With the development of the pharmaceutical industry in the direction of scale and the improvement of the pharmaceutical industry's requirements for output, control performance and equipment stability and reliability, more and more enterprises have owned or began to consider purchasing high-speed tablet presses. As a major manufacturer of high-speed tablet presses, this paper attempts to analyze and compare the electrical control systems of high-speed tablet presses in the current domestic market to help users understand and judge such machines.

According to the information we have, most of the electrical systems of high-speed tablet presses produced in China now use the following three methods: single-chip microcomputer, industrial control computer and programmable logic controller (PLC). The following is a comparison of the performance of these three control systems, from which we can also understand the evolution and development of the electrical control system of the high-speed tablet press.

1. Single Chip Microcomputer

The so-called single-chip microcomputer system is the use of the current market single-chip CPU and other peripheral chips, according to different system design circuit board, the final design into a simple computer system, and on this basis design procedures to achieve the required control functions. This form was very popular in China in the 1980 s, but due to its own reliability and other limitations, in addition to the instrument is still used, the application in the industrial field has been gradually replaced by PLC.

Reliability of single-chip microcomputer: due to the mixed quality of single-chip microcomputer chips in the domestic market at present, a large part of them are inferior products screened out from abroad. in addition, the parameter dispersion of other peripheral components (such as resistors, capacitors, etc.) is also very large. it is impossible for products with small batches to undergo technical processing such as screening and matching, so it is difficult for such products to achieve good consistency and high reliability, because the parameters of any component deviates from the design requirements, the system will be unstable. In addition, all devices are not industrial-grade, anti-interference, especially anti-power interference ability is very weak, and the domestic power supply is generally very poor, coupled with the tablet press frequency control of the power supply interference is very large, therefore, more likely to cause instability of the microcontroller system.

The scalability of the microcontroller: Because the circuit of the microcontroller is specially designed according to certain functional requirements, it is necessary to redesign the circuit to add a function, and the corresponding procedures must be redesigned. This increases the development cost and cycle time for adding functionality.

Maintainability of the single-chip microcomputer: Once the single-chip microcomputer system fails, it is difficult to diagnose the faulty components. The easiest way is to replace the entire system, which increases the maintenance cost.

Operation: At present, the operation of domestic single chip microcomputer system adopts self-designed keyboard, dial switch for setting data and LED for display. The whole panel is complicated and locked. Moreover, in order to reduce the operation keys, one key is often used in design, so it is difficult for operators to operate without instructions. In particular, the fault display can only display the fault code. Once a fault occurs, the operator must read the manual to find the fault, and finally troubleshoot according to the instructions in the manual, so that the troubleshooting time is relatively long. In short, such human-computer dialogue is not friendly enough.

Features: unreliable and cheap.

2. Industrial control computer

The so-called industrial computer system is the use of the current market on the so-called industrial control computer system, on the basis of the design of the program to achieve the design of the function. However, people in the industry know that there is no essential difference between industrial control machines on the market and compatible machines assembled by themselves. First of all, the CPU, which is the heart of the computer, is of non-industrial grade as well as the compatible machine. The rest of the main components such as hard disk, memory, display, etc. are of non-industrial grade. The only difference is that the chassis has been reinforced. Due to its reliability and other limitations, this form is rarely used in industrial fields except for a large number of occasions where it is not directly involved in control as a monitoring machine in factories.

Reliability of industrial control computer: because the main components of industrial control computer are not industrial grade, compared with single chip microcomputer system, anti-interference, especially anti-power interference ability has been improved to a certain extent, but the domestic power supply is very poor, and the frequency conversion speed regulation of tablet press has great interference on the power supply, so it may also cause instability of the system.

Scalability of industrial computer: to add a function, it is necessary to redesign the corresponding program, while the programming of industrial computer is relatively complicated, which will increase the development cycle.

Maintainability of industrial control computer: once the industrial control computer system fails, it is difficult to diagnose the faulty components, so that the maintenance cycle increases, and non-professional personnel can not repair, if the fault is caused by unreasonable program design, due to the lack of appropriate debugging tools, it is also very difficult to find out the cause of the fault.

Operation: There is no difference between the operation of the industrial computer and the general computer, which has high requirements for the quality of the operator. The average worker will have a fear when he sees the computer. Although the operation interface is friendly, it is still not easy to learn for those who are not familiar with the computer system.

Features: price in the middle, reliability improvement is not much.

3. Programmable Logic Controller (PLC):

The so-called PLC system is the use of the current market major industrial control manufacturers of programmable controller, according to the requirements of the selection of different modules, on the basis of the design program to achieve the design function. This form is currently the most widely used in the industrial field. The GZPK100 series high-speed rotary tablet press produced by our company adopts PLC control mode.

Reliability of PLC: The CPU used in imported PLC is an industrial-grade special processor specially designed by the manufacturer. The rest of the components are also purchased directly from the manufacturer. After strict selection of industrial-grade components, in addition, its power supply module is specially designed based on the experience of industrial control of major companies. The anti-interference capability, especially the anti-power interference capability, is greatly improved, even in the interference of poor power supply and variable frequency speed regulation can still work normally.

PLC scalability: to add a function as long as the corresponding increase in the module and modify the corresponding program, and PLC programming is relatively simple, so for the development cycle will be shortened.

PLC maintainability: PLC itself has a strong self-diagnosis function. Once the system fails, it is easy to diagnose the faulty components according to self-diagnosis. Even non-professionals can repair it. If the fault is caused by unreasonable program design, it is relatively simple to find out the fault because it provides perfect debugging tools.

Operation: PLC operation using touch operation terminal, man-machine interface, full-screen display, the above design of a very detailed operation guide, even if the first use, but also according to the prompt smooth operation, which reduces the requirements of the operator, the general workers can quickly grasp. In addition, once the system fails, the screen automatically switches to the failure prompt screen, prompting the cause of the failure and the troubleshooting method. It can even display the location of the fault on the machine, and the maintenance personnel can quickly eliminate the fault according to the prompt.

Features: The price is slightly more expensive than the first two controllers, with good reliability and simple operation.

In addition, the design, manufacture and installation of the electrical system of the GZPK100 high-speed tablet press adopts IEC standard, and the main electrical components are imported from famous foreign manufacturers, thus increasing the reliability of the system. The system chip method adopts the combination of batch chip and single value chip, and the single value chip is one grade higher than the batch chip in terms of effect and technical difficulty.

The operation and display of GZPK100A high-speed tablet press are concentrated on the man-machine interface. Except for the beginning of the main power supply and the emergency stop button, no button operation is required, which greatly reduces the influence of powder on electrical components and indirectly improves the reliability of the electrical system. The protection level of the man-machine interface is IP67, which can resist various harsh environments. The design idea of centralized operation display is more in line with GMP.