CN210514598U - 4 ~ 20mA calibrator - Google Patents
4 ~ 20mA calibrator Download PDFInfo
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- CN210514598U CN210514598U CN201921227104.0U CN201921227104U CN210514598U CN 210514598 U CN210514598 U CN 210514598U CN 201921227104 U CN201921227104 U CN 201921227104U CN 210514598 U CN210514598 U CN 210514598U
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Abstract
The utility model discloses a 4 ~ 20mA calibrator, including shell body subassembly, battery pack, demonstration and keyboard subassembly, circuit subassembly and interface module, battery pack and circuit subassembly fixed mounting are inside the shell body subassembly, demonstration and keyboard subassembly and interface module fixed mounting are on the shell body subassembly, show and keyboard subassembly and interface module and circuit module electricity and be connected, circuit subassembly includes power supply circuit, 485 communication circuit, wiFi circuit, shows and keyboard control circuit, current input circuit, current output circuit and calibrator control circuit; the interface assembly comprises a plurality of paths of 4-20 mA current input interfaces and a plurality of paths of 4-20 mA current output interfaces which are the same in number, the 4-20 mA current input interfaces are connected with the input end of the current input circuit, and the 4-20 mA current output interfaces are connected with the output end of the current output circuit.
Description
Technical Field
The utility model belongs to the technical field of 4 ~ 20mA signal generator, specifically speaking relates to a 4 ~ 20mA calibrator.
Background
The 4-20 mA signal generator is frequently used in the field of measurement and control and belongs to the standard matching of laboratories and check rooms. A4-20 mA signal generator on the market can generate one path of signal intelligently.
A general 4-20 mA signal generator is provided with two signal output ends, namely a positive electrode and a negative electrode, and the positive electrode and the negative electrode of the general 4-20 mA signal generator are respectively connected with two positive and negative signal electrodes of a sensor by leads when the general 4-20 mA signal generator is used. The connection mode of the lead mainly comprises the following steps: the alligator clip, the screw compressing connecting piece, the binding post, the plug and the socket and the like. The connection mode has the advantages that the connection mode is flexible, the lead can be long or short, the sensor can adapt to various sensor structures, the working efficiency is low, the positive and negative leads need to be clearly distinguished during connection, otherwise the sensor is burnt out, and the connection can be poor in conduction after long-term use.
In a convertor station, a sensor with 4-20 mA current is checked by using a protection tester, and the defects are that (1) the tester is large and heavy in size, inconvenient to carry and incapable of being used in a place with a narrow space; (2) the commercial power 220V alternating current is adopted for supplying power, and the commercial power can not be used in places without a 220V alternating current power supply or a power socket; (3) when in use, the connecting wires are time-consuming and labor-consuming, and the equipment is easy to be burnt out by mistake. (4) The multi-channel current output capability is not available, a plurality of sensors cannot be verified simultaneously, and the efficiency is low for occasions with large verification quantity. (5) The device has no multi-path current input capability, and can not measure a plurality of sensors at the same time.
The application number is 2013202867040's chinese patent discloses a direct current signal generator, and this direct current signal generator includes keyboard, controller, display circuit, DA converter, first amplifier, second amplifier and power, can output 4 ~ 20 mA's direct current, and is small, portable, is fit for the field usage, but this direct current signal generator only can produce signal all the way, can't check many sensors simultaneously, and is inefficient to the occasion that the check-up volume is big. Meanwhile, the signal generator is not specially provided for the joint, and the problem of difficult wiring can also exist.
SUMMERY OF THE UTILITY MODEL
Aiming at the defects in the prior art, the utility model provides a 4-20 mA calibrator which has small volume and light weight, is suitable for places with narrow space and is portable; the battery assembly is used for supplying power, and can be used in occasions without commercial power as long as the battery is sufficient in electric quantity; the interface is divided into an input interface and an output interface, so that the connection is convenient, errors are not easy to occur, and equipment cannot be burnt; the multi-channel circuit has the input and output capabilities of multiple circuits, each channel is independent, multiple sensors can be verified simultaneously, and the efficiency is high in the occasion with large verification quantity; a WiFi circuit is arranged, and the calibrator can realize wireless communication; set up 485 communication interface, can with the computer communication, accord with MODBUS agreement.
In order to achieve the above object, the utility model discloses a solution is: a4-20 mA calibrator comprises a shell body assembly, a battery assembly, a display and keyboard assembly, a circuit assembly and an interface assembly, wherein the battery assembly and the circuit assembly are fixedly arranged in the shell body assembly, the display and keyboard assembly and the interface assembly are fixedly arranged on the shell body assembly, the display and keyboard assembly and the interface assembly are electrically connected with the circuit assembly, the battery assembly supplies power for the circuit assembly, the circuit assembly comprises a power supply circuit, a 485 communication circuit, a WiFi circuit, a display and keyboard control circuit, a current input circuit, a current output circuit and a calibrator control circuit, the input end of the power supply circuit is connected with the power supply end of the battery assembly, the power supply circuit outputs a standard voltage source, the transceiving end of the 485 communication circuit is connected with the 485 protocol data transceiving end of the calibrator control circuit, the transceiving end of the WiFi circuit is connected with the WiFi transceiving end of the calibrator control circuit, the control end of the current input circuit is connected with the current input control end of the calibrator control circuit, the control end of the current output circuit is connected with the current output control end of the calibrator control circuit, and the signal transceiving end of the display and keyboard control circuit is connected with the positive and negative signal transceiving end of the first 485 communication circuit; the interface assembly comprises a plurality of paths of 4-20 mA current input interfaces and a plurality of paths of 4-20 mA current output interfaces which are the same in number, the 4-20 mA current input interfaces are connected with the input end of the current input circuit, and the 4-20 mA current output interfaces are connected with the output end of the current output circuit.
Further, the interface module further comprises a charging interface and an RS485 interface, the charging interface is connected with the charging end of the battery module, and the RS485 interface is connected with the positive and negative signal receiving and transmitting ends of the second 485 communication circuit.
Furthermore, the WiFi circuit comprises a WiFi chip, the heavy load end of the WiFi chip is respectively connected with the tenth resistor and the WiFi heavy load end of the calibrator control circuit, the reset end of the WiFi chip is respectively connected with the ninth resistor and the WiFi reset end of the calibrator control circuit, and the other ends of the tenth resistor and the ninth resistor are connected with a voltage source; the power supply end of the WiFi chip is respectively connected with the anode of the eighth capacitor, the anode of the eleventh polar capacitor and a voltage source, the working normal indicating end of the WiFi chip is connected with the base electrode of the first triode, the emitting electrode of the first triode is respectively connected with the sixty resistor and the WiFi working normal indicating end of the calibrator control circuit, the other end of the sixty resistor is connected with the cathode of the first light-emitting diode, the anode of the first light-emitting diode is connected with the voltage source, the connecting indicating end of the WiFi chip is connected with the base electrode of the second triode, the emitting electrode of the second triode is respectively connected with the sixty-one resistor and the WiFi connecting indicating end of the calibrator control circuit, the other end of the sixty-one resistor is connected with the cathode of the second light-emitting diode, the anode of the second light-emitting diode is connected with the voltage source, and the collector electrode of the first triode, and the collector of the second triode, the other end of the eighth capacitor and the negative electrode of the eleventh polar capacitor are grounded.
Furthermore, the current input circuit comprises an A/D conversion chip, five input circuits and one battery input circuit, wherein the power supply end of the A/D conversion chip is respectively connected with the second capacitor, the anode of the seventh polar capacitor, the eighth resistor, the fourth resistor, the fifth resistor, the sixth resistor and the sixty-sixth resistor, the other end of the sixty-sixth resistor is connected with a voltage source, and the other end of the second capacitor and the cathode of the seventh polar capacitor are grounded; the chip selection end of the A/D conversion chip is respectively connected with the A/D conversion chip selection end of the calibrator control circuit and the other end of the eighth resistor, and the clock end of the A/D conversion chip is respectively connected with the A/D conversion clock end of the calibrator control circuit and the other end of the fourth resistor; the serial data signal input end of the A/D conversion chip is respectively connected with the A/D serial data signal output end of the calibration controller circuit and the other end of the fifth resistor, the serial data signal output end of the A/D conversion chip is respectively connected with the A/D serial data signal input end of the calibration controller circuit and the other end of the sixth resistor, the five analog input ends of the A/D conversion chip are respectively connected with the five input circuits, and one analog input end of the A/D conversion chip is connected with one battery input circuit;
the five input circuits are the same, the input circuit comprises an operational amplifier, one analog input end of an A/D conversion chip is respectively connected with the anode of a second polar capacitor, a twenty-first capacitor and a fifty-first resistor, the other end of the fifty-first resistor is respectively connected with the output end of a third operational amplifier, the inverting input end of the third operational amplifier is connected with the output end of the third operational amplifier, the output end of the third operational amplifier is also connected with an eighteenth capacitor, the non-inverting input end of the third operational amplifier is respectively connected with a forty-sixth resistor and a nineteenth capacitor, the other end of the forty-sixth resistor is respectively connected with the other end of the eighteenth capacitor and the forty-first resistor, the other end of the forty-first resistor is respectively connected with the twentieth capacitor, the third resistor and the third end of a third Schottky diode, the second end of the third Schottky diode is connected with a power supply, the other end of the third resistor is connected with the seventh resistor and the positive end of the 4-20 mA current input interface respectively, and the other end of the seventh resistor, the first end of the third Schottky diode and the other end of the twentieth capacitor are grounded;
the battery input circuit comprises an operational amplifier, one path of analog input end of an A/D conversion chip is respectively connected with the anode of an eighth polar capacitor, a third capacitor and a fifty-seventh resistor, the other end of the fifty-seventh resistor is connected with the output end of the eighth operational amplifier, the inverting input end of the eighth operational amplifier is connected with the output end of the eighth operational amplifier, the non-inverting input end of the eighth operational amplifier is respectively connected with the anode of a ninth polar capacitor, the fourth capacitor, the fifty-eighth resistor and the fifty-sixth resistor, the other end of the fifty-sixth resistor is connected with a power supply, the other end of the fifty-eighth resistor, the other end of the fourth capacitor, the cathode of the ninth polar capacitor, the other end of the third capacitor and the cathode of the eighth polar capacitor are grounded.
Furthermore, the current output circuit comprises a D/A converter and a five-way output circuit, the power supply end of the D/A conversion chip is respectively connected with the positive electrode of the seventh capacitor, the positive electrode of the twelfth polar capacitor, the fourteenth resistor, the fifteenth resistor, the sixteenth resistor, the eleventh resistor and the sixty-nine resistor, the other end of the sixty-nine resistor is connected with a voltage source, the other end of the seventh capacitor and the negative electrode of the twelfth polar capacitor are grounded, the reset end of the D/A conversion chip is respectively connected with the D/A conversion end of the calibrator control circuit and the other end of the fourteenth resistor, the synchronous control input end of the D/A conversion chip is respectively connected with the D/A conversion control output end of the calibrator control circuit and the other end of the fifteenth resistor, the clock end of the D/A conversion chip is respectively connected with the D/A conversion clock end of the calibrator control circuit and the other end of the sixteenth resistor, the serial data signal input end of the D/A conversion chip is respectively connected with the serial data signal output end of the calibrator control circuit and the other end of the eleventh resistor, and the five analog signal output ends of the D/A conversion chip are respectively connected with the five output circuits;
the five output circuits are the same, each output circuit comprises an operational amplifier, one analog signal output end of the D/A conversion chip is connected with a seventy-fourth resistor, the other end of the seventy-fourth resistor is respectively connected with a thirty-eighth capacitor, a seventy-seventh resistor and the non-inverting input end of a fifth operational amplifier, the inverting input end of the fifth operational amplifier is respectively connected with a seventy-sixth resistor, a seventy-fifth resistor connected in parallel and one end of a fifth capacitor, the other ends of the seventy-fifth resistor and the fifth capacitor are respectively connected with the emitting electrode and the thirteenth resistor of a third triode, the output end of the fifth operational amplifier is connected with a ninety-fourth resistor, the other end of the ninety-fourth resistor is connected with the base electrode of the third triode, the collector electrode of the third triode is connected with a twelfth resistor, and the other end of the twelfth resistor is connected with a power supply; the other end of the thirteenth resistor is connected with the non-inverting input end of the sixth operational amplifier, the third end of the sixth capacitor and the third end of the eighth Schottky diode respectively, the second end of the eighth Schottky diode is connected with the power supply, the third end of the eighth Schottky diode is further connected with the ninety-ninth resistor, the other end of the ninety-ninth resistor is connected with the positive end of the 4-20 mA current output interface, the inverting input end of the sixth operational amplifier is connected with the output end of the sixth operational amplifier, and the output end of the sixth operational amplifier is further connected with the other end of the seventy-seventh resistor; the other end of the thirty-eighth capacitor, the other end of the seventy-sixth resistor, the other end of the sixth capacitor and the first end of the eighth Schottky diode are grounded.
Further, the display and keyboard control circuit comprises a keyboard circuit, a display and keyboard controller and a display communication circuit, wherein a signal transceiving end of the display communication circuit is connected with a positive and negative signal transceiving end of the first 485 communication circuit, a control end of the display communication circuit is connected with a control end of the display and keyboard controller, a control end of the display circuit is connected with a display control end of the display and keyboard controller, and a control end of the keyboard circuit is connected with a keyboard control end of the display and keyboard controller.
The keyboard circuit comprises keys, a first row of key control ends of the display and keyboard controller are respectively connected with a first resistor, a second key, a fifth key and a sixth key, a second row of key control ends of the display and keyboard controller are respectively connected with a second resistor, a first key, a third key and a fourth key, the other ends of the first resistor and the second resistor are respectively connected with a power supply, the other ends of the first key and the second key are respectively connected with a first row of key control ends of the display and keyboard controller, the other ends of the third key and the fifth key are respectively connected with a second row of key control ends of the display and keyboard controller, and the other ends of the fourth key and the sixth key are respectively connected with a third row of key control ends of the display and keyboard controller.
Furthermore, the display circuit comprises a liquid crystal display, a power supply end of the liquid crystal display is connected with a thirty-second resistor, the other end of the thirty-second resistor is connected with a voltage source, a driving voltage input end of the liquid crystal display is connected with an adjusting end of the adjustable resistor, a positive voltage output end of the liquid crystal display is connected with a thirty-fourth resistor, the other end of the thirty-fourth resistor is connected with a first end of the adjustable resistor, a second end of the adjustable resistor is connected with a thirty-third resistor, and the other end of the thirty-third resistor is grounded; the positive end of a backlight source of the liquid crystal display is respectively connected with the eleventh capacitor, the twelfth capacitor and a voltage source, the negative end of the backlight source of the liquid crystal display is respectively connected with the other ends of the seventeenth resistor and the eleventh capacitor, the other end of the seventeenth resistor is connected with a collector of a fourth triode, a base of the fourth triode is respectively connected with a thirty-fifth resistor and a thirty-sixth resistor, the other end of the thirty-sixth resistor is connected with a backlight control end of a display and keyboard controller, and an emitter of the fourth triode and the other end of the thirty-fifth resistor are grounded;
the parallel command selecting end of the liquid crystal display is respectively connected with the display parallel command controlling end and the eighteenth resistor of the display and keyboard controller, the parallel read-write selecting end of the liquid crystal display is respectively connected with the display parallel read-write controlling end and the twenty-first resistor of the display and keyboard controller, the parallel enabling end of the liquid crystal display is respectively connected with the display parallel enabling end and the nineteenth resistor of the display and keyboard controller, the first data end of the liquid crystal display is respectively connected with the display first data output end and the twenty-second resistor of the display and keyboard controller, the second data end of the liquid crystal display is respectively connected with the display second data output end and the twenty-eighth resistor of the display and keyboard controller, the third data end of the liquid crystal display is respectively connected with the display third data output end and the twenty-eighth resistor of the display and keyboard controller, the fourth data end of the liquid crystal display is respectively connected with the fourth data output end and the twenty-third resistor of the display and keyboard controller, the fifth data end of the liquid crystal display is respectively connected with the fifth data output end and the twenty-ninth resistor of the display and keyboard controller, the sixth data end of the liquid crystal display is respectively connected with the sixth data output end and the twenty-fourth resistor of the display and keyboard controller, the seventh data end of the liquid crystal display is respectively connected with the seventh data output end and the thirty-fourth resistor of the display and keyboard controller, the eighth data end of the liquid crystal display is respectively connected with the eighth data output end and the twenty-fifth resistor of the display and keyboard controller, the first chip selection end of the liquid crystal display is respectively connected with the first chip selection control end and the thirty-first resistor of the display and keyboard controller, the second chip selection end of the liquid crystal display is respectively connected with the second chip selection control end of the display and keyboard controller and the twenty-sixth resistor, the reset end of the liquid crystal display is respectively connected with the tenth capacitor and the twenty-seventh resistor, the other end of the eighteenth resistor, the other end of the nineteenth resistor, the other end of the twentieth resistor, the other end of the twenty-first resistor, the other end of the twenty-second resistor, the other end of the twenty-third resistor, the other end of the twenty-fourth resistor, the other end of the twenty-fifth resistor, the other end of the twenty-sixth resistor, the other end of the twenty-seventh resistor, the other end of the twenty-eighth resistor, the other end of the twenty-ninth resistor, the other end of the thirty resistor and the other end of the thirty-first resistor are connected with the power.
Furthermore, the display communication circuit is a third 485 communication circuit, a signal transceiving end of the third 485 communication circuit is connected with a positive and negative signal transceiving end of the first 485 communication circuit, and a control end of the third 485 communication circuit is connected with a control end of the display and keyboard controller.
Further, the display and keyboard assembly comprises a display screen and keys, wherein the keys comprise a menu key, a confirmation key, a cancel key, an up key and a down key.
The utility model has the advantages that:
(1) the calibrator has small volume and light weight, is suitable for places with narrow space and is portable; the battery assembly is used for supplying power, and can be used in occasions without commercial power as long as the battery is sufficient in electric quantity; the interface is divided into an input interface and an output interface, so that the connection is convenient, errors are not easy to occur, and equipment cannot be burnt; the multi-channel circuit has the input and output capabilities of multiple circuits, each channel is independent, multiple sensors can be verified simultaneously, and the efficiency is high in the occasion with large verification quantity; a WiFi circuit is arranged, and the calibrator can realize wireless communication; set up 485 communication interface, can with the computer communication, accord with MODBUS agreement. .
(2) And the color dot matrix liquid crystal graph is adopted for displaying, the display content is rich and visual, and the human-computer interface is friendly.
Drawings
FIG. 1 is a schematic structural diagram of the calibrator of the present invention;
FIG. 2 is a circuit diagram of the control circuit of the calibrator of the present invention;
FIG. 3 is a WiFi circuit diagram;
FIG. 4 is a circuit diagram of an A/D conversion chip;
FIG. 5 is a circuit diagram of an input circuit;
FIG. 6 is a battery input circuit diagram;
FIG. 7 is a circuit diagram of a D/A conversion chip;
FIG. 8 is a diagram of an output circuit;
FIG. 9 is a circuit diagram of a keyboard;
FIG. 10 is a circuit diagram;
FIG. 11 is a display and keyboard controller circuit;
in the figure: r1-first resistor, R2-second resistor, R3-third resistor, R4-fourth resistor, R5-fifth resistor, R6-sixth resistor, R7-seventh resistor, R8-eighth resistor, R9-ninth resistor, R10-tenth resistor, R11-eleventh resistor, R12-twelfth resistor, R13-thirteenth resistor, R14-fourteenth resistor, R15-fifteenth resistor, R16-sixteenth resistor, R17-seventeenth resistor, R18-eighteenth resistor, R19-nineteenth resistor, R20-twentieth resistor, R21-twenty-first resistor, R22-twenty-second resistor, R23-twenty-third resistor, R24-twenty-fourth resistor, R25-twenty-fifth resistor, R26-twenty-sixth resistor, R27-seventh resistor, r28-twenty-eighth resistor, R29-twenty-ninth resistor, R30-thirty-fourth resistor, R31-thirty-first resistor, R32-thirty-second resistor, R33-thirty-third resistor, R34-thirty-fourth resistor, R35-thirty-fifth resistor, R36-thirty-sixth resistor, R37-thirty-seventh resistor, R38-thirty-eighth resistor, R39-thirty-ninth resistor, R40-forty-fourth resistor, R41-forty-first resistor, R46-forty-sixth resistor, R51-fifty-first resistor, R56-fifty-sixth resistor, R57-fifty-seventh resistor, R58-eighth resistor, R60-sixty resistor, R61-sixty-first resistor, R66-sixty-sixth resistor, R69-sixty-ninth resistor, R74-seventh resistor, r75-seventy-fifth resistor, R76-seventy-sixth resistor, R77-seventy-seventh resistor, R94-ninety-fourth resistor, R99-ninety-ninth resistor, C2-second capacitor, C3-third capacitor, C4-fourth capacitor, C5-fifth capacitor, C6-sixth capacitor, C7-seventh capacitor, C8-eighth capacitor, C10-tenth capacitor, C11-eleventh capacitor, C12-twelfth capacitor, C18-eighteenth capacitor, C19-nineteenth capacitor, C20-twentieth capacitor, C21-twenty-first capacitor, C38-thirty-eighth capacitor, E2-second polar capacitor, E7-seventh polar capacitor, E8-eighth polar capacitor, E9-ninth polar capacitor, E11-eleventh capacitor, E12-twelfth polar capacitor, q1-first triode, Q2-second triode, Q3-third triode, Q4-fourth triode, D3-third Schottky diode, D8-eighth Schottky diode, LED 1-first light-emitting diode, and LED 2-second light-emitting diode.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
as shown in fig. 1, a 4-20 mA calibrator comprises a shell body assembly, a battery assembly, a display and keyboard assembly, a circuit assembly and an interface assembly, wherein the battery assembly and the circuit assembly are fixedly installed inside the shell body assembly, the display and keyboard assembly and the interface assembly are fixedly installed on the shell body assembly, the display and keyboard assembly and the interface assembly are electrically connected with the circuit assembly, the battery assembly supplies power to the circuit assembly, the circuit assembly comprises a power supply circuit, a 485 communication circuit, a WiFi circuit, a display and keyboard control circuit, a current input circuit, a current output circuit and a calibrator control circuit, the input end of the power supply circuit is connected with the power supply end of the battery assembly, the power supply circuit outputs 3.3V voltage required by other circuits, the transceiving end of the 485 communication circuit is connected with the 485 protocol data transceiving end of the calibrator control circuit, the receiving and transmitting end of the WiFi circuit is connected with the WiFi receiving and transmitting end of the calibrator control circuit, the control end of the current input circuit is connected with the current input control end of the calibrator control circuit, the control end of the current output circuit is connected with the current output control end of the calibrator control circuit, and the signal receiving and transmitting end of the display and keyboard control circuit is connected with the positive and negative signal receiving and transmitting ends of the first 485 communication circuit; the interface assembly comprises a plurality of paths of 4-20 mA current input interfaces and a plurality of paths of 4-20 mA current output interfaces which are the same in number, the 4-20 mA current input interfaces are connected with the input end of the current input circuit, and the 4-20 mA current output interfaces are connected with the output end of the current output circuit. The multi-channel circuit input and output capacity is achieved, each channel is independent, multiple sensors can be checked at the same time, the efficiency is high in the occasion with large checking quantity, the interface is divided into the input interface and the output interface, the connection is convenient, errors are not prone to occurring, and equipment cannot be burnt. The battery pack adopts a lithium battery and is normally used in places where electricity is deficient and alternating current power supply is inconvenient.
The 4-20 mA current input interface and the 4-20 mA current output interface are both aviation plugs and sockets, the plugging and unplugging are simple, the current input interface is connected to a signal source, and the current output interface is connected to a load.
Further, the interface module further comprises a charging interface and an RS485 interface, the charging interface is connected with the charging end of the battery module, and the RS485 interface is connected with the positive and negative signal receiving and transmitting ends of the second 485 communication circuit. The shell body assembly is also provided with a power switch which is electrically connected with the power circuit. And the RS485 interface of the calibrator and the computer are connected by using a lead, so that the communication between the calibrator and the computer is realized.
As shown in fig. 2 and fig. 3, the WiFi circuit includes a WiFi chip, a heavy load end of the WiFi chip is connected to the tenth resistor R10 and a WiFi heavy load end of the scaler control circuit respectively, a reset end of the WiFi chip is connected to the ninth resistor R9 and a WiFi reset end of the scaler control circuit respectively, and the other ends of the tenth resistor R10 and the ninth resistor R9 are connected to a voltage source; the power supply end of the WiFi chip is respectively connected with an eighth capacitor C8, the anode of an eleventh polar capacitor and a voltage source, the working normal indication end of the WiFi chip is connected with the base electrode of a first triode Q1, the emitter of a first triode Q1 is respectively connected with a sixty resistor R60 and the WiFi working normal indication end of a calibrator control circuit, the other end of the sixty resistor R60 is connected with the cathode of a first light-emitting diode LED1, the anode of the first light-emitting diode LED1 is connected with the voltage source, the connection indication end of the WiFi chip is connected with the base electrode of a second triode Q2, the emitter of the second triode Q2 is respectively connected with a sixty-first resistor R61 and the WiFi connection indication end of the calibrator control circuit, the other end of the sixty-first resistor R61 is connected with the cathode of a second light-emitting diode LED2, the collector of the second light-emitting diode LED2 is connected with the voltage source, the collector of the first triode Q1, the collector of the second triode Q2, The other terminal of the eighth capacitor C8 and the negative terminal of the eleventh polarized capacitor are grounded. The calibrator is provided with a WiFi module and has a wireless function, electronic equipment such as a computer, a mobile phone and a tablet can be wirelessly connected to the calibrator, the input current or the output current of each path of the calibrator can be checked on the equipment, and the output current of each path can be wirelessly regulated. The device can also store the input current and the output circuit of each path to form a history record, thereby facilitating data management and exchange and realizing wireless remote transmission, wireless modification and wireless remote control of data.
Furthermore, the current input circuit comprises an A/D conversion chip, five input circuits and a battery input circuit. As shown in fig. 2 and 4, the power source terminals of the a/D conversion chip are respectively connected to the second capacitor C2, the positive electrode of the seventh polar capacitor, the eighth resistor R8, the fourth resistor R4, the fifth resistor R5, the sixth resistor, and the sixty-sixth resistor R66, the other end of the sixty-sixth resistor R66 is connected to the voltage source, and the other end of the second capacitor C2 and the negative electrode of the seventh polar capacitor are grounded; the chip selection end of the A/D conversion chip is respectively connected with the A/D conversion chip selection end of the calibrator control circuit and the other end of the eighth resistor R8, and the clock end of the A/D conversion chip is respectively connected with the A/D conversion clock end of the calibrator control circuit and the other end of the fourth resistor R4; the serial data signal input end of the A/D conversion chip is respectively connected with the A/D serial data signal output end of the calibration controller circuit and the other end of the fifth resistor R5, the serial data signal output end of the A/D conversion chip is respectively connected with the A/D serial data signal input end of the calibration controller circuit and the other end of the sixth resistor R6, the five analog input ends of the A/D conversion chip are respectively connected with the five input circuits, and one analog input end of the A/D conversion chip is connected with one battery input circuit.
The five input circuits are the same, taking one of the input circuits as an example, as shown in fig. 5 and 4, the input circuit includes an operational amplifier, one analog input end of the a/D conversion chip is connected to the anode of the second polar capacitor E2, the twenty-first capacitor C21 and the fifty-first resistor R51, the other end of the fifty-first resistor R51 is connected to the output end of the third operational amplifier, the inverting input end of the third operational amplifier is connected to the output end of the third operational amplifier, the output end of the third operational amplifier is further connected to the eighteenth capacitor C18, the non-inverting input end of the third operational amplifier is connected to the forty-sixth resistor R46 and the nineteenth capacitor C19, the other end of the forty-sixth resistor R46 is connected to the other end of the eighteenth capacitor C18 and the forty-first resistor R41, the other end of the forty-first resistor R41 is connected to the twenty-capacitors C20, the twenty capacitors C, The third end of the third resistor R3 and the third end of the third Schottky diode D3 are connected, the second end of the third Schottky diode D3 is connected with a power supply, the other end of the third resistor R3 is connected with the positive end of the seventh resistor R7 and the positive end of the 4-20 mA current input interface respectively, and the other end of the seventh resistor R7, the first end of the third Schottky diode D3 and the other end of the twentieth capacitor C20 are grounded. The 4-20 mA ammeter signal output by the sensor is connected through an aviation socket, input into amplification and filtering for processing to obtain a signal with good signal-to-noise ratio, and then subjected to analog-to-digital conversion and calculation by a calibrator control circuit to obtain a measurement result which is sent to a display and an EEPROM memory.
As shown in fig. 6 and 4, the battery input circuit includes an operational amplifier, one analog input end of the a/D conversion chip is connected to the positive electrode of the eighth polar capacitor E8, the third capacitor C3 and the fifty-seventh resistor R57, the other end of the fifty-seventh resistor R57 is connected to the output end of the eighth operational amplifier, the inverting input end of the eighth operational amplifier is connected to the output end of the eighth operational amplifier, the non-inverting input end of the eighth operational amplifier is connected to the positive electrode of the ninth polar capacitor, the fourth capacitor C4, the fifty-eighth resistor R58 and the fifty-sixth resistor R56, the other end of the fifty-sixth resistor R56 is connected to the power supply, the other end of the fifty-eighth resistor R58, the other end of the fourth capacitor C4, the negative electrode of the ninth polar capacitor, the other end of the third capacitor C3 and the negative electrode of the eighth polar capacitor are grounded.
Furthermore, the current output circuit includes a D/a converter and a five-way output circuit, as shown in fig. 2 and fig. 7, power terminals of the D/a conversion chip are respectively connected to a seventh capacitor C7, an anode of a twelfth polar capacitor, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, an eleventh resistor R11 and a sixty-nine resistor R69, another terminal of the sixty-nine resistor R69 is connected to a voltage source, another terminal of the seventh capacitor C7 and a cathode of the twelfth polar capacitor are grounded, reset terminals of the D/a conversion chip are respectively connected to a D/a conversion reset terminal of the scaler control circuit and another terminal of the fourteenth resistor R14, a synchronization control input terminal of the D/a conversion chip is respectively connected to a D/a conversion control output terminal of the scaler control circuit and another terminal of the fifteenth resistor R15, the clock end of the D/A conversion chip is respectively connected with the D/A conversion clock end of the calibrator control circuit and the other end of the sixteenth resistor R16, the serial data signal input end of the D/A conversion chip is respectively connected with the serial data signal output end of the calibrator control circuit and the other end of the eleventh resistor R11, and the five analog signal output ends of the D/A conversion chip are respectively connected with the five output circuits;
the five output circuits are the same, and one of the output circuits is taken as an example for specific explanation, as shown in fig. 8, the output circuit includes an operational amplifier, one analog signal output terminal of the D/a conversion chip is connected with a seventy-fourth resistor R74, the other end of the seventy-fourth resistor R74 is connected with the thirty-eighth capacitor C38, the seventy-seventh resistor R77 and the non-inverting input terminal of the fifth operational amplifier, the inverting input terminal of the fifth operational amplifier is connected with the seventy-sixth resistor R76, one end of the seventy-fifth resistor R75 and one end of the fifth capacitor C5 which are connected in parallel, the other end of the seventy-fifth resistor R75 and the other end of the fifth capacitor C5 are connected with the emitter of the third triode Q3 and the thirteenth resistor R13, the output terminal of the ninety operational amplifier is connected with the fourth resistor R94, the other end of the ninety-fourth resistor R94 is connected with the base of the third triode Q3, the collector of the third triode Q3 is connected with the twelfth resistor R12, the other end of the twelfth resistor R12 is connected with a power supply; the other end of the thirteenth resistor R13 is respectively connected with the non-inverting input end of the sixth operational amplifier, the third end of the sixth capacitor C6 and the third end of the eighth Schottky diode D8, the second end of the eighth Schottky diode D8 is connected with the power supply, the third end of the eighth Schottky diode D8 is further connected with the ninety ninth resistor R99, the other end of the ninety ninth resistor R99 is connected with the positive end of the 4-20 mA current output interface, the inverting input end of the sixth operational amplifier is connected with the output end of the sixth operational amplifier, and the output end of the sixth operational amplifier is further connected with the other end of the seventy-seventh resistor R77; the other end of the thirty-eighth capacitor C38, the other end of the seventy-sixth resistor R76, the other end of the sixth capacitor C6 and the first end of the eighth Schottky diode D8 are grounded. And the control circuit of the calibrator performs digital-to-analog conversion on the current value obtained by operation according to the current magnitude and the channel number set by a user, and then the current value is processed by an amplifier and a filter to obtain the current with the specified magnitude and is sent to external equipment connected to the aviation socket.
Further, the display and keyboard control circuit comprises a keyboard circuit, a display and keyboard controller and a display communication circuit, wherein a signal transceiving end of the display communication circuit is connected with a positive and negative signal transceiving end of the first 485 communication circuit, a control end of the display communication circuit is connected with a control end of the display and keyboard controller, a control end of the display circuit is connected with a display control end of the display and keyboard controller, and a control end of the keyboard circuit is connected with a keyboard control end of the display and keyboard controller.
As shown in fig. 9 and 11, the keyboard circuit includes keys, a first row of key control ends of the display and keyboard controller are respectively connected to the first resistor R1, the second key, the fifth key and the sixth key, a second row of key control ends of the display and keyboard controller are respectively connected to the second resistor R2, the first key, the third key and the fourth key, the other ends of the first resistor R1 and the second resistor R2 are respectively connected to the power supply, the other ends of the first key and the second key are respectively connected to a first row of key control ends of the display and keyboard controller, the other ends of the third key and the fifth key are respectively connected to a second row of key control ends of the display and keyboard controller, and the other ends of the fourth key and the sixth key are respectively connected to a third row of key control ends of the display and keyboard controller. The first key corresponds to an upward key in the corresponding display and keyboard assembly, the second key corresponds to a confirmation key, the third key corresponds to a downward key, the fourth key is standby, the fifth key corresponds to a cancel key, the sixth key corresponds to a menu key, and the keys are used for menu activation and parameter setting/modification.
As shown in fig. 10 and 11, the display circuit includes a liquid crystal display, a power supply terminal of the liquid crystal display is connected to a thirty-second resistor R32, another terminal of the thirty-second resistor R32 is connected to a voltage source, a driving voltage input terminal of the liquid crystal display is connected to an adjusting terminal of an adjustable resistor, a positive voltage output terminal of the liquid crystal display is connected to a thirty-fourth resistor R34, another terminal of the thirty-fourth resistor R34 is connected to a first terminal of the adjustable resistor, a second terminal of the adjustable resistor is connected to a thirty-third resistor R33, and another terminal of the thirty-third resistor R33 is grounded; the positive electrode end of a backlight source of the liquid crystal display is respectively connected with an eleventh capacitor C11, a twelfth capacitor C12 and a voltage source, the negative electrode end of the backlight source of the liquid crystal display is respectively connected with the other ends of a seventeenth resistor R17 and an eleventh capacitor C11, the other end of a seventeenth resistor R17 is connected with a collector of a fourth triode Q4, the base of the fourth triode Q4 is respectively connected with a thirty-fifth resistor R35 and a thirty-sixth resistor R36, the other end of the thirty-sixth resistor R36 is connected with the backlight control end of a display and keyboard controller, and the emitter of the fourth triode Q4 and the other end of the thirty-fifth resistor R35 are grounded;
the parallel command selecting end of the liquid crystal display is respectively connected with the display parallel command controlling end and the eighteenth resistor R18 of the display and keyboard controller, the parallel read-write selecting end of the liquid crystal display is respectively connected with the display parallel read-write controlling end and the twenty-first resistor R21 of the display and keyboard controller, the parallel enabling end of the liquid crystal display is respectively connected with the display parallel line enabling end and the nineteenth resistor R19 of the display and keyboard controller, the first data end of the liquid crystal display is respectively connected with the display first data output end and the twenty-second resistor R22 of the display and keyboard controller, the second data end of the liquid crystal display is respectively connected with the display second data output end and the twentieth resistor R20 of the display and keyboard controller, the third data end of the liquid crystal display is respectively connected with the display third data output end and the twenty-eighth resistor R28 of the display and keyboard controller, the fourth data terminal of the liquid crystal display is respectively connected with the fourth data output terminal of the display and keyboard controller and the twenty-third resistor R23, the fifth data terminal of the liquid crystal display is respectively connected with the fifth data output terminal of the display and keyboard controller and the twenty-ninth resistor R29, the sixth data terminal of the liquid crystal display is respectively connected with the sixth data output terminal of the display and keyboard controller and the twenty-fourth resistor R24, the seventh data terminal of the liquid crystal display is respectively connected with the seventh data output terminal of the display and keyboard controller and the thirty-fourth resistor R30, the eighth data terminal of the liquid crystal display is respectively connected with the eighth data output terminal of the display and keyboard controller and the twenty-fifth resistor R25, the first chip selection terminal of the liquid crystal display is respectively connected with the first chip selection control terminal of the display and keyboard controller and the thirty-resistor R31, the second chip selection end of the liquid crystal display is respectively connected with the second chip selection control end of the display and keyboard controller and a twenty-sixth resistor R26, the reset end of the liquid crystal display is respectively connected with a tenth capacitor C10 and a twenty-seventh resistor R27, the other end of an eighteenth resistor R18, the other end of a nineteenth resistor R19, the other end of a twentieth resistor R20, the other end of a twenty-first resistor R21, the other end of a twenty-second resistor R22, the other end of a twenty-third resistor R23, the other end of a twenty-fourth resistor R24, the other end of a twenty-fifth resistor R25, the other end of a twenty-sixth resistor R26, the other end of a twenty-seventh resistor R27, the other end of a twenty-eighth resistor R28, the other end of a twenty-ninth resistor R29, the other end of a thirty resistor and the other end of a thirty-eleventh resistor R31 are connected with a power. The lcd is a display screen in the display and keyboard assembly, and a 128 × 64 dot display screen with backlight function keys is adopted. The display screen is used for displaying corresponding contents, such as displaying corresponding menu items and parameter values during menu operation, displaying the numerical values of input current and output current during test starting, and the like.
Furthermore, the display communication circuit is a third 485 communication circuit, a signal transceiving end of the third 485 communication circuit is connected with a positive and negative signal transceiving end of the first 485 communication circuit, and a control end of the third 485 communication circuit is connected with a control end of the display and keyboard controller. The first 485 communication circuit is connected with the third 485 communication circuit through a wire, the content to be displayed is sent to the display and keyboard control circuit through the internal 485 communication bus, the display and keyboard controller receives the data and then carries out conversion to obtain the graph to be displayed, and the graph to be displayed is sent to the LCD display to be displayed on a screen in a dot matrix mode.
After the actions of the keys on the keyboard are detected by the display and keyboard controller, the processing such as filtering and key fetching is carried out, and the results are sent to the control circuit of the calibrator to be processed, so that various parameters set by a user are obtained, or functional programs of the corresponding keys are executed to realize current detection and output.
The above-mentioned embodiments only express the specific embodiments of the present invention, and the description thereof is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention.
Claims (10)
1. The utility model provides a 4 ~ 20mA calibrator which characterized in that: the display and keyboard module and the interface module are electrically connected with the circuit module, the battery module supplies power for the circuit module, the circuit module comprises a power supply circuit, a 485 communication circuit, a WiFi circuit, a display and keyboard control circuit, a current input circuit, a current output circuit and a calibrator control circuit, the input end of the power supply circuit is connected with the power supply end of the battery module, the power supply circuit outputs a standard voltage source, the transceiving end of the 485 communication circuit is connected with the 485 protocol data transceiving end of the calibrator control circuit, the transceiving end of the WiFi circuit is connected with the WiFi transceiving end of the calibrator control circuit, the control end of the current input circuit is connected with the current input control end of the calibrator control circuit, the control end of the current output circuit is connected with the current output control end of the calibrator control circuit, and the signal transceiving end of the display and keyboard control circuit is connected with the positive and negative signal transceiving end of the first 485 communication circuit; the interface assembly comprises a plurality of paths of 4-20 mA current input interfaces and a plurality of paths of 4-20 mA current output interfaces which are the same in number, the 4-20 mA current input interfaces are connected with the input end of the current input circuit, and the 4-20 mA current output interfaces are connected with the output end of the current output circuit.
2. The 4-20 mA calibrator according to claim 1, wherein: the interface assembly further comprises a charging interface and an RS485 interface, the charging interface is connected with the charging end of the battery assembly, and the RS485 interface is connected with the positive and negative signal receiving and transmitting ends of the second channel 485 communication circuit.
3. The 4-20 mA calibrator according to claim 1, wherein: the WiFi circuit comprises a WiFi chip, the heavy-load end of the WiFi chip is respectively connected with a tenth resistor and the WiFi heavy-load end of the calibrator control circuit, the reset end of the WiFi chip is respectively connected with a ninth resistor and the WiFi reset end of the calibrator control circuit, and the other ends of the tenth resistor and the ninth resistor are connected with a voltage source; the power supply end of the WiFi chip is respectively connected with the anode of the eighth capacitor, the anode of the eleventh polar capacitor and a voltage source, the working normal indicating end of the WiFi chip is connected with the base electrode of the first triode, the emitting electrode of the first triode is respectively connected with the sixty resistor and the WiFi working normal indicating end of the calibrator control circuit, the other end of the sixty resistor is connected with the cathode of the first light-emitting diode, the anode of the first light-emitting diode is connected with the voltage source, the connecting indicating end of the WiFi chip is connected with the base electrode of the second triode, the emitting electrode of the second triode is respectively connected with the sixty-one resistor and the WiFi connecting indicating end of the calibrator control circuit, the other end of the sixty-one resistor is connected with the cathode of the second light-emitting diode, the anode of the second light-emitting diode is connected with the voltage source, and the collector electrode of the first triode, and the collector of the second triode, the other end of the eighth capacitor and the negative electrode of the eleventh polar capacitor are grounded.
4. The 4-20 mA calibrator according to claim 1, wherein: the current input circuit comprises an A/D conversion chip, five input circuits and one battery input circuit, wherein the power supply end of the A/D conversion chip is respectively connected with a second capacitor, the anode of a seventh polar capacitor, an eighth resistor, a fourth resistor, a fifth resistor, a sixth resistor and a sixty-sixth resistor, the other end of the sixty-sixth resistor is connected with a voltage source, and the other end of the second capacitor and the cathode of the seventh polar capacitor are grounded; the chip selection end of the A/D conversion chip is respectively connected with the A/D conversion chip selection end of the calibrator control circuit and the other end of the eighth resistor, and the clock end of the A/D conversion chip is respectively connected with the A/D conversion clock end of the calibrator control circuit and the other end of the fourth resistor; the serial data signal input end of the A/D conversion chip is respectively connected with the A/D serial data signal output end of the calibration controller circuit and the other end of the fifth resistor, the serial data signal output end of the A/D conversion chip is respectively connected with the A/D serial data signal input end of the calibration controller circuit and the other end of the sixth resistor, the five analog input ends of the A/D conversion chip are respectively connected with the five input circuits, and one analog input end of the A/D conversion chip is connected with one battery input circuit;
the five input circuits are the same, the input circuit comprises an operational amplifier, one analog input end of an A/D conversion chip is respectively connected with the anode of a second polar capacitor, a twenty-first capacitor and a fifty-first resistor, the other end of the fifty-first resistor is respectively connected with the output end of a third operational amplifier, the inverting input end of the third operational amplifier is connected with the output end of the third operational amplifier, the output end of the third operational amplifier is also connected with an eighteenth capacitor, the non-inverting input end of the third operational amplifier is respectively connected with a forty-sixth resistor and a nineteenth capacitor, the other end of the forty-sixth resistor is respectively connected with the other end of the eighteenth capacitor and the forty-first resistor, the other end of the forty-first resistor is respectively connected with the twentieth capacitor, the third resistor and the third end of a third Schottky diode, the second end of the third Schottky diode is connected with a power supply, the other end of the third resistor is connected with the seventh resistor and the positive end of the 4-20 mA current input interface respectively, and the other end of the seventh resistor, the first end of the third Schottky diode and the other end of the twentieth capacitor are grounded;
the battery input circuit comprises an operational amplifier, one path of analog input end of an A/D conversion chip is respectively connected with the anode of an eighth polar capacitor, a third capacitor and a fifty-seventh resistor, the other end of the fifty-seventh resistor is connected with the output end of the eighth operational amplifier, the inverting input end of the eighth operational amplifier is connected with the output end of the eighth operational amplifier, the non-inverting input end of the eighth operational amplifier is respectively connected with the anode of a ninth polar capacitor, the fourth capacitor, the fifty-eighth resistor and the fifty-sixth resistor, the other end of the fifty-sixth resistor is connected with a power supply, the other end of the fifty-eighth resistor, the other end of the fourth capacitor, the cathode of the ninth polar capacitor, the other end of the third capacitor and the cathode of the eighth polar capacitor are grounded.
5. The 4-20 mA calibrator according to claim 1, wherein: the current output circuit comprises a D/A converter and a five-way output circuit, the power supply end of a D/A conversion chip is respectively connected with a seventh capacitor, the anode of a twelfth polar capacitor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, an eleventh resistor and a sixty-nine resistor, the other end of the sixty-nine resistor is connected with a voltage source, the other end of the seventh capacitor and the cathode of the twelfth polar capacitor are grounded, the reset end of the D/A conversion chip is respectively connected with the D/A conversion reset end of a calibrator control circuit and the other end of the fourteenth resistor, the synchronous control input end of the D/A conversion chip is respectively connected with the D/A conversion control output end of the calibrator control circuit and the other end of the fifteenth resistor, the clock end of the D/A conversion chip is respectively connected with the D/A conversion clock end of the calibrator control circuit and the other end of the sixteenth resistor, the serial data signal input end of the D/A conversion chip is respectively connected with the serial signal output end of the calibrator control circuit and the other end of the eleventh resistor, and the five analog signal output ends of the D/A conversion chip are respectively connected with the five output circuits;
the five output circuits are the same, each output circuit comprises an operational amplifier, one analog signal output end of the D/A conversion chip is connected with a seventy-fourth resistor, the other end of the seventy-fourth resistor is respectively connected with a thirty-eighth capacitor, a seventy-seventh resistor and the non-inverting input end of a fifth operational amplifier, the inverting input end of the fifth operational amplifier is respectively connected with a seventy-sixth resistor, a seventy-fifth resistor connected in parallel and one end of a fifth capacitor, the other ends of the seventy-fifth resistor and the fifth capacitor are respectively connected with the emitting electrode and the thirteenth resistor of a third triode, the output end of the fifth operational amplifier is connected with a ninety-fourth resistor, the other end of the ninety-fourth resistor is connected with the base electrode of the third triode, the collector electrode of the third triode is connected with a twelfth resistor, and the other end of the twelfth resistor is connected with a power supply; the other end of the thirteenth resistor is connected with the non-inverting input end of the sixth operational amplifier, the third end of the sixth capacitor and the third end of the eighth Schottky diode respectively, the second end of the eighth Schottky diode is connected with the power supply, the third end of the eighth Schottky diode is further connected with the ninety-ninth resistor, the other end of the ninety-ninth resistor is connected with the positive end of the 4-20 mA current output interface, the inverting input end of the sixth operational amplifier is connected with the output end of the sixth operational amplifier, and the output end of the sixth operational amplifier is further connected with the other end of the seventy-seventh resistor; the other end of the thirty-eighth capacitor, the other end of the seventy-sixth resistor, the other end of the sixth capacitor and the first end of the eighth Schottky diode are grounded.
6. The 4-20 mA calibrator according to claim 1, wherein: the display and keyboard control circuit comprises a keyboard circuit, a display and keyboard controller and a display communication circuit, wherein a signal receiving and transmitting end of the display communication circuit is connected with a positive signal receiving and transmitting end and a negative signal receiving and transmitting end of the first 485 communication circuit, a control end of the display communication circuit is connected with a control end of the display and keyboard controller, a control end of the display circuit is connected with a display control end of the display and keyboard controller, and a control end of the keyboard circuit is connected with a keyboard control end of the display and keyboard controller.
7. The 4-20 mA calibrator according to claim 6, wherein: the keyboard circuit comprises keys, a first row of key control ends of a display and keyboard controller are respectively connected with a first resistor, a second key, a fifth key and a sixth key, a second row of key control ends of the display and keyboard controller are respectively connected with a second resistor, a first key, a third key and a fourth key, the other ends of the first resistor and the second resistor are respectively connected with a power supply, the other ends of the first key and the second key are respectively connected with a first row of key control ends of the display and keyboard controller, the other ends of the third key and the fifth key are respectively connected with a second row of key control ends of the display and keyboard controller, and the other ends of the fourth key and the sixth key are respectively connected with a third row of key control ends of the display and keyboard controller.
8. The 4-20 mA calibrator according to claim 6, wherein: the display circuit comprises a liquid crystal display, a power supply end of the liquid crystal display is connected with a thirty-second resistor, the other end of the thirty-second resistor is connected with a voltage source, a driving voltage input end of the liquid crystal display is connected with an adjusting end of an adjustable resistor, a positive voltage output end of the liquid crystal display is connected with a thirty-fourth resistor, the other end of the thirty-fourth resistor is connected with a first end of the adjustable resistor, a second end of the adjustable resistor is connected with a thirty-third resistor, and the other end of the thirty-third resistor is grounded; the positive end of a backlight source of the liquid crystal display is respectively connected with the eleventh capacitor, the twelfth capacitor and a voltage source, the negative end of the backlight source of the liquid crystal display is respectively connected with the other ends of the seventeenth resistor and the eleventh capacitor, the other end of the seventeenth resistor is connected with a collector of a fourth triode, a base of the fourth triode is respectively connected with a thirty-fifth resistor and a thirty-sixth resistor, the other end of the thirty-sixth resistor is connected with a backlight control end of a display and keyboard controller, and an emitter of the fourth triode and the other end of the thirty-fifth resistor are grounded;
the parallel command selecting end of the liquid crystal display is respectively connected with the display parallel command controlling end and the eighteenth resistor of the display and keyboard controller, the parallel read-write selecting end of the liquid crystal display is respectively connected with the display parallel read-write controlling end and the twenty-first resistor of the display and keyboard controller, the parallel enabling end of the liquid crystal display is respectively connected with the display parallel enabling end and the nineteenth resistor of the display and keyboard controller, the first data end of the liquid crystal display is respectively connected with the display first data output end and the twenty-second resistor of the display and keyboard controller, the second data end of the liquid crystal display is respectively connected with the display second data output end and the twenty-eighth resistor of the display and keyboard controller, the third data end of the liquid crystal display is respectively connected with the display third data output end and the twenty-eighth resistor of the display and keyboard controller, the fourth data end of the liquid crystal display is respectively connected with the fourth data output end and the twenty-third resistor of the display and keyboard controller, the fifth data end of the liquid crystal display is respectively connected with the fifth data output end and the twenty-ninth resistor of the display and keyboard controller, the sixth data end of the liquid crystal display is respectively connected with the sixth data output end and the twenty-fourth resistor of the display and keyboard controller, the seventh data end of the liquid crystal display is respectively connected with the seventh data output end and the thirty-fourth resistor of the display and keyboard controller, the eighth data end of the liquid crystal display is respectively connected with the eighth data output end and the twenty-fifth resistor of the display and keyboard controller, the first chip selection end of the liquid crystal display is respectively connected with the first chip selection control end and the thirty-first resistor of the display and keyboard controller, the second chip selection end of the liquid crystal display is respectively connected with the second chip selection control end of the display and keyboard controller and the twenty-sixth resistor, the reset end of the liquid crystal display is respectively connected with the tenth capacitor and the twenty-seventh resistor, the other end of the eighteenth resistor, the other end of the nineteenth resistor, the other end of the twentieth resistor, the other end of the twenty-first resistor, the other end of the twenty-second resistor, the other end of the twenty-third resistor, the other end of the twenty-fourth resistor, the other end of the twenty-fifth resistor, the other end of the twenty-sixth resistor, the other end of the twenty-seventh resistor, the other end of the twenty-eighth resistor, the other end of the twenty-ninth resistor, the other end of the thirty resistor and the other end of the thirty-first resistor are connected with the power.
9. The 4-20 mA calibrator according to claim 6, wherein: the display communication circuit is a third 485 communication circuit, the signal transceiving end of the third 485 communication circuit is connected with the positive and negative signal transceiving end of the first 485 communication circuit, and the control end of the third 485 communication circuit is connected with the control end of the display and keyboard controller.
10. The 4-20 mA calibrator according to claim 1, wherein: the display and keyboard assembly comprises a display screen and keys, wherein the keys comprise a menu key, a confirmation key, a cancel key, an up key and a down key.
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| CN201920759695 | 2019-05-24 | ||
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110320487A (en) * | 2019-05-24 | 2019-10-11 | 中国南方电网有限责任公司超高压输电公司昆明局 | One kind 4~20mA calibration device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110320487A (en) * | 2019-05-24 | 2019-10-11 | 中国南方电网有限责任公司超高压输电公司昆明局 | One kind 4~20mA calibration device |
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