Utility model content
The purpose of this utility model is, by the remote analog acquisition device of a kind of communication formula, to solve the problem that above background technology part is mentioned.
For reaching this object, the utility model by the following technical solutions:
The remote analog acquisition device of a kind of communication formula, it comprises saw-toothed wave generator, high impedance signal Acquisition Circuit, real-time Comparison Circuit and spacing output circuit;
The output of described saw-toothed wave generator and the input electric connection of Comparison Circuit in real time, for adjusting as required sawtooth wave frequency, rising edge and trailing edge, obtain the sawtooth signal of required waveform, exports to real-time Comparison Circuit;
The output of described high impedance signal Acquisition Circuit and the input electric connection of Comparison Circuit in real time, for incoming analog signal, export to real-time Comparison Circuit;
The output of described real-time Comparison Circuit and the input of spacing output circuit are electrically connected, for sawtooth signal and analog signal are compared in real time, and output signal access spacing output circuit input; The pulse width modulating signal that spacing output circuit isolation output duty cycle and analog signal are proportional.
Especially, described saw-toothed wave generator comprises precision resistance R1, precision resistance R2, capacitor C 1, comparator U1A, capacitor C 2, resistance R 3, resistance R 4, resistance R 5 and triode Q1, wherein, one end ground connection after precision resistance R2 and capacitor C 1 are connected in parallel, one end of the other end and precision resistance R1, the inverting input of comparator U1A connects, the other end of precision resistance R1 connects external power supply, node after node contact resistance R3 after comparator U1A in-phase input end is connected with capacitor C 2 one end is connected with triode Q1 collector electrode, the other end ground connection of capacitor C 2, the other end of resistance R 3 connects external power supply, node connecting triode Q1 base stage after resistance R 4 one end are connected with resistance R 5 one end, resistance R 4 other ends connect comparator U1A output, node ground connection after resistance R 5 other ends are connected with triode Q1 emitter.
Especially, described saw-toothed wave generator also comprises capacitor C 3, and it is connected in resistance R 5 two ends in parallel.
Especially, described high impedance signal Acquisition Circuit comprises resistance R 6, resistance R 7, resistance R 8 and capacitor C 4; Wherein, one end ground connection after resistance R 8 is connected in parallel with capacitor C 4, the other end is connected with one end of resistance R 7, and the other end of resistance R 7 is connected with one end of resistance R 6, the other end incoming analog signal of resistance R 6.
Especially, described real-time Comparison Circuit comprises comparator U1B.
Especially, described spacing output circuit comprises optocoupler U2, resistance R 9 and capacitor C 5; Wherein, the node after resistance R 9 one end are connected with capacitor C 5 one end connects optocoupler U2 secondary, and the other end of resistance R 9 connects external power supply, the other end ground connection of capacitor C 5.
Especially, the remote analog acquisition device of described communication formula also comprises signaling conversion circuit; Described signaling conversion circuit is serially connected between real-time Comparison Circuit and spacing output circuit.
Especially, described signaling conversion circuit comprises resistance R 10, resistance R 11 and triode Q2; Wherein, the one end of node contact resistance R10 after triode Q2 base stage is connected with resistance R 11 one end, the other end of resistance R 10 connects the output of real-time Comparison Circuit, node ground connection after triode Q2 emitter is connected with resistance R 11 other ends, triode Q2 collector electrode connects spacing output circuit input.
The remote analog acquisition device of communication formula that the utility model provides has solved a difficult problem for the collection of small signal simulation amount remote isolation transmission, can be to a series of more accurate long-distance transmissions of analog quantity that can finally be expressed as voltage signal such as voltage, temperature, humidity, electric currents, and circuit structure is simple, cost is low.
Embodiment
Below in conjunction with drawings and Examples, the utility model is described in further detail.Be understandable that, specific embodiment described herein is only for explaining the utility model, but not to restriction of the present utility model.It also should be noted that, for convenience of description, in accompanying drawing, only show the part relevant to the utility model but not full content.
Please refer to shown in Fig. 1 and Fig. 2, in the present embodiment, the remote analog acquisition device of communication formula specifically comprises saw-toothed wave generator 101, high impedance signal Acquisition Circuit 102, real-time Comparison Circuit 103 and spacing output circuit 104.
The output of described saw-toothed wave generator 101 and the input electric connection of Comparison Circuit 103 in real time, for adjusting as required sawtooth wave frequency, rising edge and trailing edge, obtain the sawtooth signal of required waveform, exports to real-time Comparison Circuit 103.
In the present embodiment, described saw-toothed wave generator 101 comprises precision resistance R1, precision resistance R2, capacitor C 1, comparator U1A, capacitor C 2, resistance R 3, resistance R 4, resistance R 5, capacitor C 3 and triode Q1.Wherein, one end ground connection after precision resistance R2 and capacitor C 1 are connected in parallel, one end of the other end and precision resistance R1, the inverting input of comparator U1A connects, the other end of precision resistance R1 connects external power supply (5V), node after node contact resistance R3 after comparator U1A in-phase input end is connected with capacitor C 2 one end is connected with triode Q1 collector electrode, the other end ground connection of capacitor C 2, the other end of resistance R 3 connects external power supply, node connecting triode Q1 base stage after resistance R 4 one end are connected with resistance R 5 one end, resistance R 4 other ends connect comparator U1A output, node ground connection after resistance R 5 other ends are connected with triode Q1 emitter.In order to filter clutter, can be in a resistance R 5 two ends capacitor C 3 in parallel.
The divider resistance of precision resistance R1, precision resistance R2 composition reference power supply, by capacitor C 1 filtering, the negative terminal comparative voltage source of composition comparator U1A; Resistance R 3 and capacitor C 2 form capacitor charging circuit, form the rising edge waveform of sawtooth waveforms waveform.In charging process, in the time not reaching the reference voltage of comparator U1A inverting input, comparator U1A output output low level, the base stage of triode Q1 keeps electronegative potential by resistance R 5, the base voltage (Vbe) of triode Q1 does not obtain effective voltage, so triode Q1 does not amplify until saturation conduction, now, the waveform of triode Q1 collector electrode is the charge waveforms of capacitor C 2.In the time that comparator U1A in-phase input end voltage reaches the comparative voltage of benchmark, the output end voltage reversion of comparator U1A, become high level, this level is according to the reasonable dividing potential drop of resistance R 4 and resistance R 5, and capacitor C 3 is filtered clutter (capacitor C 3 can be removed depending on actual conditions), be added in triode Q1 base stage, make triode Q1 change into saturation conduction state from cut-off state, this process is the trailing edge of sawtooth waveforms waveform, this time can be by the reasonable dividing potential drop of adjusting resistance R4 and resistance R 5, the capacitance of capacitor C 3, and the parameter of triode Q1 is adjusted.Then, due to triode Q1 saturation conduction, the electric charge of storage in capacitor C 2 is discharged by triode Q1 immediately, after capacitor C 2 electric charges have discharged, comparator U1A in-phase input end becomes again electronegative potential, and the voltage of its in-phase input end is lower than the reference voltage of inverting input, thereby comparator U1A output output low level, triode Q1 reenters cut-off state, and capacitor C 2 and resistance R 3 are charged, next beginning that circulates.So go round and begin again, generate the sawtooth signal meeting the demands.
The output of described high impedance signal Acquisition Circuit 102 and the input electric connection of Comparison Circuit 103 in real time, for incoming analog signal, export to real-time Comparison Circuit 103.
High impedance signal Acquisition Circuit 102 adopts simple high impedance divider resistance to realize, and can reduce design cost, adopts little capacitor filtering simultaneously, reduces noise jamming.In the present embodiment, described high impedance signal Acquisition Circuit 102 comprises resistance R 6, resistance R 7, resistance R 8 and capacitor C 4.Wherein, one end ground connection after resistance R 8 is connected in parallel with capacitor C 4, the other end is connected with one end of resistance R 7, and the other end of resistance R 7 is connected with one end of resistance R 6, the other end incoming analog signal of resistance R 6.It should be noted that, it is simple that high impedance signal Acquisition Circuit 102 seems, but resistance R 6, resistance R 7, resistance R 8 must be selected suitable resistance, too little impedance easily causes the distortion of signal, too large impedance has easy introducing to disturb, to consider the input current that comparator U1B in real-time Comparison Circuit 103 needs simultaneously, be microampere (uA) rank or receive peace (nA) rank, so generally impedance can be considered at 100 kilo-ohms between 1 megaohm.For the scope of effective expression input signal, must select suitable dividing potential drop scope in addition, make the signal of the output duty cycle obtaining in wider scope, can not be always very little or always very large in gamut, affect sampling precision and sensitivity.
The input of the output of described real-time Comparison Circuit 103 and spacing output circuit 104 is electrically connected, for sawtooth signal and analog signal are compared in real time, output signal access spacing output circuit 104 inputs, spacing output circuit 104 is isolated pulse width modulation (PWM) signal of output duty cycle and the proportional fixed frequency of analog signal.
In the present embodiment, described real-time Comparison Circuit 103 comprises comparator U1B, use the comparator U1B of high impedance to compare in real time sawtooth signal and analog signal, output comparison waveform, if need to adjust the parameter of output waveform, can adjust the voltage ratio row of sawtooth signal and analog signal input and realize.Described spacing output circuit 104 comprises optocoupler U2, resistance R 9 and capacitor C 5.Wherein, node after resistance R 9 one end are connected with capacitor C 5 one end connects optocoupler U2 secondary, the other end of resistance R 9 connects external power supply, the other end ground connection of capacitor C 5, the former limit of optocoupler U2 connects comparator U1B output, node after comparator U1B in-phase input end contact resistance R3 is connected with triode Q1 collector electrode, the node after comparator U1B inverting input contact resistance R7 is connected with resistance R 8.Resistance R 9 is pull-up resistors, gives the certain operating current of output stage of optocoupler U2, and the filter capacitor that capacitor C 5 is high frequency, makes signal more clear.If need the reversion of signal, also can signal circuit for reversing be added in this level after, obtain reversion signal.
In addition, consider initial condition value to output waveform and the requirement of duty ratio, can between Comparison Circuit 103 and spacing output circuit 104, be connected in series a signaling conversion circuit 105 in real time.As shown in Figure 3, described signaling conversion circuit 105 comprises resistance R 10, resistance R 11 and triode Q2.Wherein, the one end of node contact resistance R10 after triode Q2 base stage is connected with resistance R 11 one end, the other end of resistance R 10 connects comparator U1B output, the node ground connection after triode Q2 emitter is connected with resistance R 11 other ends, and triode Q2 collector electrode connects the former limit of optocoupler U2.
The technical solution of the utility model has solved a difficult problem for the collection of small signal simulation amount remote isolation transmission, can be to a series of more accurate long-distance transmissions of analog quantity that can finally be expressed as voltage signal such as voltage, temperature, humidity, electric currents, as long as to the demarcation of surveyed analog quantity and corresponding duty specific energy real-time curve, among so actual use just than the analog quantity that is easier to obtain required collection, can simple table look-up, also can use simple linear function to calculate, and circuit structure is simple, cost is low.
Note, above are only preferred embodiment of the present utility model and institute's application technology principle.Skilled person in the art will appreciate that the utility model is not limited to specific embodiment described here, can carry out for a person skilled in the art various obvious variations, readjust and substitute and can not depart from protection range of the present utility model.Therefore, although the utility model is described in further detail by above embodiment, but the utility model is not limited only to above embodiment, in the situation that not departing from the utility model design, can also comprise more other equivalent embodiment, and scope of the present utility model is determined by appended claim scope.