Abstract: This paper introduces the application of Yonghong FBS series PLC in an automatic spray painting line control system. From the perspectives of hardware and software design, it describes the superior and efficient PID temperature control and high-precision analog signal processing capabilities of the Yonghong FBS series PLC.
Keywords: Yonghong PLC, PID control, analog output, linear conversion
Foreword
With increasing market demand, environmental protection requirements, and growing emphasis on worker safety, automating the spray painting production line is undoubtedly the wisest choice. Automation significantly improves production efficiency, reduces environmental pollution levels, and eliminates the occupational disease risks associated with manual spray painting.
Introduction to the coating line process
The automatic spraying line mainly consists of loading and unloading conveyor belts, a main conveyor belt, a heating section, a spray gun system, a product rotation system, a dust removal system, and a UV curing system. Products are conveyed from the loading conveyor belt to the main conveyor belt, pass through the preheating zone to the dust removal system, then enter the automatic spraying booth. After undergoing 360° rotation spraying, the products flow into the heating zone, are cured by the UV curing system, and finally exit from the unloading conveyor belt.
II. Control System Composition and Product Application Characteristics
Because this control system requires centralized control of multiple frequency converters and multiple temperature channels, a control mode combining a touch screen, PLC, analog output module, and temperature control module is adopted. This project utilizes Yung-Hong touch screen, Yung-Hong FBS series PLC, Yung-Hong FBS-4DA analog output module, and Yung-Hong FBS-TC6 temperature control module to complete this project.
Features and brief introduction of Yonghong FBS series PLC:
The FBs series PLC was launched by Yung-Hong Company in 2004. Compared with PLCs of the same level from other major manufacturers, the FBS-PLC has many features and advantages:
It features 8 high-speed counters with a maximum counting frequency of 920kHz and supports 8 counting modes: A/B×4, A/B×3, A/B×2, A/B, CLK/DIR×2, CLK/DIR, U/D×2, and U/D.
High-speed timer with 5 groups of 16-bit or 32-bit 0.1ms time bases
It features high-speed NC positioning control output with 4 axes capable of linear interpolation, and a frequency up to 920KHz.
Features 16 positive and negative edge interrupt inputs
Features 36-point capture input
It features 4 sets of high-speed PWM outputs, with a maximum frequency of 18.4KHz/184KHz and a resolution of (1000/100). It has an extremely fast response speed, high accuracy, and the functional features of a medium-to-large-sized PLC.
Introduction to Yung-Hong FBS-4DA Analog Output Module:
The FBs-4DA is an analog output expansion module for the FATEK-FBs series PLC, providing 4 channels of 14-bit analog output signals. During application, the type and amplitude of the analog output signal can be configured using the jumpers within the module. Furthermore, the output code format can be set to unipolar or bipolar, allowing for a more intuitive relationship between the output signal and the output code. For safety, if the CPU does not access the module for more than 0.5 seconds, the output will automatically switch to zero, i.e., 0V (when the output is set to a voltage signal) or 0mA (when the output is set to a current signal).
Introduction to Yung-Hong FBS-TC6 Temperature Module:
To meet the needs of the broad temperature control application market, the FBs-PLC offers five temperature measurement modules in two main categories: thermocouples and platinum resistors. The FBs-TC6 temperature module can be used for temperature measurement with 6 thermocouple inputs, and there are 8 thermocouple types to choose from: J, K, T, E, N, B, R, and S. The temperature measurement module adopts a time-sharing multi-tasking design, with each temperature module occupying only 1 numerical input (Input Register) and 8 digital outputs in actual I/O addressing. A single PLC host can perform up to 32 temperature measurements, and the temperature measurement update rate can be selected in two modes: normal (update time of 4 seconds, resolution of 0.1°) or fast (update time of 2 seconds, resolution of 1°).
Implementation of three important functions
PID control of temperature
Figure 1. Wiring diagram of FBS-6TC
Using PID control to control temperature is currently a relatively efficient and accurate control method. Yonghong PLC provides very convenient PID temperature control instructions. The following figure shows the temperature control program for this project.
Figure 2. Yonghong temperature control PID program
Analog output control frequency converter
Yung-Hong's analog output control is also very convenient; simply input the required value into the corresponding output buffer. The following is the wiring diagram of the FBS-4DA:
Figure 3 Wiring diagram of FBS-4DA analog output module
In this project, we need to input the inverter's control frequency on the touchscreen to control the motor's speed. We need it to be adjustable from 0-50Hz. However, the 14-bit resolution of the FBS-4DA only has a numerical range of 0-16383. Usually, we need to perform complex calculations to make the touchscreen input match the inverter output. Here, we can easily accomplish these functions using the linear conversion instructions of the Yonghong PLC. Below is the FBS-PLC analog linear conversion output program and the touchscreen display.
Figure 4. FBS-4DA Analog Linear Conversion and Output Program
Figure 5. Touchscreen temperature and frequency setting screen
Summarize
Automated spray painting production lines significantly improve production efficiency, reduce environmental pollution, and eliminate the occupational disease risks associated with manual spraying. Based on the powerful functional instructions and excellent peripheral modules of Yonghong PLCs, a cost-effective and efficient upgrade solution for implementing automated spray painting line transformation is provided, making it highly valuable for promotion and application.
References
1. Yung-Hong FBS Series PLC User Manual - 1
2. Yung-Hong FBS Series PLC User Manual - 2
