Abstract: Position servo systems, with fast and high-precision tracking as their primary objective, are one of the main control methods widely used in high-precision position control. Their drive signals are pulse signals representing position commands. This paper introduces a high-precision position control system applied to a packaging and printing drive system, utilizing the pulse counting and pulse output functions of the high-performance data acquisition card PCL-718 and the pulse position control function of the MSD series fully digital frequency converter. The hardware and software development were also implemented. Keywords: Packaging printing drive industrial computer speed regulating transducer position controlling system. Abstract: Position servo system, which has high accuracy and possesses speed tracing performance, is a type of control system that has been widely applied with high-accuracy position control. Its driving signal is a pulse, which presents the position. In this paper, we propose to combine the pulse counting function and pulse output function of the PCL-718 data sampling card with the pulse position controlling function of the MSD0421A digital variable frequency controller to form a high-accuracy position servo system, which is applied to the driving of binding and printing. In addition, the hardware and software for the control mode are developed. Keywords: driving of binding and printing industrial computer speed regulating transducer position controlling system. 1 Introduction In China, the microcomputer control method is widely used in the drive control system of packaging printing. This control system has the advantages of small size, high reliability, and good economy, but it also has the disadvantages of large interference and difficulty in calibration at start-up. The fully digital AC/DC/AC frequency converter servo drive MSD0421A has a pulse position control function. It uses the number of pulses to represent the position magnitude, thus featuring high control accuracy, fast response speed, and strong anti-interference capabilities. Using it as an actuator in conjunction with the intelligent data acquisition card PCL-718 to form a closed-loop position controller on packaging lines is of great significance. It can solve many problems in packaging printing, such as the difficulty of initial positioning by manual methods, large positioning errors, slow dynamic adjustment, easy misalignment during transmission, and difficulty in color registration. 2. Automatic Color Registration Principle in Packaging Printing There are many reasons for registration errors, such as inflexible parallelism of guide rollers and pressure rollers, poor motion balance, tension fluctuations, uneven ink thickness, ink thermal deformation, and diameter errors of the printing plate roller. This registration deviation is continuously changing in nature, and the difference is not quantitative. Therefore, it is essential to continuously monitor and correct registration errors in a timely manner. Manual color registration typically relies on the printer's visual inspection of registration errors and their experience to manually adjust the movement of the correction roller to compensate for these errors. This significantly limits printing speed and registration accuracy. An automatic color registration system, however, is absolutely necessary to improve both printing speed and registration accuracy. Figure 1 shows a simplified diagram of the gravure printing press production line (only the first four printing units are shown). The printing press is operated by an uncoiler, sequentially passing through each printing unit to print and dry each color, before being rewound by a rewinder. For each color printing, a color mark is printed on the edge of the ink for registration. This color mark line is 10 mm long and 1 mm wide. For accurate registration, the marks of adjacent colors should be parallel to each other and 20 mm apart vertically (longitudinally). The color mark distance in the system is detected by a color mark sensor. In Figure 1, the photoelectric scanning head S detects the color marks printed by units 1 and 2. If the gap between two adjacent color marks is not equal to 20 mm, it indicates a misregistration. The misregistration is calculated by the microprocessor, which outputs a control signal to drive the actuator, causing the corresponding color correction roller ML to move up and down to extend or shorten the travel distance from the previous unit's printing plate roller to the current unit's printing plate roller for dynamic correction. The color registration of each unit's printing is based on the color marks printed in the previous unit. 3 Features and Operation of the MINAS Series Fully Digital AC Servo System 3.1 System Features We use a Japanese Panasonic frequency converter, which is a digital speed control system. It adopts a dedicated digital signal processor (DSP chip), and the hardware is standardized and universal. It is a multi-microprocessor fully digital closed-loop control system. The system software includes an operating system, data transmission, monitoring, diagnosis, and standard function module subroutines. In application, a graphical programming language is used. According to different transmission system structures, the required modules are called up and connected to form a dedicated transmission system. In fact, it is a programmable controller of a real-time control system. Since the microprocessor is the core component of the control system, it can not only perform online rapid calculation and control according to various control ideas and mathematical models, but also has functions such as monitoring, display, protection, fault self-diagnosis, and self-recovery. The MSD all-digital frequency converter is powerful and suitable for high-performance position controllers. It has 38 parameter settings and 6 control modes, among which pulse train position control is the most unique. Because it uses a pulse signal of a certain frequency as the input signal representing the position command, it has higher accuracy and stronger anti-interference ability than analog speed input signals in complex working environments. 3.2 Operation of Pulse Train Position Control Error 1) Before applying the main power supply, apply DC 12-24V voltage. 2) Apply the main power supply to the driver. 3) When SERVO-ON, the motor is in standby mode. 4) In position control mode, release the deviation counter zero signal CL and the pulse command prohibition signal INH, and the motor is in SERVO-LOCK state. 5) Set parameter NO.02 to zero. This mode is the position (pulse train) control mode. 6) Set parameter NO.2 9 to a parameter value. The motor speed is proportional to the input pulse frequency f X P25/P26 X P27 = 2500 X 4Xn/60. The command pulse input mode selection is shown in Table 1. In Table 1, "640" or "2" selects a 90° phase difference input between phases A and B; "1" selects either the CW or CCW direction command pulse; and "3" selects both pulse train command input and symbol input. 4. Data Acquisition Card PCL-718 The PCL-718 multi-functional analog-to-digital interface card is characterized by its wide applicability, comprehensive functions, and high performance-price ratio. It is suitable for original and compatible IBM-PC/XT/386/486/586 series machines conforming to the ISA bus standard. It can be widely used in industrial process control systems and laboratory data acquisition systems. The PCL-718 features easy installation, simple programming, and strong anti-interference capabilities. Users can select different input methods according to their needs. In this system, we use the card's pulse counting and pulse output functions. The PCL-718 has a built-in 16-bit programmable counter 8253. To use it, simply connect the external pulse signal to the channel. Then, call the internal parameters and functions to perform pulse counting and pulse output. 5. Introduction and Design of Automatic Color Coding System This system consists of a PC, a PCL-718 data acquisition card, and an MSD frequency converter servo system as its control core. The MSD uses pulse train position control. Its structure is shown in Figure 2. Control Principle: The entire transmission system starts with a rotary encoder mounted on the shaft. As the transmission system rotates, the encoder emits continuous pulse signals, i.e., n pulses per revolution. Based on the roller circumference, the number of pulses equivalent to 20 mm can be calculated and used as the input signal for the industrial control computer. Each color roller is equipped with a color mark sensor to detect color marks on the printed material. The detected signals are fed back into the calculation, and the software controls the output control quantity to adjust the relative position of the color rollers and eliminate printing misalignment. In multi-color printing, we use the rotation angle of the printing plate cylinder to adjust the printing position. Its closed-loop control is shown in Figure 3. In Figure 3, the electrical pulse signal from the color mark sensor is input to the gating signal of the timer on the data acquisition card. The timer starts counting the pulse signals emitted by the rotary encoder to determine the position. The actuator is an AC servo system driven by a PCL-718 card. The industrial computer compares the detected position signal with a pre-defined standard value in memory to obtain the deviation value. Then, according to the control algorithm, it calculates how many pulses should be generated for compensation based on the pulse deviation. The compensation pulses are obtained from the pulse output terminal of the data acquisition card. The number of compensated pulses is output to the AC driver MSM042A. The driver is in pulse train position control mode, and parameter NO-29 should be selected as "3" in Table 1. This mode is pulse train + sign. The command sign input terminal should be output by the data acquisition card as a high or low level to control the motor's forward and reverse rotation according to the control needs. At this time, the driver can drive the motor to rotate forward or reverse by a certain angle according to the positive or negative value of the deviation to correct the position deviation. 6 System Software Design The system software is developed using VB, allowing direct access to the internal parameters and functions of the PCL-718 during programming, making it easy to use. The system software includes a main program (see Figure 4 for the main program flowchart), a counting subroutine, and an integrated pulse output subroutine. 1) Main Program. 2) Counting Subroutine. ① Set parameters 0, 1, 39; ② Call function 37 to initialize the counter; ③ Call function 43 to start counting; ④ Call function 45 to stop counting and read the count value. 3) Pulse Output Subroutine. ① Set parameters 0, 1, 39, 41, 42, 43, 44; ② Call function 37 to initialize the counter; ③ Call function 46 to start pulse output; ④ When it is necessary to stop pulse output, call function 47 to stop pulse output. The operation interface is shown in Figure 5. As can be seen from Figure 5, the interface displays the total number of pulses, the number of control pulses, and the motor direction. Clicking "Automatic Adjustment" will allow the entire control system to run automatically. In the experiment, we used a pulse signal generator to simulate a rotary encoder and a color mark sensor to randomly detect color mark signals, generating electrical pulse signals to simulate feedback signals, thus forming a control system with good results. 7 Conclusion This paper applies the special function pulse train position control method of a fully digital high-performance frequency converter, which has high accuracy and strong anti-interference capabilities. Using a fully digital high-performance frequency converter AC servo system as the actuator, a PCL-718 acquisition card as the drive device, an industrial control computer as the development tool, and VB to design the interface, a control system was formed and applied to a packaging printing transmission control system to achieve high-precision position control. Because the PCL-718 card's drive module is embedded in the industrial control computer, various control algorithms can be flexibly implemented by changing the module to achieve ideal control accuracy and real-time performance. References: MARLEN VARNOVITSKY A. Development and Comparative Analysis of Pulse-width Modulation Strategy. IEEE.Trans.In dE Letron, 1984. IE -31 (3) Ma Mingjian, Zhou Changcheng. Data Acquisition and Processing Technology. Xi'an Jiaotong University Press, 1998