Weighing and filling machine design using electronic scales to display the cumulative filling weight, through the computer to achieve human-computer interaction to control the size of the filling weight. The size of each filling and weighing and the final number of filling can be set through the computer interface. Signal interaction between the computer and the filling machine through the microcontroller and its interface to achieve.

Liquid filling machine principle

Automatic filling machine has now been widely used in industrial processes in a variety of liquid weighing measurement, such as a variety of acids, alkalis, salt and other corrosive media; a variety of slurry weighing measurement, forming a unique field of application. The weighing and filling machine will amplify the weight signal sent by the weighing module and convert it into the standard electrical signal output which is proportional to the weighing signal, in order to display, accumulate and adjust the control.

Weighing and filling machine can realize quantitative volume filling, used to meet the need to correct the filling of some weighing errors, through mechanical or electronic methods to carry out the control of high and low liquid level, can control solenoid valves, pumps, etc., so as to realize semi-automation or full automation, according to the selection of different products and different. The opening and closing of the valve in the automatic filling machine is controlled by the solenoid valve coil, the solenoid valve is an actuator that uses electromagnet to control the fluid, which is widely used in the switching control of the fluid.

Filling control process

Filling system filling action is completed through the control of filling machine software and hardware with Lotus, in the filling system design hardware basis, weighing instrumentation signals through the weighing filling machine control interface box control, processing, and then passed to the calculation, so that the operator through the interface prompts the upper computer, issued a variety of filling device filling command, and then through the weighing of the filling machine control interface box to control a variety of filling actions The operator will then control the various actions of filling through the control interface box of the weighing and filling machine to achieve the expected filling requirements of the people. The filling process is controlled through the computer interface. The computer interface provides the control volume including: each filling volume; filling times; the frequency of the filled fluid; filling start; filling end.

Specific filling process is as follows: when the operator presses the F3 key on the computer keyboard, the cursor comes to the "number of filling pulses", enter the filling volume of each filling (in the form of the number of pulses entered in the form of pulse equivalent calculation can be obtained by filling the volume), type "ENTER After keying "ENTER", the cursor automatically jumps to the input position of filling times, waiting for the input of the number of times to be filled, to be filled the number of times input is complete, at this time, the parameter of the filling has been set up. Press the "start filling" key, the filling stop valve opens, the filling work really begins, when the number of filling times, automatically stop working, filling stop valve closed. When the filling times are reached, the work will stop automatically and the filling stop valve will be closed. Or when the filling times are not reached, if you don't want to continue to fill, you can press the end filling key to force it to quit and stop filling. In addition, in order to facilitate the need for error correction, you can also realize the quantitative filling, that is, when the set filling volume is reached, the filling valve automatically closes, stop filling. Completion of this process requires the control of hardware and software together with the realization of the filling start and stop valve opening and closing, the counter of the pulse accumulation counting and frequency counter in the frequency reading.

Logic control function design

In the filling control, filling equipment are inseparable from the software and hardware to cooperate with each other to realize the weighing and filling machine signal transmission and logic control, in this liquid filling machine is the same.

This liquid filling machine, the completion of the work needs to be filled between the upper computer and the lower computer to achieve the weighing and filling machine signal interaction between the various parts of the transfer. Computer CPU and peripheral equipment (electronic weighbridge) between the pulse accumulation data transmission, and filling start-stop valve between the control signal and status signal transmission, so the use of the computer's EISA interface, the design of a computer and liquid filling machine signals and data transfer between the ESIA bus PC card, to achieve the upper computer and the lower computer between the data transmission and signal transmission. In order to anti-jamming should be designed in its transmission process anti-jamming circuit. In this logic control design, weighing the upper part of the filling machine and liquid filling machine hardware equipment connected to the design of a control box to complete, which includes software and hardware interoperability to realize the logic control, complete the upper part of the machine and the lower part of the signal interaction between the machine to produce filling action. In this filling machine, there are two flows of signals, one is the filling equipment to the computer to process the signals, including the pulse signal from the weighing meter, the filling start and stop valve status signals and quantitative liquid level signal mother. The other is the computer sent to the filling equipment to perform signals, including filling start signal, filling end signal and filling times signal. These actions are accomplished by logical interactions in the control box of the weighing and filling machine.

The control box design of the weighing and filling machine includes three control cards: signal input and output channel control card: ESIA bus control card; power supply card. These three cards are combined together to complete the signal filling start-stop valve (open and close the signal), weighbridge (pulse signal) to the computer between the transfer. In the liquid filling machine, the use of programmable counters / timers 8253 to record the cumulative number of pulses issued by the explosion-proof pound and the frequency of pulses issued. Because the required filling volume is different, sometimes the cumulative number of pulses will be very large, so the choice of two programmable counters / timers 8253 cascade way. Each programmable counter/timer 8253 has three counters/timers, we use one to record the frequency and one to record the number of pulses. Programmable parallel communication interface 8255A designed to become a liquid filling machine equipment and computer between the input and output data interface.

Liquid level signal logic control

Automatic filling scale in order to facilitate the need for error correction, in this filling machine is designed to quantitative filling of the liquid level control signal. When the liquid level reaches the required amount of value, the weighing and filling machine automatically stops filling, filling start-stop valve closed. Completion of this function is the use of photoelectric transistor light-sensitive properties, in the glass level indicator tube is equipped with photoelectric transistor outside, due to the photoelectric transistor outside the sealing of the block with the ring electric wood, when there is a rise in level to the photoelectric transistor and has not yet reached the photoelectric transistor, photoelectric transistor were in the cut-off and conduction state, the output of the voltage characteristics of the different signals through the input, the output channel control card isolation amplification This signal is isolated and amplified by the input and output channel control card, and sent to one of the legs of PA1, PA2 or PA5, PA6 of the A port of the programmable parallel communication interface chip 8255 of the EISA control card. Through the software detection, control the filling start-stop valve action. That is, when the liquid level does not reach the predetermined filling position, the filling start-stop valve is in the open state; when it reaches the predetermined position, the filling start-stop valve is closed.

Liquid filling scale equipment on the photosensitive transistor sensor level signal part, which has been in the light-emitting diode part of the conduction state, when there is no liquid in the liquid level indicator tube, the photosensitive transistor in the state of illumination, its photocurrent is greater than or equal to 1.5mA; liquid level indicator tube there is a liquid, due to the liquid barrier, the photosensitive transistor is in the cut-off state, it is less than or equal to the dark current of 0.8Ma. So we receive the transistor according to the photosensitive photocurrent and dark current size is different at the same time, can make and connected to the resistor to produce different potentials, set poetry a potential comparator and Schmidt circuit with, to distinguish and compare the liquid level in the liquid level indicator tube whether to achieve the quantitative indication. 2.5V regulator LM336 provides LM311 output low level voltage threshold Ut-, regulator power supply is +12V, R6 regulator current limiter. R6 current limiting resistor of the voltage regulator.

Logic Control of Pulse Counter

In the EISA control interface board, the pulse counter is composed of two programmable counters 8253 cascade. The pulse counter is cascaded from counter l of the two programmable counters 8253, and the output OUT of counter 1 of counter 8253A is used as the clock input of counter 1 of programmable counter 8253B.

Logic Control of Frequency Counter

The frequency counter is made up of two programmable counter/timer 8253 cascades. One of them

(8253B) static counter O serves as the timer and the other (8253A) is proudly the counter. Timer and counter of the beginning and end of the action is synchronized by the respective gating signal control, gating signal control and the previous section of the counter gating signal on the synchronization and is the same logic control.

Weighing and filling machine software design

Liquid filling machine software control platform written in C language, compiled in the DOS environment, providing users with a friendly human-machine interface interface, through the interface prompts and users to communicate with the user, so that the user can control their own liquid filling machine action process. The control of this software control interface includes: the control of each filling volume setting; the control of filling times; the control of filling start; the control of filling end; the display of the number of filling pulses and the display of filling frequency.

1. Control of each filling volume setting

Filling quantity is a very important control quantity in the filling experiment, its size is set according to the actual different needs, in this liquid filling machine, the output upper limit frequency of the weighing meter is 1000Hz, the diameter of the weighing module is 20mm, the range of the weighing meter is 3m2/h, the filling fixed-point weighing is chemically 2L/s, the equivalent of the pulse is 0.5mL/pulse, and the setting of the pulse for each filling quantity is 2000 pulses are set for each filling quantity, the change of this quantity should be monitored by the software, and the filling will be ended when the change of the pulse quantity is detected to reach the set value. This filling volume setting is entered through the keyboard, press the F2 key, enter the set pulse value, enter the correct value, through the software detection, automatically carry out the next step of the filling initialization procedure.

2. Control of filling times

We have to assess the size of the filling experiment weighing and filling machine error through a number of measurements, due to the limitations of the size of the workload device, we set the filling for 60 times, every time the filling is completed, the software program automatically makes the number of filling times increase by one, when the number of filling times set up, the end of a filling experiment. In addition, in every completion of a filling, in the absence of the next filling, there is a 10-second interval, waiting for the next filling, this time is controlled by the software.

3. Filling start control

In each experiment, there is a command to start filling, we set the key F3 as the control key to start filling, when we press the F3 key, a filling experiment starts and the filling start-stop valve opens. In the next 59 filling, we do not need to control in the interface, in the process of the experiment, by the software automatically start and close the action.

4. Filling end control

When the set number of filling times, an experiment is completed, the filling start-stop valve is closed and in the absence of a "start filling" signal, the liquid filling machine has been in the working state, or if we want to terminate the experiment, according to the interface prompts us to press the end of the filling button F4, the filling start-stop valve is closed, the filling is completed. If we want to terminate the experiment, according to the prompt of the interface, we can press the key F4 to close the filling valve.

5. Filling pulse number display

In each filling process, due to the computer's application of hardware running speed limitations and software detection of the limitations of the running time, in fact, can not always be the most accurate in the set pulse value to stop filling, filling filling pulse number shows the actual number of filling pulses each time, that is, for the actual amount of filling, but also for the future data processing to provide the basis.

6. Filling frequency display

Filling frequency is the filling rate display, you can also see the filling rate of the dynamic changes in the Jikji, to provide the operator with a simple filling status display interface, but also for the future error correction brings convenience.