HMI Programming

  • Does HMI Require PLC hmi programming?

Two tools often utilized in industrial work environments are HMIs and PLCs. While Human Machine Interfaces are necessary for digital visualization and controls, Programmable Logic Controls are employed to control electronics, control mechanisms, and more. As such, a common question here at Keltour is whether HMI requires PLC to function. Therefore, to better understand these two applications, we will answer the question “does an HMI require PLC” and more below.




What is PLC and HMI programming?


PLC programming uses a specialized language, such as ladder logic, to create programmable logic controllers that run on a PLC device. The PLC acts as the “brain” of an automation system, receiving input from sensors and other devices, processing that information, and then issuing commands to control other devices, such as actuators, motors, and pumps. PLC programming enables the creation of complex control systems that can respond to changes in the process and make decisions based on that information.

HMI programming entails developing visual interfaces, such as screens and graphics. This enables operators to monitor and regulate a procedure. An HMI interface can display data such as process status, system alarm systems, and current operation variable values. HMI programming enables technicians to communicate with the process control system, such as adjusting setpoints, acknowledging alarms, or viewing historical data. HMI programming is frequently done with commercial software packages and can be combined with PLC programming.

PLC and HMI programming, when combined, form the foundation of production process management systems, enabling sophisticated automation and management of complex processes.

What are HMI requirements?


The following are the prerequisites for an HMI systems(Human-Machine Interface) in an automated production configuration:

·  User-friendly interface: The interface should be easy to navigate and understand, allowing operators to quickly access the information they need.

·  Real-time information: The HMI should display real-time information about the process, such as current values of process variables, system alarms, and process status.

·  Scalability: The HMI system should be scalable, allowing for the addition of new information and functionality as the process evolves.

·  Customizability: The HMI development system should be customizable, allowing operators to configure the interface basic functions to meet their specific needs and requirements.

·  Data logging and trending: The HMI system should be capable of logging and trending process data, providing a historical record of process behavior.

·  Remote access: The HMI system should allow for remote access, allowing operators to monitor and control the process from remote locations.

·  Security: The HMI system should have adequate security measures set up to avoid unauthorized access to the process control system.

·  Reliability: The HMI system should be reliable, ensuring that operators can access the information they need when they need it.

These requirements ensure that an HMI system provides the necessary information and functionality to effectively monitor and control an industrial process while also being user-friendly, scalable, secure, and reliable.

What is the advantage of an HMI over a PLC alone?


Furthermore, in industrial automation, an HMI (Human-Machine Interface) has several benefits over a PLC (Programmable Logic Controller) on its own. Here is a more detailed explanation of some of these advantages in more detail below:

·  Improved visibility: An HMI provides a graphical interface that displays real-time information about the process, allowing operators to quickly understand the status of the system and make informed decisions.

·  Enhanced user interaction: An HMI allows operators to interact with the process control system, for example, to adjust setpoints, acknowledge alarms, or view historical data, whereas a PLC alone does not provide a direct interface for user interaction.

·  Improved situational awareness: An HMI can display information such as process status, system alarms, and current values of process variables, providing a complete picture of the process and improving situational awareness.

·  Increased efficiency: An HMI can automate repetitive tasks and reduce the time needed to perform manual processes, increasing efficiency and reducing the potential for operator error.

·  Data logging and trending: An HMI system can log and trend process data, providing a historical record of process behavior and allowing for improved analysis and decision-making.

Why is HMI not communicating with PLC?


Moreover, there could be numerous explanations for why an HMI (Human-Machine Interface) in an automated production line configuration is not interacting with a PLC (Programmable Logic Controller):

·  Network connectivity: The HMI and PLC may be connected to different networks, or there may be an issue with the network connectivity, such as a broken cable or a network configuration error.

·  Incorrect IP addresses: If the HMI and PLC have incorrect IP addresses, they will not be able to communicate with each other.

·  Communication protocol mismatch: The HMI and PLC must use the same communication protocol in order to communicate. If the protocols are different, the two devices will not be able to communicate.

·  Driver compatibility: The HMI software may require a specific driver to communicate with the PLC. If the driver is not installed or is not compatible with the PLC, communication will not be possible.

·  Firewall settings: A firewall may block the communication between the HMI and PLC. If this is the case, the firewall settings must be adjusted to allow communication between the two devices.

·  Hardware failure: The HMI or PLC may have failed, causing communication to be lost.

How is HMI connected to PLC? 


If you’ve decided to connect an HMI and PLC, here is how you would go about doing so to ensure a modern industrial automation solution in your work environment:

·  Choose a communication protocol: There are several communication protocols that can be used to connect an HMI and a PLC, such as Modbus, Profinet, or EtherNet/IP. Choose the protocol that is supported by both your HMI and PLC and that meets the requirements of your application.

·  Connect the HMI to the network: Connect the HMI to the network using a communication cable, such as Ethernet or serial. Make sure the HMI is configured with the correct IP address, subnet mask, and other network settings.

·  Connect the PLC to the network: Connect the PLC to the same network as the HMI using the same communication cable. Make sure the PLC is configured with the correct IP address, subnet mask, and other network settings.

·  Configure the HMI: Use the configuration software that comes with your HMI to set up the communication parameters, such as the IP address, port number, and communication protocol.

·  Configure the PLC: Use the programming software that comes with your PLC to set up the communication parameters, such as the IP address, port number, and communication protocol.

·  Test the connection: Use the software tools provided by your HMI and PLC to verify that the two devices can communicate with each other. Ensure that you can send and receive data between the two devices.

·  Develop the HMI screens: Use the HMI software to create the screens that will be displayed on the HMI. These screens should display the information and controls that are needed to operate the machine.

·  Configure the PLC program: Use the programming software to create the PLC program that will control the machine. The program should receive the commands from the HMI and control the machine’s actuators and other components.

Does HMI need PLC?


So, does HMI need PLC? Well, an HMI (Human-Machine Interface) does not strictly require a PLC (Programmable Logic Controller) in an industrial automation setting, but a PLC is commonly used to control industrial processes and provide real-time data to the HMI for display. An HMI can be connected to other types of controllers or devices that provide the necessary process control and data for display, such as a DCS (Distributed Control System), a PAC (Programmable Automation Controller), or a standalone data acquisition system.

The use of a PLC in conjunction with an HMI provides several benefits, such as increased efficiency, improved visibility, user interaction, and enhanced situational awareness. By providing a graphical interface and allowing the operator to interact with the process control system, an HMI enhances the capabilities of a PLC and improves the overall performance of an industrial automation system.

Is it HMI software or hardware?


An HMI system is a combination of hardware and software that allows operators to interact with industrial machinery and control systems. The software component of an HMI system provides a visual interface that displays relevant information about the machine’s status, such as its current operation, performance, and alarms. This information is typically displayed on a monitor, which can be a dedicated touchscreen device or a computer screen.

On the other hand, the hardware component of an HMI system includes the physical buttons, switches, and other input devices that allow the operator to control the machine. For example, the hardware might consist of buttons to start and stop the machine or touch screens that would enable the operator to enter data or make selections. Both the software and hardware components of an HMI system are designed to be user-friendly, intuitive, and easy to understand so that operators can quickly and easily access the details they require to control the machine.