Portable testing device for comparing three-bit BCD code digital display instrument

Abstract

The utility model discloses a portable testing device for comparing a three-bit BCD code digital display instrument. The portable testing device comprises a power supply conversion module, a pulse generation module, first to third pulse counting modules, first to third decoding driving modules, first to third digital display modules, and first to third voltage comparison circuits. The output end of the power supply conversion module is connected with a pulse generation module, first to third pulse counting modules and first to third decoding driving modules, the pulse generation module is connected with the first pulse counting module, the second pulse counting module is connected with the third pulse counting module, the ith pulse counting module is connected with the ith decoding driving module, and the ith decoding driving module is connected with the ith decoding driving module. The ith decoding driving module is connected with the ith digital display module and the ith voltage comparison circuit, the three voltage comparison circuits are cascaded in sequence, and i = 1, 2 or 3. According to the utility model, the data detection accuracy of the instrument is ensured, and the risk of production misoperation caused by abnormal display of the pulling speed is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of electronic circuits, and in particular relates to a portable testing device for comparing a three-digit BCD code digital display instrument. Background Art

[0002] In the steelmaking and continuous casting process, billet drawing speed detection is an important measurement process for measuring production. Therefore, the digital display instrument used to display the billet drawing speed in real time also needs to be focused on. The instrument input is a 24V electrical signal in the three-digit 8421BCD encoding method, and the display is a decimal number of ones, tens, and hundreds. The maximum display is 999 and the minimum display is 000. At present, there is no corresponding verification or calibration specification for this type of instrument to guide calibration, and the metrology verification agency cannot determine the measurement accuracy of the instrument. Summary of the invention

[0003] Purpose of the utility model: In order to solve the problems existing in the above-mentioned prior art, the utility model provides a portable test device for comparing three-digit BCD code digital display instruments.

[0004] The technical solution of the utility model: The utility model provides a portable test device for comparing three-digit BCD code digital display instruments, characterized by a power conversion module, a pulse generation module, first to third pulse counting modules, first to third decoding drive modules, first to third digital display modules, and first to third voltage comparison circuits;

[0005] The output end of the power conversion module is connected to the pulse generating module, the first to third pulse counting modules and the first to third decoding driving modules, the pulse generating module is connected to the first pulse counting module, the first pulse counting module is connected to the second pulse counting module, the second pulse counting module is connected to the third pulse counting module, the i-th pulse counting module is connected to the i-th decoding driving module, the i-th decoding driving module is connected to the i-th digital display module and the i-th voltage comparison circuit, and the three voltage comparison circuits are cascaded in sequence, i=1, 2, 3.

[0006] Furthermore, the power conversion module includes an LM7805 chip, a first and a second capacitor, a first resistor and a first light-emitting diode; the COMMON end of the LM7805 chip is grounded, the LINE VOLTAGE is an input end connected to a 24V power supply and the positive electrode of the first capacitor, and the negative electrode of the first capacitor is grounded; the VREG end of the LM7805 chip is an output end connected to the positive electrode of the second capacitor and one end of the first resistor; the other end of the first resistor is connected to the positive electrode of the first light-emitting diode, and the negative electrode of the first light-emitting diode and the negative electrode of the second capacitor are grounded.

[0007] Furthermore, the pulse generating module includes a second and a third resistor, a sliding resistor, a third and a fourth capacitor, a second light-emitting diode and a NE555 chip, the power supply pin of the NE555 chip is connected to the output end of the power conversion module, the reset pin is connected to the output end of the power conversion module and one end of the second resistor, the other end of the second resistor is connected to one end of the sliding resistor and the discharge pin of the NE555 chip, the other end of the sliding resistor is connected to the trigger pin of the NE555 chip, the threshold pin and the positive electrode of the third capacitor, the control voltage pin of the NE555 chip is connected to the positive electrode of the fourth capacitor, the output end of the NE555 chip is connected to one end of the third resistor and the first pulse counting module, the other end of the third resistor is connected to the positive electrode of the second light-emitting diode, the negative electrode of the third capacitor, the negative electrode of the fourth capacitor, the grounding end of the NE555 chip and the negative electrode of the second light-emitting diode are all grounded.

[0008] Furthermore, the three pulse counting modules have the same structure, and all include a CD40192 chip, a dip switch, and a lockless switch; the dip switch is a 4-position dip switch, and the input pins of the dip switch are all connected to the output end of the power conversion module, and the input pins are respectively connected to the P0, P1, P2, and P3 pins of the CD40192 chip; the lockless switch is a six-pin lockless switch with two rows of pins, and the voltage input pin of the lockless switch is connected to the output end of the power conversion module, and the middle pin of any row of the lockless switch is connected to the PL pin of the CD40192 core. pin, the ground pin of the lockless switch is grounded; the CPD pin of the CD40192 chip is connected to the output end of the power conversion module, the O0, O1, O2, and O3 pins of the CD40192 chip are 8421BCD code output ends connected to the corresponding pulse counting modules, the MR pin of the CD40192 chip is grounded, the CPU pin of the first pulse counting module is connected to the pulse generating module, the TCU pin is connected to the CPU pin of the second pulse counting module, and the TCU pin of the second pulse counting module is connected to the CPU pin of the third pulse counting module.

[0009] Furthermore, the three decoding and driving modules have the same structure and all include a CD4511 chip. The DA, DB, DC, and DD pins of the CD4511 chip are connected to the 8421BCD code input terminals of the decoding and driving module and are connected to the corresponding pulse counting module and the corresponding voltage comparison circuit. The EL pin of the CD4511 chip is grounded. The BI and LT pins of the CD4511 chip are connected to the output terminal of the power conversion module. The OA, OB, OC, OD, OE, OF, and OG pins of the CD4511 chip are connected to the corresponding digital display module.

[0010] Furthermore, they all include a 7-segment common cathode digital tube and a fourth resistor, the A, B, C, D, E, F, and G pins of the 7-segment common cathode digital tube are respectively connected to the OA, OB, OC, OD, OE, OF, and OG pins of the corresponding decoding drive module, the CK pin of the 7-segment common cathode digital tube is connected to one end of the fourth resistor, and the other end of the fourth resistor is grounded.

[0011] Furthermore, the three voltage comparison circuits each include first to fourth comparators, fifth to eighth resistors and third to sixth light-emitting diodes, the first to fourth comparators correspond one to one with the third to sixth light-emitting diodes and the fifth to eighth resistors; the output end of the comparison is connected to the cathode of the corresponding light-emitting diode, the anode of the light-emitting diode is connected to one end of the corresponding resistor, and the other end of the resistor is connected to the voltage VCC; the in-phase input ends of the first to fourth comparators are respectively connected to the DA, DB, DC, and DD pins of the CD4511 chip, and the reverse input ends are all grounded; the first voltage comparison circuit also includes ninth and tenth resistors, one ends of the ninth and tenth resistors are both connected to the reverse input end of the first comparison in the first voltage comparison circuit, the other end of the ninth resistor is connected to the voltage VCC, and the other end of the tenth resistor is grounded.

[0012] Beneficial effects: The utility model designs a portable testing device which can automatically compare the display of a BCD code digital display instrument. By connecting the device to a BCD digital display instrument, the instrument can be automatically compared online on a regular basis, thereby ensuring the accuracy of the instrument's data detection, reducing the risk of production misoperation due to abnormal pulling speed display, and solving the problem that the BCD code digital display instrument cannot be compared online. While ensuring the accuracy and reliability of the display instrument, it also provides a solution for calibrating this type of instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of this embodiment;

[0014] Figure 2 is a circuit diagram of a power conversion module;

[0015] Figure 3 This is the circuit diagram of the pulse generation module;

[0016] Figure 4 This is the waveform diagram of the 5V square wave signal output by the pulse generation module;

[0017] Figure 5 This is the circuit diagram of the pulse counting module;

[0018] Figure 6 This is the circuit diagram of the lockless switch;

[0019] Figure 7 It is the circuit diagram of the digital display module and the decoding drive module; Figure 8 is a structural diagram of a voltage comparison circuit;

[0020] Fig. 9 2 is the overall circuit diagram of this embodiment. DETAILED DESCRIPTION

[0021] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0022] like Figure 1 As shown, this embodiment provides a portable test device for comparing three-digit BCD code digital display instruments, which utilizes a power conversion module, a pulse generation module, first to third pulse counting modules, first to third decoding drive modules, first to third digital display modules, and first to third voltage comparison circuits to form a test device that can preset data.

[0023] First, use the LM7805 three-terminal voltage regulator chip and peripheral capacitors, resistors, and light-emitting diodes to form a power conversion module, and use the commonly used 24VDC power supply to output a stable 5V fixed voltage as the power supply for subsequent chips. See the circuit diagram Figure 2 shown.

[0024] Figure 2 VCC in the middle is a common 24VDC power supply; C1 and C2 are 100μF capacitors, which are mainly used to stabilize the input and output voltages; U1 is a LM7805 chip, the left pin (LINE VOLTAGE) is the input terminal, connected to a 24V power supply; the middle pin (COMMON) is the ground pin; the right pin is the output pin, which outputs a stable 5V voltage to power subsequent chips; the resistor R1 (1kΩ) and the light-emitting diode LED1 series circuit is an output visualization auxiliary circuit, and the light-emitting diode is always on when the circuit operates normally. After simulation testing, the output voltage is kept stable at 5V (subsequent power supply VDD).

[0025] The pulse output circuit (Schmitt trigger circuit) is composed of NE555 timer chip and corresponding peripheral resistors, capacitors and sliding resistors. The output cycle is stable and the amplitude is 5V square wave pulse signal. See the circuit diagram Figure 3 As shown, the output square wave pulse is Figure 4 shown.

[0026] Figure 3U16 is the NE555 chip; VDD is connected to the output probe 1 position of the power conversion module (5V); the chip VCC pin is the chip power supply pin; the GND pin is grounded; RST is the reset pin, which is usually connected to a high level during normal operation; the DIS pin is the discharge pin, and the discharge circuit is composed of an adjustable resistor R3 (20kΩ) and a capacitor C3 (1μF); CON is the control voltage pin, and the capacitor C4 (0.1μF) is connected to the circuit to ensure the stability of the control voltage; the THR pin is the threshold pin, which is also the input of the 1# voltage comparator inside the 555 chip. This pin and 2 / 3VDD are connected to the 1# voltage comparator together; the TRI pin is the trigger pin, which is also the input of the 2# voltage comparator inside the 555 chip. This pin and 1 / 3VDD are connected to the input of the 2# voltage comparator together; OUT is the output terminal, and the output terminal is connected in series with a resistor R5 (100Ω) and a light-emitting diode LED2. When the circuit is working normally, the output is Figure 4 Channel A of the oscilloscope displays a square wave signal with an amplitude of 5V. The light-emitting diode flashes periodically with the square wave signal, and the simulation test signal output is stable.

[0027] The 8421BCD code counting circuit is composed of CD40192 chip, peripheral DIP switch and lock-free switch. After adding the square wave pulse output by NE555, the 8421BCD data signal with preset data is output. See the circuit diagram Figure 5 shown.

[0028] Figure 5 U2 in the figure is the CD40192 chip. When the set pin PL (11) is connected to a high level, the clear pin MR (14) is connected to a low level, and the count-down pin CPD (4) is connected to a high level, the chip performs addition counting. The count pulse is connected by the count-up pin CPU (5), and the count pulse input is the output (OUT) of the NE555 chip. When the set pin PL (11) is connected to a low level, the switch S2 moves upward, and the other pins remain unchanged. At this time, the initial count data of the chip is introduced from the counter, that is, Figure 4 In order to perform the count-up function, the switch S2 needs to be moved downward (the downward movement is to restore the high level (5V) action) and connected to a high level. At this time, the count-up starts from the set end. The structure of S2 is as follows Figure 6As shown, pin 1 is connected to a 5V high level, pin 3 is grounded, and pin 2 is connected to pin 11 of the CD40192 chip. When S2 is on, the S1 dial switch indicates that the data is decimal 5 (binary 0101). At this time, the initial data of the chip is preset to 5. When the switch S2 is down, the counting starts from 5. The output terminals of the chip U2 are O0 (3), O1 (2), O2 (6), and O3 (7), which are output to the input terminals of the CD4511 chip in the form of high and low level groups. The carry output terminal TCU (12) is connected to the add count pin CPU (5) of the next CD40192 chip U5. When the ones digit is full, the tens digit automatically advances by 1, and the same applies to the hundreds digit.

[0029] The CD4511 chip, the external common cathode digital tube, and the resistor form the code drive module and the digital display module circuit, decode the 8421BCD code output by the 40192 chip, and display the decoded code. See the circuit diagram Figure 7 shown.

[0030] Figure 7 U3 is a CD4511 decoding chip, and U4 is a 7-segment common cathode digital tube. When the chip performs decoding work normally, the lamp test pin LT (3) and the blanking pin BI (4) are connected to a high level, and the latch control pin EL (5) is connected to a low level to transmit data normally. DA (7), DB (1), DC (2), and DD (6) are 8421BCD code inputs, which are the O0, O1, O2, and O3 outputs of the 40192 chip. The chip outputs 7 segments of data: OA, OB, OC, OD, OE, OF, and OG. This output is connected to the U4 common cathode digital tube ABCDEFG to display the decoded data. The digital tube CK end is connected in series with the current limiting resistor R4 (100Ω) to ground.

[0031] The LM339 chip, peripheral resistors, and light-emitting diodes form a voltage comparison circuit, which converts the TTL level output by the 40192 chip into an HTL level through a voltage comparator and connects it to a BCD digital display instrument. See the circuit diagram Figure 8 shown.

[0032] The four voltage comparators U13A, U13B, U13C, and U13D in the figure use the LM339 chip; R8 (24k) and R9 (1k) are voltage divider resistors; the input terminals 5, 7, 9, and 11 of the four voltage comparators are connected to the output terminals of the 40192 chip: O0, O1, O2, and O3, respectively. By comparing with the voltage after voltage division, the 5VTTL level is converted and output to the 24VHTL level. The output terminals 2, 1, 14, and 13 of the voltage comparator are connected to the 1, 2, 4, and 8 weighted positions of the BCD digital display instrument respectively; R10, R11, R13, and R12 (all 1k) are connected in series with the light-emitting diodes of their respective voltage comparators as a visual auxiliary circuit, which can indirectly prove the consistency of the output data with the data displayed on the digital tube. The voltage conversion circuit for the tens and hundreds digits is the same Figure 8 The units voltage conversion circuit.

[0033] The overall circuit diagram of this embodiment is as follows Fig. 9 As shown, the working process of the circuit of this embodiment is:

[0034] The power conversion module is composed of LM7805 three-terminal voltage regulator chip and peripheral capacitors, resistors, and light-emitting diodes, which can output a stable 5V fixed voltage from the commonly used 24V power supply for subsequent chip power supply.

[0035] 2. Use NE555 timer chip and corresponding peripheral resistors, capacitors, and adjustable resistors to form a pulse generating circuit, which can output a square wave pulse signal with a stable period and an amplitude of 5V;

[0036] 3. Use CD40192 chip, external DIP switch and lock-free switch to form 8421BCD code counting circuit, add and count the square wave pulse output by 555, and output 8421BCD data signal with preset data;

[0037] 4. Use CD4511 chip, external common cathode digital tube and resistor to form decoding and digital display circuit, decode the 8421BCD code output by 40192 chip, and display the decoded code;

[0038] 5. Use the LM339 chip, peripheral resistors, and light-emitting diodes to form a voltage comparison circuit, convert the TTL level output by the 40192 chip into an HTL level through a voltage comparator, and connect it to a BCD digital display instrument;

[0039] 6. When the device is running, the digital tube display mode is to automatically accumulate from 099, and different three-digit data can also be preset, and accumulate from the preset data, so as to compare with the BCD digital display instrument to determine the accuracy of the instrument. The connection relationship between this embodiment and the BCD digital display instrument during specific operation is: U13A output (pin 2) is connected to the A position corresponding to the 8421 code of the unit digit of the BCD instrument wiring terminal, U13B output (pin 1) is connected to the B position corresponding to the 8421 code of the unit digit of the BCD instrument wiring terminal, U13C output (pin 14) is connected to the C position corresponding to the 8421 code of the unit digit of the BCD instrument wiring terminal, U13D output (pin 13) is connected to the D position corresponding to the 8421 code of the unit digit of the BCD instrument wiring terminal, and the following two groups are connected to the tens and hundreds corresponding to the BCD instrument wiring terminals in this way.

[0040] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A portable test device for comparing three-digit BCD code digital display instruments, characterized in that: It includes a power conversion module, a pulse generation module, first to third pulse counting modules, first to third decoding drive modules, first to third digital display modules, and first to third voltage comparison circuits; The output end of the power conversion module is connected to the pulse generating module, the first to third pulse counting modules and the first to third decoding driving modules, the pulse generating module is connected to the first pulse counting module, the first pulse counting module is connected to the second pulse counting module, the second pulse counting module is connected to the third pulse counting module, the i-th pulse counting module is connected to the i-th decoding driving module, the i-th decoding driving module is connected to the i-th digital display module and the i-th voltage comparison circuit, and the three voltage comparison circuits are cascaded in sequence, i=1, 2, 3.

2. A portable test device for comparing three-digit BCD code digital display instruments according to claim 1, characterized in that: The power conversion module includes an LM7805 chip, a first and a second capacitor, a first resistor and a first light-emitting diode; the COMMON end of the LM7805 chip is grounded, the LINE VOLTAGE is an input end connected to a 24V power supply and the positive electrode of the first capacitor, and the negative electrode of the first capacitor is grounded; the VREG end of the LM7805 chip is an output end connected to the positive electrode of the second capacitor and one end of the first resistor; the other end of the first resistor is connected to the positive electrode of the first light-emitting diode, and the negative electrode of the first light-emitting diode and the negative electrode of the second capacitor are grounded.

3. A portable test device for comparing three-digit BCD code digital display instruments according to claim 1, characterized in that: The pulse generating module comprises a second and a third resistor, a sliding resistor, a third and a fourth capacitor, a second light-emitting diode and a NE555 chip. The power supply pin of the NE555 chip is connected to the output end of the power conversion module, the reset pin is connected to the output end of the power conversion module and one end of the second resistor, the other end of the second resistor is connected to one end of the sliding resistor and the discharge pin of the NE555 chip, the other end of the sliding resistor is connected to the trigger pin of the NE555 chip, the threshold pin and the positive electrode of the third capacitor, the control voltage pin of the NE555 chip is connected to the positive electrode of the fourth capacitor, the output end of the NE555 chip is connected to one end of the third resistor and the first pulse counting module, the other end of the third resistor is connected to the positive electrode of the second light-emitting diode, the negative electrode of the third capacitor, the negative electrode of the fourth capacitor, the grounding end of the NE555 chip and the negative electrode of the second light-emitting diode are all grounded.

4. A portable test device for comparing three-digit BCD code digital display instruments according to claim 1, characterized in that: The three pulse counting modules have the same structure, and all include a CD40192 chip, a dip switch, and a lockless switch; the dip switch is a 4-bit dip switch, the input pins of the dip switch are all connected to the output end of the power conversion module, and the output pins are respectively connected to the P0, P1, P2, and P3 pins of the CD40192 chip; the lockless switch is a six-pin lockless switch with two rows of pins, the voltage input pin of the lockless switch is connected to the output end of the power conversion module, the middle pin of any row of the lockless switch is connected to the PL pin of the CD40192 core, and the ground pin of the lockless switch is grounded; the CPD pin of the CD40192 chip is connected to the output end of the power conversion module, the O0, O1, O2, and O3 pins of the CD40192 chip are 8421BCD code output ends connected to the corresponding pulse counting modules, the MR pin of the CD40192 chip is grounded, the CPU pin of the first pulse counting module is connected to the pulse generating module, the TCU pin is connected to the CPU pin of the second pulse counting module, and the TCU pin of the second pulse counting module is connected to the CPU pin of the third pulse counting module.

5. A portable test device for comparing three-digit BCD code digital display instruments according to claim 1, characterized in that: The three decoding drive modules have the same structure and all include a CD4511 chip. The DA, DB, DC, and DD pins of the CD4511 chip are connected to the 8421BCD code input terminals of the decoding drive module and are connected to the corresponding pulse counting module and the corresponding voltage comparison circuit. The EL pin of the CD4511 chip is grounded. The BI and LT pins of the CD4511 chip are connected to the output terminal of the power conversion module. The OA, OB, OC, OD, OE, OF, and OG pins of the CD4511 chip are connected to the corresponding digital display module.

6. A portable test device for comparing three-digit BCD code digital display instruments according to claim 5, characterized in that: The three digital display modules have the same structure and all include a 7-segment common cathode digital tube and a fourth resistor. The A, B, C, D, E, F, and G pins of the 7-segment common cathode digital tube are respectively connected to the OA, OB, OC, OD, OE, OF, and OG pins of the corresponding decoding drive module. The CK pin of the 7-segment common cathode digital tube is connected to one end of the fourth resistor, and the other end of the fourth resistor is grounded.

7. A portable test device for comparing three-digit BCD code digital display instruments according to claim 5, characterized in that: The three voltage comparison circuits all include first to fourth comparators, fifth to eighth resistors and third to sixth light-emitting diodes, the first to fourth comparators correspond one to one with the third to sixth light-emitting diodes and the fifth to eighth resistors; the output end of the comparison is connected to the cathode of the corresponding light-emitting diode, the anode of the light-emitting diode is connected to one end of the corresponding resistor, and the other end of the resistor is connected to the voltage VCC, the in-phase input ends of the first to fourth comparators are respectively connected to the DA, DB, DC, and DD pins of the CD4511 chip, and the reverse input ends are all grounded, the first voltage comparison circuit also includes ninth and tenth resistors, one ends of the ninth and tenth resistors are both connected to the reverse input end of the first comparison in the first voltage comparison circuit, the other end of the ninth resistor is connected to the voltage VCC, and the other end of the tenth resistor is grounded.

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