The concept of managing a control system involves a systematic approach, and the operating procedure includes determining the machine order, input and output addressing, and PLC programming. Troubleshooting is performed to ensure that the program runs according to the intended process sequences and provides the desired response from the control valves, the final control elements connected to the PLC. The design of the control system is done using programmable logic controller (PLC).
The CX-Programmer is the programming software that was used to design the operating system in which the programming language of the software resides. In addition, the design of the process flow chart and timing diagram are also important for a successful outcome of the project. The configuration of both modules was carried out to obtain the desired result of the project.
It is also important to implement the control valve as the output of the analog controller in the control system.
Definition ofBatch Process
Its complexity is why batch control automation has lagged behind continuous control or even sequential discrete parts manufacturing. Batch control refers to the type of control typically used with a batch process. A batch process control in which the functions of material transfer and/or material processing are cyclical with repeatable results.
A process is a process in which the measured and controlled variables are manipulated to deliver a product at a specified continuous rate. A batch process is a process that yields a homogeneous, discrete amount of product at the end of a specified time.
Batch Cycle Time
Application ofBatch Process in Industry
Despite the specific and almost stubborn characteristics of batch control, using batch-driven facilities is very challenging. Industrial batch processes are similar to the process of baking a cake, but are scaled up to produce a larger amount of material. Food, beverages, pharmaceuticals, paints, fertilizers and cement are a few of the categories of products produced using batch processes.
Some products such as food, beverages and pharmaceuticals require accurate tracking of batch information for safety and regulatory purposes [6].
PLCHistory
PLC Components
Memory in a PLC system is divided into program memory which is usually stored in EPROM/ROM and operating memory. RAM memory is necessary for program operation and temporary storage of input and output data. Input/output units are the interfaces between internal PLC systems and external processes to be monitored and controlled.
Since the PLC is a logic-based device with a typical operating voltage of 5 volts, and external processes usually require higher power and currents, the I/O modules are optically or otherwise isolated. The I/O modules are designed in this way to minimize or eliminate the need for any intermediate circuitry between the PLC and the process to be controlled.
PLC Operation
Typical memory sizes of PLC systems are around lkb for small PLCs, several kb for medium-sized PLCs, and greater than 10-20 kb for larger PLCs depending on requirements. Since they are only used in the development/testing phase of a PLC program, they are not permanently attached to the PLC. The program in a ladder diagram or other form can be designed and usually tested before being downloaded to the PLC.
The unit, once connected to the PLC, can download the program and allows for real-time monitoring of its operation to aid debugging. Once the program is found to be working as required, the programming unit is disconnected from the PLC continuing the operation [8]. Ladder diagrams, function blocks, and the sequential function map are the most common types of languages found in programmable control system design.
Ladder diagrams form the basic languages of PLCs, while function blocks and sequential function diagrams are categorized as high-level languages. Basic programmable control languages consist of a set of instructions that will perform the most common type of control functions such as relay switching, timing, counting, sequencing, and logic. However, the instruction set may vary from one controller to another because it depends on the controller model, specifications and requirements.
The high-level languages arose from the need to execute more powerful instructions beyond simple timing, counting, and ON/OFF control. Level languages are used for analog control, data manipulation, reporting, and other functions that are not. possible with the basic instruction sets. The . The language used on a PC determines the range of applications in which the controller can be applied. Depending on the size and capabilities of the controller, one or more languages can be used.
Ladder Languages
Control sports generally consist of a set of input conditions represented by relay contact type instructions and an output instruction at the end of the sport represented by the coil symbol. The coil symbols represent all the outputs, where contacts represent conditions that must be evaluated to determine the control of the output. Each coil and contact is referenced with an address number that is used to identify the operating conditions.
Contacts can be placed in any configuration, such as series, parallel, or series/parallel, required to control a particular output. In order for an output to activate or energize, at least one contact path must be closed from left to right. When logical continuity exists in at least one path, the run condition is said to be TRUE.
PLCAdvantages
Timing Diagram
The analog data can be representative of temperature, pressure, flow rate, weight, thickness, viscosity, humidity or any other property of interest to the process. In addition, a corrective action is often required to ensure that the process remains within specifications. A variety of approaches can be used for process control, depending on the complexity of the process being controlled.
A representation of the process showing its current status and a history of data recorded at various points in the process is often provided to the PLSs. In PLC programming, developing the flowcharts and timing diagrams is the first step to do before writing the ladder program. The manufacturing process involves a sequential processing that leads to the production of finite quantities of liquid soap by subjecting quantities of the raw materials to an ordered set of processing activities such as weighing, heating and mixing over a limited period of time set using the timer with one or more pieces of equipment.
Low level sensor 1 (LS001) detects the low level of the. and LC003) until the set point is reached. This project focused on an approach to implement an analog module of PLC for a batch process. First, the input and output ranges and the number of inputs and outputs required for the process were determined.
After the wiring process was completed, the process flow was programmed into the ladder diagram. Led analog inputs and outputs (0 to 5 V and 0 to 20 mA analog inputs are selected by the connected terminals. O to 5 V and 0 to 20 mA analog outputs are selected by the connected terminals.). The analog I/O card is an internal card with four analog inputs and two analog outputs as shown in Figure 3-4.
The machine sequence ofoperation
The configuration in the wiring between the PLC and the devices was done before the development of the ladder diagram, since the address dictates the exact meaning of the contacts in the ladder diagram and must be specified. The completed program was transferred to the memory of the programmable controller and simulations were done in programming to ensure that the designed process works properly and to validate the behavior of the system. Troubleshooting is required to ensure that the program can operate in accordance with the intended process sequences and provide the desired response of the control valves that were connected to the PLC.
The process is also to correct any errors encountered during the implementation of the program. Once the program is developed and tested, the implementation of the system can be realized. The program was then run to observe the response of the control valve to the designed control system.
Material borax is used to change the pH of the mixture (liquid soap) while a small amount of fragrance is enough to bring out the fragrance. Therefore, dosing pumps are used in the process to control the amount of borax and fragrance (kasturi oil) by flushing out the materials in a small amount. The process sequences of liquid soap making are simplified to a flowchart for easy understanding as shown in the figure.
There are 4 digital inputs, 12 digital outputs, 2 analog inputs and 2 analog outputs that were used in the programming design based on the process sequences. For the analog controller, the Move instruction was used to control the opening of the control valve. The opening of the valve was determined via the input value set in the DM memory of the PLC, namely DM 400 and DM 401 for control valve 1 and 2 respectively.
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Literature reviews and studies were conducted to increase the understanding of batch process control and programmable logic controller (PLC). A batch process involves sequential processes leading to the production of finite quantities of material by subjecting quantities of input materials to an ordered set of process activities over a finite period of time using one or more pieces of equipment. A PLC consists of a central processing unit (CPU) that contains the application program and input and output interface modules that are directly connected to field I/O devices.
The software used was CX-Programmer, which is installed in the computer and connected to the PLC. The developed program was transferred to PLC and tested to observe that the outputs obtained are as desired. The CX-Programmer programming software was used to develop the ladder diagram for the PLC implementing the batch control.
This approach proves to be effective in designing a logic ladder diagram for a PLC to control a batch process, in this case a liquid soap making process. It is recommended to implement the project using a different PLC family, such as Allen-Bradley and Siemens, to get acquainted with a different tool and skills in ladder diagram programming.
APPENDICES
APPENDIX A
APPENDIX B
