How can a PLC be controlled without ladder logic?
What Programming Software to Choose?
When considering which programming software to use, there are three main categories to choose from: proprietary, hardware independent and open software. Proprietary software is the software that the manufacturer provides, which is typically easy to use and allows for quick development. The drawback is that proprietary software will only run on that specific hardware platform. Hardware-independent software is third party software developed to program on several different types of HMIs. This type of software gives the developer much more freedom for the HMI selection. The downside to hardware independent software is that it is not as user-friendly as the proprietary. Open Software should only be selected by the advanced programmer. It allows the developer to have complete openness in the design process.
HMI Applications :
The HMI is used throughout various industries including manufacturing plants, vending machines, food and beverage, pharmaceuticals, and utilities, just to name a few. HMIs along with PLCs are typically the backbone of the production line in these industries. The integration of the HMI into manufacturing has vastly improved operations. The HMI allows for supervisory control and data acquisition in the entire system, so parameter changes are feasible as the operator's choosing. For example, in metals manufacturing, an HMI might control how metal is cut and folded, and how fast to do so. An HMI offers improved stock control and replenishment, so the fewer journeys are required out to the vendors. HMIs are used in bottling processes to control all aspects of the manufacturing line, such as speed, efficiency, error detection and error correction. Utility companies may use HMIs to monitor water distribution and waste water treatment.
Advantages of an HMI :
The greatest advantage of an HMI is the user-friendliness of the graphical interface. The graphical interface contains color coding that allows for easy identification (for example: red for trouble). Pictures and icons allow for fast recognition, easing the problems of illiteracy. HMI can reduce the cost of product manufacturing, and potentially increase profit margins and lower production costs. HMI devices are now extremely innovative and capable of higher capacity and more interactive, elaborate functions than ever before. Some technological advantages the HMI offers are: converting hardware to software, eliminating the need for mouse and keyboard, and allowing kinesthetic computer/human interaction.
Advantage of an HMI over a PLC alone :
The advantage to using an HMI over using just a PLC is the fact that there are no disadvantages! Using just a PLC will not provide any real-time feedback, cannot set off alarms nor modify the system without reprogramming the PLC. The key advantage to an HMI is it functionality; an HMI can be used for simple tasks such as a coffee brewing controller, or a sophisticated control unit of a nuclear plant. With new HMI designs emerging every day, we are now seeing HMIs that offer remote access, allowing for access of the terminal while away. Another advantage of an HMI is that the user can personally design the user interface.
HMI/PLC Combination :
How can a PLC be controlled without ladder logic? How does an HMI replace the standard software a PLC comes with? Ladder logic is simply conditional programming. For example, if input 1 is energized, then coil 1 will be powered. A statement has to be true for the output to be executed. The same can be achieved with C programming. However, in order to program an HMI to operate a PLC properly, all the registers of the PLC must be known. A good way to learn how to program a PLC via an HMI is to first start working with the PLC and the software it came with. This helps build an understanding of how to operate the PLC without the HMI. That knowledge will easily transfer over when the user is ready to connect the two units together.
When considering which programming software to use, there are three main categories to choose from: proprietary, hardware independent and open software. Proprietary software is the software that the manufacturer provides, which is typically easy to use and allows for quick development. The drawback is that proprietary software will only run on that specific hardware platform. Hardware-independent software is third party software developed to program on several different types of HMIs. This type of software gives the developer much more freedom for the HMI selection. The downside to hardware independent software is that it is not as user-friendly as the proprietary. Open Software should only be selected by the advanced programmer. It allows the developer to have complete openness in the design process.
HMI Applications :
The HMI is used throughout various industries including manufacturing plants, vending machines, food and beverage, pharmaceuticals, and utilities, just to name a few. HMIs along with PLCs are typically the backbone of the production line in these industries. The integration of the HMI into manufacturing has vastly improved operations. The HMI allows for supervisory control and data acquisition in the entire system, so parameter changes are feasible as the operator's choosing. For example, in metals manufacturing, an HMI might control how metal is cut and folded, and how fast to do so. An HMI offers improved stock control and replenishment, so the fewer journeys are required out to the vendors. HMIs are used in bottling processes to control all aspects of the manufacturing line, such as speed, efficiency, error detection and error correction. Utility companies may use HMIs to monitor water distribution and waste water treatment.
Advantages of an HMI :
The greatest advantage of an HMI is the user-friendliness of the graphical interface. The graphical interface contains color coding that allows for easy identification (for example: red for trouble). Pictures and icons allow for fast recognition, easing the problems of illiteracy. HMI can reduce the cost of product manufacturing, and potentially increase profit margins and lower production costs. HMI devices are now extremely innovative and capable of higher capacity and more interactive, elaborate functions than ever before. Some technological advantages the HMI offers are: converting hardware to software, eliminating the need for mouse and keyboard, and allowing kinesthetic computer/human interaction.
Advantage of an HMI over a PLC alone :
The advantage to using an HMI over using just a PLC is the fact that there are no disadvantages! Using just a PLC will not provide any real-time feedback, cannot set off alarms nor modify the system without reprogramming the PLC. The key advantage to an HMI is it functionality; an HMI can be used for simple tasks such as a coffee brewing controller, or a sophisticated control unit of a nuclear plant. With new HMI designs emerging every day, we are now seeing HMIs that offer remote access, allowing for access of the terminal while away. Another advantage of an HMI is that the user can personally design the user interface.
HMI/PLC Combination :
How can a PLC be controlled without ladder logic? How does an HMI replace the standard software a PLC comes with? Ladder logic is simply conditional programming. For example, if input 1 is energized, then coil 1 will be powered. A statement has to be true for the output to be executed. The same can be achieved with C programming. However, in order to program an HMI to operate a PLC properly, all the registers of the PLC must be known. A good way to learn how to program a PLC via an HMI is to first start working with the PLC and the software it came with. This helps build an understanding of how to operate the PLC without the HMI. That knowledge will easily transfer over when the user is ready to connect the two units together.
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