CN206638727U

CN206638727U - A kind of passive electric current loop measurement instrument of 4 20mA two-wire systems

Info

Publication number: CN206638727U
Application number: CN201720221921.XU
Authority: CN
Inventors: 张赫
Original assignee: RUIPU SANYUAN METER CO Ltd BEIJING
Current assignee: RUIPU SANYUAN METER CO Ltd BEIJING
Priority date: 2017-03-08
Filing date: 2017-03-08
Publication date: 2017-11-14
Anticipated expiration: 2027-03-08

Abstract

The utility model discloses a kind of passive electric current loop measurement instrument of 4 20mA two-wire systems, it includes two-wire system input terminal；Two-wire system input terminal is connected with gathering the current sampling circuit of current loop current signal to be measured；Current sampling circuit divides two-way, it is connected all the way by the current signal collected to be converted into the current conversion circuit of voltage signal with performing the A/D convertor circuit of analog-to-digital conversion, then A/D convertor circuit is connected by IIC universal serial bus with single-chip microcomputer, and another way is connected with from current loop collected current energy to be measured and the collection of energy of supply voltage that is transformed to supply needed for power consuming circuit normal work using circuit；Collection of energy using circuit is current conversion circuit, A/D convertor circuit and single-chip microcomputer provide electric energy.The utility model can not only show loop current value, can also be shown the magnitude of physical quantity representated by loop current value by changing to set, and it does not need extra power supply at work, can be connected in current loop and use for a long time, practical.

Description

A kind of passive electric current loop measurement instrument of 4-20mA two-wire systems

Technical field

A kind of passive electric current loop measurement instrument of 4mA-20mA two-wire systems is the utility model is related to, is to be related to one specifically Kind series connection is accessed in various 4mA-20mA current loops to be measured to loop current, can show loop current value and loop electricity The instrument of measurand value representated by flow valuve.

Background technology

In industry spot, the electricity in current loop can be easily and timely shown because of 4mA-20mA electric current loops metering system Size is flowed, and reflects the measurand value representated by loop current, therefore it is still widely used in industry so far In the various occasions at scene.

A kind of fairly simple implementation practices of 4mA-20mA electric current loop metering systems are, by universal ammeter be serially connected with by Directly loop current value is read in test in the current loop of survey, and is conversed as needed according further to loop current value Its related physical value to be represented.But it can be found that universal ammeter is not easy to be connected to for a long time from actual implement In current loop, the good corresponding magnitude of physical quantity of conversion can not be directly displayed out, and in the electric current of some crucial production procedures In loop application, because the interruption of production procedure does not allow, therefore the limitation that can not arbitrarily cut off circuit circulation is greatly made The about application of ammeter.In addition, the online series connection test of this loop current need it is extra power supply is set, application with It is inconvenient in terms of maintenance.

Utility model content

The purpose of this utility model is to provide a kind of 4-20mA two-wire systems passive electric current loop measurement instrument, and it can not only show Loop current value is shown, can also be shown the magnitude of physical quantity representated by loop current value by changing to set, and it is in work As when do not need extra power supply, can be connected in current loop and use for a long time, it is practical.

To achieve these goals, the utility model employs following technical scheme：

A kind of passive electric current loop measurement instrument of 4-20mA two-wire systems, it is characterised in that：It includes receiving 4mA-20mA inputs The two-wire system input terminal of electric current；Two-wire system input terminal connects with gathering the current sampling circuit of current loop current signal to be measured Connect；Current sampling circuit divides two-way, passes through the current conversion circuit that the current signal collected is converted into voltage signal all the way It is connected with the A/D convertor circuit for performing analog-to-digital conversion, then A/D convertor circuit is connected by IIC universal serial bus with single-chip microcomputer, another Lu Yucong current loop collected current energy to be measured come be transformed to supply power consuming circuit normal work needed for voltage collection of energy Connected using circuit；Collection of energy using circuit is current conversion circuit, A/D convertor circuit and single-chip microcomputer provide electric energy.

The utility model has the advantages that：

1st, the utility model can not only show after measurement has been carried out to the loop current of 4mA-20mA current loops to be measured Loop current value is shown, can also be shown after the magnitude of physical quantity according to representated by being actually needed loop current value being converted to it, The detection object that user finally wants to see can be directly displayed out, greatly meets the detection demand of user, it is practical.

2nd, the utility model need not be that it is additionally provided power supply at work, and it relies on from the electric current loop to be measured A part is extracted in current energy possessed by road itself, the electric energy for driving whole circuit operation can be provided, it is this The characteristics of power supply need not additionally be increased is it using with bringing facility in terms of maintenance.

3rd, the utility model is accessed in 4mA-20mA current loops to be measured in series connection in use, loop direct current caused by it Not over 1.7V, small power consumption is stable, reliable, will not produce any shadow to 4mA-20mA current loops to be measured for pressure drop Ring, can be connected in current loop and use for a long time.

Brief description of the drawings

Fig. 1 is composition frame chart of the present utility model.

Fig. 2 is the circuit theory diagrams of the utility model partial circuit.

Embodiment

The passive electric current loop measurement instrument of the utility model 4-20mA two-wire systems is used to be serially connected with current loop to be measured to use. As shown in figure 1, the utility model measuring instrument includes the two-wire system input terminal 11 for receiving the input current between 4mA-20mA；Two Line input terminal 11 is connected with gathering the current sampling circuit 12 of current loop current signal to be measured；Current sampling circuit 12 divides Two-way, all the way by the current signal collected to be converted into the current conversion circuit 13 of voltage signal with performing analog-to-digital conversion A/D convertor circuit 14 is connected, and then A/D convertor circuit 14 is connected by IIC universal serial bus with being used as the low-power scm 20 of master control Connect, another way and the energy for being transformed to supply voltage needed for power consuming circuit normal work from current loop collected current energy to be measured Amount Collection utilization circuit 15 connects；Collection of energy is current conversion circuit 13, A/D convertor circuit 14 and single-chip microcomputer using circuit 15 20 provide electric energy.

In the utility model, the electric current for the current loop to be measured consumption that current sampling circuit 12 is gathered, i.e. electric current disappears Consumption value utilizes the energy input of circuit 15 as collection of energy, and then the energy of input is entered using circuit 15 by collection of energy Row processing, generation are used for the power consuming circuit normal work institutes such as driving current translation circuit 13, A/D convertor circuit 14 and single-chip microcomputer 20 The supply voltage needed, to be implemented without the passive operation modes of additional power supply power supply, i.e., electricity is obtained from tested current loop The whole circuit can be driven to work.

Such as Fig. 1, the passive electric current loop measurement instrument of the utility model, which may also include, to be connected with single-chip microcomputer 20, as man-machine interaction Button inputting circuits 16.Button inputting circuits 16 are mainly used in loop current value and related physical to being set in single-chip microcomputer 20 Conversion rule between value is set etc..

Such as Fig. 1, the passive electric current loop measurement instrument of the utility model may also include the LCDs being connected with single-chip microcomputer 20 19 and for LCDs 19 provide backlight liquid crystal back light circuit 17.LCDs 19 can use segment code type liquid crystal display Screen etc..

In the utility model, single-chip microcomputer 20 is mainly used in carrying out necessary school to the current loop current signal of collection Accurate, nonlinear compensation processing, to calculate the loop current value that current loop flows through (full loop electric current is between 4mA-20mA) And this loop current value is scaled the related measurand value corresponding to it, and drive LCDs 19 finally to show Go out.

In addition, the utility model measuring instrument may also include the communicating circuit 18 being connected with single-chip microcomputer 20, communicating circuit 18 is used In setting relevant parameter with host computer communication.

Fig. 2 shows current sampling circuit 12, current conversion circuit 13, A/D convertor circuit 14 and collection of energy using electricity The circuit theory diagrams on road 15.

Such as Fig. 2, current sampling circuit 12 includes the current sample electricity being connected with the pin of two-wire system input terminal 11 (HX2) one Hinder R5, two-wire system input terminal HX2 another pin ground connection.Current conversion circuit 13 includes current detector U1 and (used INA169 chips) and voltage follower U2 (using TLC2252 chips).A/D convertor circuit 14 includes a/d converter U3 and (used ADS1110 chips).

Furthermore, it is understood that current detector U1 positive and negative input pin VIN+, VIN- are connected across current sampling resistor R5's Both ends, current detector U1 output pin OUT divide two-way, are connected all the way with voltage follower U2 positive input pin, another Road is connected with grounding resistance R1, and voltage follower U2 negative input pin after output pin short circuit with being commonly connected to a/d converter On U3 positive input pin VIN+, a/d converter U3 negative input pin VIN- ground connection, a/d converter U3 digital output interface While SCL, SDA pin are connected to pull-up resistor R6, R8 of communication respectively, it is connected with the respective pins of single-chip microcomputer 20.

In the utility model, single-chip microcomputer 20 is chosen as PIC16F946 chips.

Such as Fig. 2, collection of energy includes synchronous boost type converter U4 (using LTC3105 chips) using circuit 15.At this In utility model, collection of energy is that will collect what is come from current loop to be measured by diode using the main effect of circuit 15 Current energy is changed into voltage energy, and is exported after voltage energy is enlarged into the voltage that can drive power consuming circuit normal work.

Furthermore, it is understood that the synchronous boost type converter U4 tunnels of conversion input pin SW connection inductance L1 Hou Fen tetra-, first Road is connected with the output end of current sampling circuit 12, i.e., is connected with current sampling resistor R5, and the second tunnel is changed with synchronous boost type Device U4 input pin VIN connections, synchronous boost type converter U4 input pin VIN are connected with ground connection diode D2 simultaneously, Ground connection diode D2 negative pole is connected and plus earth with input pin VIN, and the 3rd tunnel is connected with ground capacity, i.e., with it is in parallel Three ground capacities C2, C3, C4 connection, the 4th tunnel are connected with two diodes D1, D3 of series connection, and diode D1 positive pole connects defeated Enter pin VIN and negative pole is connected with diode D3 positive pole, diode D3 negative pole ground connection；Synchronous boost type converter U4's is defeated Go out between pin VOUT and feedback pin FB the power supply circuit for being connected with and positive 3V supply voltages being simulated for producing, power supply circuit by Electric capacity C5, C6, resistance R10, R9 are formed, and are simulated positive 3V supply voltages and are used as current conversion circuit 13, A/D convertor circuit 14 With the supply voltage of single-chip microcomputer 20 these power consuming circuits.

In use, two pins of the two-wire system input terminal 11 of the utility model measuring instrument are serially connected with 4mA- to be measured In 20mA current loops, then, current sampling circuit 12, which gathers, flows through the current signal of current loop to be measured, and by current signal Voltage signal is converted to by current conversion circuit 13 and sends monolithic to after carrying out analog-to-digital conversion by A/D convertor circuit 14 Machine 20, calibrated by single-chip microcomputer 20, the processing such as nonlinear compensation, calculate loop current value, and by this loop current value The related measurand value corresponding to it is converted into, it is final to drive LCDs 19 to show.

During the utility model comes into operation, collection of energy utilizes circuit 15 from current loop collected current to be measured Energy, and this current energy is transformed to sufficiently large supply voltage, with supply current conversion circuit 13, A/D convertor circuit 14, The grade power consuming circuit of single-chip microcomputer 20 normal work uses.

The utility model has the advantages that：

The technical principle described above for being the utility model preferred embodiment and its being used, for those skilled in the art It is any based on technical solutions of the utility model basis in the case of without departing substantially from spirit and scope of the present utility model for member On equivalent transformation, it is simple replace etc. it is obvious change, belong within scope of protection of the utility model.

Claims

A kind of 1. passive electric current loop measurement instrument of 4-20mA two-wire systems, it is characterised in that：It includes receiving 4mA-20mA input electricity The two-wire system input terminal of stream；Two-wire system input terminal connects with gathering the current sampling circuit of current loop current signal to be measured Connect；Current sampling circuit divides two-way, passes through the current conversion circuit that the current signal collected is converted into voltage signal all the way It is connected with the A/D convertor circuit for performing analog-to-digital conversion, then A/D convertor circuit is connected by IIC universal serial bus with single-chip microcomputer, another Lu Yucong current loop collected current energy to be measured come be transformed to supply power consuming circuit normal work needed for voltage collection of energy Connected using circuit；Collection of energy using circuit is current conversion circuit, A/D convertor circuit and single-chip microcomputer provide electric energy.
2. the passive electric current loop measurement instrument of 4-20mA two-wire systems as claimed in claim 1, it is characterised in that：

The passive electric current loop measurement instrument of 4-20mA two-wire systems with the single-chip microcomputer also including being connected, pressing as man-machine interaction Key input circuit.
3. the passive electric current loop measurement instrument of 4-20mA two-wire systems as claimed in claim 1, it is characterised in that：

The passive electric current loop measurement instrument of 4-20mA two-wire systems also include the LCDs that is connected with the single-chip microcomputer and Liquid crystal back light circuit.
4. the passive electric current loop measurement instrument of 4-20mA two-wire systems as claimed any one in claims 1 to 3, it is characterised in that：

The current sampling circuit includes current sampling resistor；The current conversion circuit includes current detector and voltage follow Device；The A/D convertor circuit includes a/d converter.
5. the passive electric current loop measurement instrument of 4-20mA two-wire systems as claimed in claim 4, it is characterised in that：

The positive and negative input pin of the current detector is connected across the current sampling resistor both ends, the current detector Output pin divides two-way, is connected all the way with the positive input pin of the voltage follower, another way is connected with grounding resistance, described The negative input pin of voltage follower after output pin short circuit with being commonly connected on the positive input pin of the a/d converter, institute State a/d converter negative input pin ground connection, the a/d converter digital output interface connection pull-up resistor while with it is described The respective pins connection of single-chip microcomputer.
6. the passive electric current loop measurement instrument of 4-20mA two-wire systems as claimed any one in claims 1 to 3, it is characterised in that：

The single-chip microcomputer is PIC16F946 chips.
7. the passive electric current loop measurement instrument of 4-20mA two-wire systems as claimed any one in claims 1 to 3, it is characterised in that：

The collection of energy includes synchronous boost type converter using circuit.
8. the passive electric current loop measurement instrument of 4-20mA two-wire systems as claimed in claim 7, it is characterised in that：

The tunnels of conversion input pin connection inductance Hou Fen tetra- of the synchronous boost type converter, the first via and current sample electricity The output end connection on road, the second tunnel are connected with the input pin of the synchronous boost type converter, the synchronous boost type conversion The input pin of device is connected with ground connection diode simultaneously, and the 3rd tunnel is connected with ground capacity, the 4th tunnel and two two poles connected Pipe connects；It is connected to produce between the output pin and feedback pin of the synchronous boost type converter and simulates positive 3V power supplys electricity The power supply circuit of pressure, power supply circuit are made up of electric capacity, resistance.