Current control systems employ a PLC or Programmable Logic Controller as a way to control motors, valves and many other gears used in a procedure. Computer based Human Machine Interface(HMI) products offer the measures by which process personnel interact with the PLC control system. A well-designed combination of PLC’s and HMI’s can be a solid foundation for your process automation needs.
A basic PLC system consists of the following sections:
- Input/ Output Section: The input section or input module consists of devices like sensors, switches and many other real-worldinput sources. The input from the sources is linked to the PLC via the input connector rails. The output section or output module can be a motor or a solenoid or a lamp or a heater, whose functioning is controlled by varying the input signals.
- CPU or Central Processing Unit: It can be a hexagonal or an octal microprocessorand is said to be the brain of the PLC. It carries out all the processing related to the input signals in order to control the output signals based on the control program.
- Programming Device: The program of control logic is written in this platform.It can be a handheld device or a laptop or a computer itself.
- Power Supply: It generally works on a power supply of about 24 V, used to power input and output devices.
- Memory: The memory is divided into two parts- The data memory and the program memory. The program information or the control logic is stored in the user memory or the program memory from where the CPU fetches the program instructions. The output and input signals and the counter signals and timer are saved in the input and output external image memory respectively.
Why Chose PLC and HMI Programming?
Programmable Logic Controllers propose businesses the chance to really modify their mechanical processes. PLC delivers automated solutions by initiating operation based on a system of inputs and outputs, and thus performing as the “brain” of the control system. Other common programming languages used include:
- Structured Text
- Sequential Flow Chartor SFC, very similar to a traditional flowchart
- Instruction List
- Function Block Diagram
PLC programming is extremely valuable. Advantages or benefits of PLC are:
- Minimize the monotony of simplistic work tasks
- Simplify wiring and reduce material costs
- Generatedynamic and complex procedures that out-of-date techniques like mechanical relay-based control just cannot control
- Offercost effective solutions to even the minor and major manufacturers looking for solutions to process control, complex assembly, manufacturing and testing
HMI is the best choice because of its user-friendliness of the graphical interface. The graphical interface contains color coding that allows for easy identification. Advantage or benefits of HMI are:
- Reliable Messaging
- Easier Overall Management of Plant
- Accurate Testing with Simulation
- Cost Reduction
- Improved Communications
CoreSystems blends the right components with customized design to build quality automation solutions. Our aim is to generate successful and well documented programs that merge well with present system logic. Our widespread system control knowledge of current development platforms and our history permits us to offer proven technologies that can progress your process efficiencies.
What is Done During PLC and HMI Programming?
PLC or Programmable Logic Controller from the I / O signals is responsible for the control of the entire machine or equipment. Its programming, in addition to meeting production requirements, must also be structured and accessible to provide fault diagnostics quickly and accurately.
A Programmable Logic Controller program is generally written on a computer and then downloaded to the controller Most PLC programming software offers programming in Ladder Logic. Ladder Logic is the traditional programming language. Due to its visual nature Ladder Logic is simpler to employ than many other programming languages. Some PLC manufacturers supply control programming software.
When operators don’t have easy access to a PC nor laptop close to the installation or the machine, is hard to face the task of creating some backups by downloading or uploading the PLC program or modification. For this reason, there’s a method to upload/download the PLC program directly from or to a USB through the Human Machine Interface.
There are a few key features that set PLCs apart from industrial PCs, microcontrollers, and other industrial control solutions:
- Input and Output– The PLC’s CPU stores and processes program data, but input and output modules connect the PLC to the rest of the machine; these I/O modules are what provide information to the CPU and trigger specific results. Input output can be digital or analog. Users can match and mix a PLC’s Input output in order to obtain the correct configuration for their application.
- Communications – APLC is also connected with other types of systems. Users might want to export application data recorded by the PLC to a supervisory control and data acquisition (SCADA) system, which monitors multiple connected devices. PLCs propose a range of communication protocols and ports to make sure that the PLC can communicate with these other systems.
- HMI – In order to intermingle with PLC in real time, users need a Human Machine These operator interfaces enable users to review and input information to the PLC in real time, by providing interfaces with simple displays, with a text-readout and keypad, or large touchscreen panels.
A manufacturing line must first be working with a Programmable Logic Controller (PLC) so as to be integrated with an HMI. It is the PLC that takes the information from the sensors, and transforms it to Boolean algebra, so the HMI can decipher and make decisions. This is where PLC and HMI interface.
The programming of HMI as its name says, is responsible for the provision of interface with the machine. Thus, from network communication with the CLP, Programming of HMI provides a series of information to operators and other users of the system, such as: fault diagnosis; Production reports; Status of equipment; Manual controls etc. An HMI Programming application need an intuitive and friendly function and its resources must be rightly employed according to the customer needs.
Choosing an HMI:
An HMI is a considerable purchase thus it is vital to know correctly what is needed of it. An HMI is used for three primary roles:
- The place of LEDs, On/ Off buttons, is replaced by the pushbutton replacer. The elimination of these mechanical devices is possible because the HMI can provide a visual representation of all these devices on its LCD screen, while performing all the same functions.
- The Data Handler is utilized for applications thatneed monitoring and stable feedback. Most of the times these Data Handlers come arranged with large capacity memories.
- The overseeris the last of the HMI three types. These are centralized systems that watch and regulate whole sites or complexes of large systems expanded over vast areas
At CoreSystems we create programming solutions for HMI and PLC devices separately designed for every customer. CoreSystem team with numerous years of experience in creating solutions in cutting-edge sectors such as the cooling, chemical and machinery industries, offers each project with fresh characteristics to make sure a straightforward and visual user communication with the process.
Features like remote connectivity that is through mobile, tablet or PC or the sending of alarms makes it simple to obtain the control and analyze various processes anyplace and at any time. Technical support services are also provided. This support, along with our connectivity solutions, ensures assistance is provided instantly and remotely in the event of any incident. We work with PLC brands which offer a guarantee of reliability and robustness over a long period of time.
How is HMI PLC Programming Done?
PLC programming is done mostly with the help of ladder language. Procedure for PLC programming using ladder language is given below:
- Analyze and Get the Idea of Control Application: The primary step to program the PLC is to get the idea for which you are going to develop an application-based program.
- List All the Conditions and Get the Design using Flowchart
- Open and Configure the PLC Programming Software: Open the programming software installed in the PC that comes with PLC hardware.After selecting the hardware model of the PLC, configure it with proper output and input From the listing of the programming languages, chose ladder language and provide a name for the program after selecting the hardware processor.
- Add the Required Rungs and Address Them: Add the required rungs based on the control application logic and give the address to the each and every input and outputs.
- Verify if there are anyErrors and Simulate It: Locate the Online section in the menu bar and select Online. Check for the errors and make necessary changes after selecting Offline.
- Download the Program to PLC CPU Memory: After the successful simulation of the program, download the program to CPU by selecting the Download option through a network or communication cable.
Given here are the steps through which a PLC and HMI interface or communicate:
- Copy the PLC program into an USB memory stick
- Insert the memory stick into the USB port of the HMI
- Enter the system menu of the HMI
- Enter the “Up/Download” sub menu
- Select “HMI <->PLC” transfer mode by navigating through the “LEFT” and “RIGHT” buttons at the bottom
- PressUSB on left side of the screen and chose the PLC program file you need to download
- On the right part of the screen, select the port that is connected to the PLC
- After selecting the port, HMI will search PLC automatically
- After the PLC is detected by the HMI user can now download the program by clicking Download button
An example of HMI-PLC interface
The requirements for data exchanges between a PLC and an HMI station are basically:
- This first part of basic requirements is the components for data exchange.
- A physical link that is obtainableto PLC as well as HMI like an Ethernet cable or a RS-485 connection with the adequate ports on both.
- A common protocol that can exist on the selected physical connection.
- Protocol drivers that will bind the communication interface to the protocol.
- The parttwo is what is switched between the HMI and the PLC.