CN105784062A

CN105784062A - Method and device for detecting material level in material bin

Info

Publication number: CN105784062A
Application number: CN201610228127.8A
Authority: CN
Inventors: 汪玉坤; 赫健; 徐少川; 刘宇; 娄莹; 王玉昆
Original assignee: University of Science and Technology Liaoning USTL
Current assignee: University of Science and Technology Liaoning USTL
Priority date: 2016-04-13
Filing date: 2016-04-13
Publication date: 2016-07-20
Anticipated expiration: 2036-04-13
Also published as: CN105784062B

Abstract

The invention relates to a method and device for detecting the material level in a material bin. The device is characterized in that a measuring cable is arranged at the central axis of the circular metal material bin and is parallel with and insulated from the metal bin wall, the measuring cable and the metal bin wall form a parallel plate capacitor, and the capacitance of the parallel plate capacitor is the total capacitance CX of a material bin capacitive sensor; an electronic oscillating circuit is used to form a primary instrument, an RS-485 bus differential drive function is used to transmit a pulse sequence signal between the primary instrument and a secondary instrument, the change of the CX is converted into the corresponding pulse sequence signal and remotely transmitted to the secondary instrument, and the second instrument measures the cycle T of the pulse sequence signal; the material level L1 is obtained. The device is simple in overall structure, easy to implement, fast in detection, high in accuracy, simple to mount, low in cost, convenient for a user to use, free of a mechanical moving device, small in primary instrument size, light, and long in service life.

Description

The detection method of thing position height and device in a kind of material bin

Technical field

The present invention relates to material storage for field, particularly relate to detection method and the device of thing position height in a kind of material bin.

Background technology

In industrial and agricultural production activity, under many circumstances can spent material reserving chamber, such as the various liquid of chemical industry Or solids feed bin, the crude stockpile storehouse in petroleum recovering factory, bulk cement storage bin etc. during concrete production.These things Material has solid, powder, liquid, also has that conduct electricity and non-conductive.In process of production, it is desirable to grasp thing at any time The number of material in feed bin, the most simple method is exactly can the height of thing position in detectable substance feed bin at any time.Conventional thing position Detecting instrument chattering type, ultrasonic type, Weight type, float-ball type etc..The shortcoming of contact level meter is to detect continuous print Thing position；Although ultrasonic type level meter energy continuous detecting thing position, but its accuracy of detection is by material top surface shape in material bin Impact, the foam of liquid surface also influences whether its accuracy of detection；Weight type level meter is only suitable for measuring the height of solids position, And having mechanical movement means, structure is complicated, runs noise big, the shortcomings such as energy consumption is big；Float-ball type level meter is only applicable to measure The height of liquids position.

Summary of the invention

For overcoming the deficiencies in the prior art, it is an object of the invention to provide the detection method of thing position height in a kind of material bin And device, improve detection speed, accuracy, easy to use.

For achieving the above object, the present invention is achieved through the following technical solutions:

The detection method of thing position height in a kind of material bin, comprises the following steps:

A is provided with a measurement cable at the central axis of circular metal material bin, measures cable parallel with metal silo wall, and Insulating with metal silo wall, measure cable and form a parallel plate capacitor with metal silo wall, the capacitance of parallel plate capacitor is material Storehouse capacitance sensor total capacitance C_X；

B utilize electronic oscillating circuit form primary instrument, utilize RS-485 bus differential drive function, primary instrument with Transmission pulse sequence signal between secondary meter, by C_XChange be converted into corresponding pulse sequence signal teletransmission to secondary instrument Table, the cycle T of pulse sequence signal measured by secondary meter；

C calculates material bin capacitance sensor total capacitance Cx:

c_{x} = c_{0} + c_{1} + c_{2}

= C_{0} + \frac{2 π [ϵ_{0} L_{0} + (ϵ_{1} - ϵ_{0}) L_{1}]}{\ln \frac{D}{d}} - - - (1)

In formula (1): C₀The fixing stray capacitance not changed with the change of material in storehouse for capacitance；C₁For material top Electric capacity with air as medium；C₂For the electric capacity with material as medium；L₀Height within material bin, is definite value；D is feed bin Diameter, d be measure cable diameter, L₁Height for thing position；ε₀It is dielectric constant of air, ε₁It it is material dielectric constant；L₁Send out During changing, C_XChange therewith, L₁With C_XIt is directly proportional linear relationship, records C_XValue, the height L of available thing position₁；

L_{1} = \frac{L_{0} * (T - T_{e})}{T_{f} - T_{e}} - - - (2)

In formula (2): L0 is the height within material bin, it it is definite value；Te is pulse period during material bin hole capital after selling all securities, by hole capital after selling all securities Time adjust and obtain, be the lower limit of pulse period；Tf is material bin material pulse period when buying securities with all one's capital, material adjust when buying securities with all one's capital Arrive, be the upper limit of pulse period；T is the cycle of the pulse train of detection in real time, Te≤T≤Tf, as T=Te, and L1=0, thing Feed bin is empty, and as T=Tf, L1=L0, material bin is full；

D sets material lower limit alarming value, material upper limit alarm value and material bin completely protection value, by RS-232 interface and upper Position machine exchange data；After recording thing position height, by numeral method thing place value.

The detection device of thing position height in a kind of material bin, including measure cable, mounting flange, primary instrument circuit board, Primary instrument, the signal is far passed cable, tensioner, insulator, secondary meter, set primary instrument circuit board, once in primary instrument Instrument is connected with mounting flange, and the center of mounting flange is fixed one and measured cable, measures cable and insulate with mounting flange, surveys Amount cable and metal silo wall one capacitance sensor of composition of material bin, measure a cable pole plate as capacitance sensor, Connecting primary instrument circuit board by wire, the metal silo wall of material bin is as another pole plate of capacitance sensor, by leading Line connects primary instrument circuit board, and the lower end connection measuring cable has insulator, insulator to be connected with tensioner one end, tensioner The other end is fixed on material bin bottom center；Primary instrument is connected by the signal is far passed cable with secondary meter.

Described measurement cable surface, with insulating barrier, uses when measuring conductive material thing position.

Described primary instrument circuit board is made up of electronic multivibrator and driver U2, and electronic multivibrator includes Gate circuit U1A, gate circuit U1B, resistance R1, resistance R2, resistance R1 mono-terminates the input of gate circuit U1A, and gate circuit U1A's is defeated Go out end to be connected with resistance R2 one end, the input of gate circuit U1B, the output termination capacitance sensor CX input of gate circuit U1B End, the 3 input DI selecting the common port of 1 switch SW3_1, driver U2,3 select 1 switch SW3_1 to select to compensate electric capacity C1 or compensation Electric capacity C2 or do not select, in order to control the scope of primary instrument output signal frequency；The resistance R1 other end, the resistance R2 other end, Capacitor CX outfan, the compensation electric capacity C1 other end, the other end of compensation electric capacity C2 connect together, and form electronics multi-harmonic-oscillations Device, its output signal frequency is:

F_{O} = \frac{1}{2.2 R_{1} (C_{X} + C)} - - - (3)

In formula (3), C is for compensating electric capacity, and signal is exported by the outfan of gate circuit U1B, and sends into the input of driver U2 DI, through the AB bus of driver U2, delivers to secondary meter by output conversion socket Jout by electrical pulse sequence signal, transmission Distance is less than 1200 meters；

Described secondary meter includes CPU U1, input socket JIN, pulsed signal device U4, display driver U2, shows Showing device U3, power supply, Simple key board, CPU U1, under the driving of software, receives the pulse signal that primary instrument transmits, it is achieved data Gather, data process, data show, Keyboard management, and bound is reported to the police, material fills it up with protection and communication function；

Particular circuit configurations is: the accessory power outlet Jout of primary instrument is by the input socket JIN of bus with secondary meter Being connected, the input socket JIN of secondary meter is connected in the AB bus of pulsed signal device U4, pulsed signal device U4's Output RO is connected to the P35 pin of CPU U1, data acquisition function；P10, P11, P12 pin of CPU U1 is coupled with On the pin of LOAD, CLK and DIN of display driver U2, DG0, DG1, DG2, DG3 pin of display driver U2 is coupled with On DG1, DG2, DG3, DG4 pin of display U3, the position completing display drives；The SGA of display driver U2, SGB, SGC, SGD, SGE, SGF, SGG, SGP, Iset pin is received on power supply through 10K resistance R2, completes display function；The P14 of CPU U1, P15, P16, P17 pin is coupled with on the Simple key board of tetra-buttons of MODE, RL, SET, OK composition, completes alert data, whole Given data function is set；The P00 pin of CPU U1 receives one end of resistance R3, the base of another termination audion Q1 of resistance R3 Pole, is driven buzzer BEEP by audion Q1, completes sound alarm function；The P01 pin of CPU U1 receives one end of resistance R5, The other end of resistance R5 receives the base stage of audion Q2, audion Q2 drive relay R AY1, and the normally closed of relay R AY1 is touched Point SW1 and SW2 No. 5 and No. 6 contact pins extractions by socket J-SP, seal in charging control circuit, complete material and fill it up with protection Function；P30, P31 of CPU U1 receives R1OUT, T1IN pin of communication level translator U5, and T1OUT, R1IN of U5 receive The 2 of socket communication JCOM, on 3 pins, the communication function with host computer is completed.

Compared with prior art, the invention has the beneficial effects as follows:

1. device overall structure is simply easily achieved, and speed is fast, accuracy is high, installation is simple, low cost in detection, and user makes With convenient.

2. mechanical telecontrol equipment, primary instrument volume is little, lightweight, and service life is long.

3. in secondary meter, use CPU, belong to an intelligent embedded system, be possible not only to detection, display Work, it is also possible to bound alarming value is set flexibly, storehouse completely protection value is set, it is also possible to complete the communication with host computer, real Existing data exchange work.

4. the algorithm that the data handling procedure of the inventive method uses is simple, calculates speed fast, and accuracy is high.

Accompanying drawing explanation

Fig. 1 is the principle schematic of the detection method of thing position height in material bin.

Fig. 2 is primary instrument electrical schematic diagram.

Fig. 3 is secondary meter electrical schematic diagram.

Fig. 4 is the detection device application schematic diagram in the non-conductive material of powdery of thing position height in material bin.

Fig. 5 is the detection device application schematic diagram in liquid conduction material of thing position height in material bin.

Fig. 6 is secondary meter control flow chart.

In Fig. 4, Fig. 5: 1-measures cable 2-mounting flange 3-primary instrument circuit board 4-primary instrument shell 5-the signal is far passed cable 6-tensioner 7-insulator 8-insulating barrier.

Detailed description of the invention

Below in conjunction with Figure of description, the present invention is described in detail, it should be noted that the enforcement of the present invention does not limits In following embodiment.

See Fig. 1-Fig. 3, Fig. 6, the detection method of thing position height in a kind of material bin, comprise the following steps:

C calculates material bin capacitance sensor total capacitance Cx:

\begin{matrix} c_{x} = c_{0} + c_{1} + c_{2} \\ = C_{0} + \frac{2 π [ϵ_{0} L_{0} + (ϵ_{1} - ϵ_{0}) L_{1}]}{l n \frac{D}{d}} \end{matrix} - - - (1)

L_{1} = \frac{L_{0} * (T - T_{e})}{T_{f} - T_{e}} - - - (2)

Seeing Fig. 4, Fig. 5, the detection device of thing position height in material bin, including measuring cable 1, mounting flange 2, primary instrument Circuit board 3, primary instrument, the signal is far passed cable 5, tensioner 6, insulator 7, secondary meter, set primary instrument in primary instrument Circuit board 3, primary instrument is connected with mounting flange 2, and the center of mounting flange 2 is fixed one and measured cable 1, measures cable 1 Insulate with mounting flange 2, measure metal silo wall one capacitance sensor of composition of cable 1 and material bin, measure cable 1 as electricity Holding a pole plate of sensor, connect primary instrument circuit board 3 by wire, the metal silo wall of material bin is as capacitance sensor Another pole plate, by wire connect primary instrument circuit board 3, measure cable 1 lower end connect have insulator 7, insulator 7 Being connected with tensioner 6 one end, tensioner 6 other end is fixed on material bin bottom center；Primary instrument and secondary meter are by letter Number teletransmission cable 5 connects.Measure cable 1 surface with insulating barrier 8, the use when measurement conductive material thing position.

Seeing that Fig. 2, primary instrument circuit board are made up of electronic multivibrator and driver U2, electronic multivibrator includes Gate circuit U1A, gate circuit U1B, resistance R1, resistance R2, resistance R1 mono-terminates the input of gate circuit U1A, and gate circuit U1A's is defeated Go out end to be connected with resistance R2 one end, the input of gate circuit U1B, the output termination capacitance sensor CX input of gate circuit U1B End, the 3 input DI selecting the common port of 1 switch SW3_1, driver U2,3 select 1 switch SW3_1 to select to compensate electric capacity C1 or compensation Electric capacity C2 or do not select, in order to control the scope of primary instrument output signal frequency；The resistance R1 other end, the resistance R2 other end, Capacitor CX outfan, the compensation electric capacity C1 other end, the other end of compensation electric capacity C2 connect together, and form electronics multi-harmonic-oscillations Device, its output signal frequency is:

F_{O} = \frac{1}{2.2 R_{1} (C_{X} + C)} - - - (3)

In formula (3), C is for compensating electric capacity, and signal is exported by the outfan of gate circuit U1B, and sends into the input of driver U2 DI, through the AB bus of driver U2, delivers to secondary meter by output conversion socket Jout by electrical pulse sequence signal, transmission Distance is less than 1200 meters；Primary instrument electronic device detail list is listed in subordinate list 1.

See that Fig. 3, secondary meter include CPU U1, input socket JIN, pulsed signal device U4, display driver U2, show Showing device U3, power supply, Simple key board, CPU U1, under the driving of software, receives the pulse signal that primary instrument transmits, it is achieved data Gather, data process, data show, Keyboard management, and bound is reported to the police, material fills it up with protection and communication function；

Particular circuit configurations is: the accessory power outlet Jout of primary instrument is by the input socket JIN of bus with secondary meter Being connected, the input socket JIN of secondary meter is connected in the AB bus of pulsed signal device U4, pulsed signal device U4's Output RO is connected to the P35 pin of CPU U1, data acquisition function；P10, P11, P12 pin of CPU U1 is coupled with On the pin of LOAD, CLK and DIN of display driver U2, DG0, DG1, DG2, DG3 pin of display driver U2 is coupled with On DG1, DG2, DG3, DG4 pin of display U3, the position completing display drives；The SGA of display driver U2, SGB, SGC, SGD, SGE, SGF, SGG, SGP, Iset pin is received on power supply through 10K resistance R2, completes display function；The P14 of CPU U1, P15, P16, P17 pin is coupled with on the Simple key board of tetra-buttons of MODE, RL, SET, OK composition, completes alert data, whole Given data function is set；The P00 pin of CPU U1 receives one end of resistance R3, the base of another termination audion Q1 of resistance R3 Pole, is driven buzzer BEEP by audion Q1, completes sound alarm function；The P01 pin of CPU U1 receives one end of resistance R5, The other end of resistance R5 receives the base stage of audion Q2, audion Q2 drive relay R AY1, and the normally closed of relay R AY1 is touched Point SW1 and SW2 No. 5 and No. 6 contact pins extractions by socket J-SP, seal in charging control circuit, complete material and fill it up with protection Function；P30, P31 of CPU U1 receives R1OUT, T1IN pin of communication level translator U5, and T1OUT, R1IN of U5 receive The 2 of socket communication JCOM, on 3 pins, the communication function with host computer is completed.Secondary meter electronic device detail list is at subordinate list 2 In list.

When the present invention applies, primary instrument is installed on material bin top, and material bin height is generally 15-20 rice.Secondary instrument Table is installed in night shift room or control room, uses four core shielded cables (the signal is far passed cable) between primary instrument and secondary meter Transmission power supply and signal, wherein both threads is used for transmitting power supply, and another both threads differential signal transmission, in order to ensure that instrument is reliable Work, the length connecting cable between primary instrument and secondary meter not can exceed that 1200 meters.

Seeing Fig. 4, the device that in material bin, the detection method of thing position height uses is applied to the bulk water of concrete mixing plant In hopper dredger, the thing position height of cement in monitoring material bin, detection device using method is as follows:

Scale zero is calibrated, and in the case of material bin hole capital after selling all securities, to instrument power supply, presses two buttons of MODE and OK about simultaneously About 3 seconds, then decontrol the two button simultaneously, if now secondary meter display shows " 0000 ", then zero point is adjusted successfully. Otherwise, repeat the above steps, until secondary meter display shows " 0000 ".

Full scale is calibrated, and in material bin, charging is to the height full close to storehouse, and leaves stopping charging after certain surplus, Stand about 10 minutes, press two buttons of MODE and SET about about 3 seconds simultaneously, then decontrol the two button simultaneously, now two The data that secondary instrument display shows are the actual height of thing position.Complete to the work of this meter confirmation, can normally employ. If it is required, keyboard to set up upper and lower limit alarm point data can be passed through, set storehouse and completely protect point data.

As it is shown in figure 5, the device that in a kind of material bin, the detection method of thing position height uses is applied to have conductive characteristic Liquid material bin in, monitoring conducting liquid thing position height time, owing to the material in material bin is conducting liquid, use Middle measurement cable 1 surface insulating barrier to be had 8, it is ensured that measure and can not have contacting of electricity between cable 1 and metal silo wall.

The invention have the advantage that

Subordinate list 1 primary instrument electronic device detail list

Sequence number	Title	Type and spec	Encapsulation	Code name in circuit	Quantity
						1	Integrated circuit	HCF4009	SOIC14	U1	1
2	Integrated circuit	MAX487	SOIC8	U2	1
						3	Chip-R	560K	0603	R1	1
4	Chip-R	56k	0603	R2	1
						5	Patch capacitor	56P	0603	C1	1
6	Patch capacitor	100p	0603	C2	1
						7	3 select 1 switch	DIP_4	DIP8	SW3_1	1
8	Socket	JST-4	CH2.0-4	Jout	1

。

Subordinate list 2 secondary meter electronic device detail list

Claims

1. a detection method of material level height in a material bin, is characterized in that, comprises the following steps:

a. There is a measuring cable on the central axis of the circular metal material bin. The measuring cable is parallel to the metal bin wall and insulated from the metal bin wall. The measuring cable and the metal bin wall form a parallel plate capacitance. The parallel plate capacitance The capacitance is the total capacitance C _X of the capacitance sensor of the material bin;

b Utilize the electronic oscillating circuit to form a primary instrument, use the differential drive function of RS-485 bus, transmit the pulse sequence signal between the primary instrument and the secondary instrument, convert the change of C _X into the corresponding pulse sequence signal and send it to the secondary Meter, the secondary meter measures the period T of the pulse train signal;

c Calculate the total capacitance Cx of the capacitive sensor of the material bin:

\begin{matrix} {c c}_{x x} = = {c c}_{00} + + {c c}_{11} + + {c c}_{22} \\ = = {C C}_{00} + + \frac{22 π π [[{ϵ ϵ}_{00} {L L}_{00} + + (({ϵ ϵ}_{11} - - {ϵ ϵ}_{00})) {L L}_{11}]]}{ln ln \frac{D D.}{d d}} \end{matrix} - - - - - - ((11))

In the formula (1): C ₀ is the fixed stray capacitance whose capacitance does not change with the change of the material in the warehouse; C ₁ is the capacitance on the upper part of the material with air as the medium; C ₂ is the capacitance with the material as the medium; L ₀ is The height inside the material bin is a fixed value; D is the diameter of the bin, d is the diameter of the measuring cable, L ₁ is the height of the material level; ε ₀ is the dielectric constant of air, ε ₁ is the dielectric constant of the material; L When ₁ changes, C _X changes accordingly, L ₁ and C _X are in a proportional linear relationship, and the height L ₁ of the material level can be obtained by measuring the value of C _X ;

{L L}_{11} = = \frac{{L L}_{00} * * ((T T - - {T T}_{e e}))}{{T T}_{f f} - - {T T}_{e e}} - - - - - - ((22))

In the formula (2): L0 is the height inside the material bin, which is a fixed value; Te is the pulse cycle when the material bin is empty, which is obtained from the setting when the empty bin is empty, and is the lower limit of the pulse cycle; Tf is the pulse cycle when the material bin is full , obtained by setting when the material bin is full, is the upper limit of the pulse cycle; T is the cycle of the pulse sequence detected in real time, Te≤T≤Tf, when T=Te, L1=0, the material bin is empty, when T=Tf , L1=L0, the material bin is full;

d Set the material lower limit alarm value, material upper limit alarm value and material bin full protection value, exchange data with the host computer through the RS-232 interface; after measuring the material level height, display the material level value through the digital tube.

2. The detection device for the height of a material level in a material bin realizing the detection method of claim 1 is characterized in that it comprises a measuring cable, a mounting flange, a primary meter circuit board, a primary meter, a signal remote transmission cable, Tensioners, insulators, and secondary instruments. The primary instrument is equipped with a circuit board for the primary instrument. The primary instrument is connected to the mounting flange. A measuring cable is fixed at the center of the mounting flange. The measuring cable is insulated from the mounting flange. The wire and the metal bin wall of the material bin form a capacitive sensor. The measuring cable is used as a plate of the capacitive sensor, and is connected to the primary instrument circuit board through the wire. The metal bin wall of the material bin is used as the other plate of the capacitive sensor. On the circuit board of the primary instrument, the lower end of the measuring cable is connected to an insulator, the insulator is connected to one end of the tensioner, and the other end of the tensioner is fixed at the center of the bottom of the material bin; the primary instrument and the secondary instrument are connected through a signal remote transmission cable.

3. A detection device for the height of a material level in a material bin according to claim 2, wherein the measuring cable has an insulating layer on its surface and is used when measuring the material level of a conductive material.

4. The detection device for the height of a material level in a material bin according to claim 2, wherein the primary instrument circuit board is composed of an electronic multivibrator and a driver U2, and the electronic multivibrator includes a gate Circuit U1A, gate circuit U1B, resistor R1, resistor R2, one end of resistor R1 is connected to the input end of gate circuit U1A, the output end of gate circuit U1A is connected to one end of resistor R2, and the input end of gate circuit U1B, and the output end of gate circuit U1B Connect to the CX input terminal of the capacitive sensor, the common terminal of the 3-to-1 switch SW3_1, and the input terminal DI of the driver U2. The 3-to-1 switch SW3_1 selects the compensation capacitor C1 or compensation capacitor C2 or not to control the range of the output signal frequency of the primary instrument The other end of the resistor R1, the other end of the resistor R2, the output end of the capacitor CX, the other end of the compensation capacitor C1, and the other end of the compensation capacitor C2 are connected together to form an electronic multivibrator, and its output signal frequency is:

{F f}_{O o} = = \frac{11}{2.2 2.2 {R R}_{11} (({C C}_{X x} + + C C))} - - - - - - ((33))

In formula (3), C is the compensation capacitor. The signal is output from the output terminal of the gate circuit U1B and sent to the input terminal DI of the driver U2. After passing through the AB bus of the driver U2, the electric pulse sequence signal is sent to the second terminal through the output conversion socket Jout Secondary meter, the transmission distance is not more than 1200 meters.

5. The detection device for the height of a material level in a material bin according to claim 2, wherein the secondary instrument comprises a CPU U1, an input socket JIN, a pulse signal receiver U4, a display driver U2, a display U3, power supply, simple keyboard, CPU U1, driven by software, receives the pulse signal from the instrument once, and realizes data collection, data processing, data display, keyboard management, upper and lower limit alarm, material full protection and communication functions;

The specific circuit structure is: the output socket Jout of the primary instrument is connected to the input socket JIN of the secondary instrument through the bus, the input socket JIN of the secondary instrument is connected to the AB bus of the pulse signal receiver U4, and the output RO of the pulse signal receiver U4 Connect to the P35 pin of the CPU U1 to complete the data acquisition function; the P10, P11, and P12 pins of the CPU U1 are respectively connected to the LOAD, CLK, and DIN pins of the display driver U2, and the DG0, DG1, and DG2 of the display driver U2 , DG3 pins are respectively connected to the DG1, DG2, DG3, DG4 pins of the display U3 to complete the bit drive of the display; the SGA, SGB, SGC, SGD, SGE, SGF, SGG, SGP, Iset pins of the display driver U2 Connect to the power supply through the 10K resistor R2 to complete the display function; the P14, P15, P16, and P17 pins of the CPU U1 are respectively connected to the simple keyboard composed of four buttons of MODE, RL, SET, and OK to complete the alarm data and setting data. The P00 pin of the CPU U1 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the base of the transistor Q1, and the buzzer BEEP is driven by the transistor Q1 to complete the sound alarm function; the P01 pin of the CPU U1 is connected to To one end of the resistor R5, the other end of the resistor R5 is connected to the base of the transistor Q2, and the relay RAY1 is driven by the transistor Q2, and the normally closed contacts SW1 and SW2 of the relay RAY1 are drawn out through pins 5 and 6 of the socket J-SP , into the feeding control circuit in series to complete the material filling protection function; P30 and P31 of the CPU U1 are connected to the R1OUT and T1IN pins of the communication level converter U5, and the T1OUT and R1IN of U5 are connected to the 2 and 2 of the communication socket JCOM 3 pins, to complete the communication function with the host computer.