CN1069153A - A kind of static small current communication loop - Google Patents

Abstract

The present invention relates to a kind of static small current communication loop.It is applicable to that microcomputer, instrument, instrument reach the communications service of setting up longer distance each other economically separately, is the strong communication network of a kind of antijamming capability.It is characterized in that adopting in the structure transmission loop and the receiving loop of photoelectricity isolation, the more important thing is and adopted static small current loop and send mode in parallel, thereby reach simple in structure, economical and practical, debug conveniently, even in remote multi-point communication, also can guarantee reliable, the very little communication of distortion.

Description

A kind of static small current communication loop

The present invention relates to a kind of static small current communication loop, it is applicable to that microcomputer, instrument, instrument reach the communications service of the longer distance of mutual foundation separately, is the strong communication network of a kind of antijamming capability.

In microcomputer, instrument, the widely used RS-232C serial interface devices of instrument, a kind of at present with voltage control mode transmission signal; Another kind of to transmit signal with the 20mA electric current loop.But they all have following deficiency: the former communication distance is short, generally can not surpass 100 meters, if will realize remote transmission, must additional expensive auxiliary communication apparatus, and cost is very high, and communication one to one on the same line road, can not multi-point communication; Moreover because this kind load mode must adopt common wire, thereby cause the common-mode noise interference easily.The latter, have or not the transmission signal because be with electric current, thereby cause the signal transmission voltage to change the spoke value and equal the loop service supply voltage, in signal transmits, because the circuit effects of distribution parameters, when transmitting range increases, the signal waveform duty cycle variations that transmits increases thereupon, cause wave distortion, error rate height, thereby transmitting range is also shorter.Simultaneously and when requiring to improve the loop service power supply when multi-point communication or lengthening communication distance, in communication process, because after too high supply voltage is added in the photoelectrical coupler two ends, fragile phototriode.

The object of the present invention is to provide a kind of atomic communication network of the distortion that can transmit at a distance easily that links to each other with serial interface devices.

The present invention finishes in the following way, and it is made up of identical in structure (1) and (2) two passages.Each passage is by signal sending link F ₁, F ₂F _n, signal receives link J ₁, J ₂J _nAnd three of signal transmit rings are partly formed.IN one to each passage brings in, and is the signal sendaisle, and other end OUT then is a receive path.Signal sending link F ₁, F ₂F _nPhototriode g ₁, g ₂G _nWith by resistance R.Adjustable resistance R _WThe static small current loop that is composed in series all is parallel to the direct current adjustable stabilized voltage supply E(-on the loop), A, the B point-to-point transmission of loop DC ammeter " A " (-) side, signal receives link J ₁, J ₂J _nLight-emitting diode D ₁, D ₂D _nAfter the series connection, one termination loop power E(+), other end T-Ring road ammeter " A " (+).By loop power E and J ₁, J ₂J _nThe signal of series connection receives the series loop and the g of link and loop current table " A " composition ₁, g ₂G _nThe shunt circuit of forming must be connected to the both sides of static small current loop AB respectively.Signal sending link F ₁, F ₂F _nEach concrete circuit all be identical.Signal sending link F ₁By triode T ₁, photoelectrical coupler d ₁, g ₁And resistance R ₁Constitute.T ₁Pipe is amplified to saturation conduction to the pulse signal that IN comes, and drives the light-emitting diode d of photoelectrical coupler ₁, make phototriode g1 obtain enough transfer currents and enter saturation conduction, because T ₁, g ₁Pipe all is operated on off state, guarantees the distortionless transmission conversion of input pulse.Photoelectrical coupler d ₁, g ₁Also play the buffer action of signal input end and loop end, effectively prevented mutual interference, finish an electrical-optical-electricity conversion signal transmission effect.Signal receives link J ₁, J ₂J _nConcrete circuit all identical.Signal receives link J ₂By photoelectrical coupler D ₂G ₂Three aurora T ₂And R ₂, R ₃, R _W1Form R wherein ₂Be 0.5～1 kilo-ohm, R ₃Be 2.4～3,3 kilo-ohms, R _WIt is 1～2 kilo-ohm.The light-emitting diode D of photoelectrical coupler ₂The signal current conversion that will flow through becomes the light signal, phototriode G ₂Again with light-emitting diode D ₂The light signal amplify and to convert current signal to and finish electrical-optical-electricity conversion, driving triode T ₂, R _W1, R ₃Be G ₂The load resistance of pipe also is that the quiescent point of T2 pipe is adjusted resistance, regulates R _W1Can change T ₂The saturation depth of pipe makes output OU _TObtain good output waveform.R ₂Be T ₂Supplying resistance, also be T ₂Load resistance.Photoelectrical coupler receives in the link at signal and has also played the electrical isolation effect of signal output end and loop end, thereby has strengthened the anti-interference of loop.The signal transmit ring is by power supply E, current surveillance table " A ", static small current loop resistance R, adjustable resistance R _WAnd signal sending link F ₁, F ₂F _nIn phototriode g ₁, g ₂G _nReceive link J with signal ₁, J ₂J _nIn light-emitting diode D ₁, D ₂D _nConstitute.Loop service power supply E is adjustable D.C. regulated power supply independently.Signal input and output loop is that electrical-optical-electric twice coupling by photoelectrical coupler finished, it is a kind of desirable isolation method, no matter be to the signal sending link, still signal is received link and can both thoroughly prevent the common-mode noise of invading in the transmission line, thereby avoided in a kind of " transmitting signal " of prior art, owing to be total to the shortcoming of the caused common-mode noise of signal ground wire with voltage control.This loop is owing to set up R _W, R series connection the static small current loop, be connected in parallel on A, the B point-to-point transmission of loop, when passage does not have signal and transmits, a static small current is arranged by E(+)-D ₁-D ₂-D _n-ammeter " A "-R-R _W-E(-) path flows, this be another kind in prior art " transmit signal " with the 20mA electric current loop do not have.When passage does not have the signal transmission, can contrast careful regulation loop power supply E of loop current Table A and static small current loop adjustable resistance R _W, make quiescent current at appropriate value.According to the discreteness of communication distance, communication number of spots and communication point, with lead short circuit loop A, B 2 points, adjustment loop electric current E makes loop current be transferred to certain value, and this electric current is the communication electric current.In general, communication distance is far away, and the many and dispersion of communication point can be selected the communication electric current bigger than normal, and vice versa.In conjunction with actual communication need, adjustment loop power supply and static small current loop resistance R repeatedly _WUntil the communication success, reach optimum state, the main effect that static small current flows through loop is to overcome light-emitting diode D ₁, D ₂D _nWork dead band about 1 volt makes it close region and sets up the quiescent operation voltage U at loop A, B two ends _AB, this voltage is the operating voltage of sending link.This point also is not available prior art a kind of " transmitting signal with the 20mA electric current loop ".In sending link when work,, phototriode is in the conducting of 2 of A, B and end, and is equivalent to and switches on and off A, B 2 points, and it is U that the loop voltage when making communication changes amplitude _ABThereby the pulse amplitude of variation has been improved the communication waveform when having controlled signal transmit ring transmission signal effectively.This point also is not accomplish a kind of " transmitting signal with the 20mA electric current loop " of prior art.Quiescent operation voltage U by static small current foundation _AB, mainly being subjected to the control of loop service power supply E, it should not transfer too highly, heightens U _ABThe loop service supply voltage that certainly will raise if power supply and quiescent operation overtension under long line effects of distribution parameters, when sending link ends, have too much charging current by transmission line and flow through loop, makes the time lengthening of electric current.Otherwise when voltage was low, the charging current of transmission line finished at once, makes the waveform duty cycle variations that is transmitted little, and the communication error rate is low.The passage course of work is to receive link F when signal ₁When input IN is low level, T ₁Pipe is owing to obtain by 5V through R ₁, d ₁, T ₁Emitter, T ₁Base stage flows to the low level base current of input IN and conducting, driven for emitting lights diode d ₁Light-emitting diode d is flow through in also conducting, electric current ₁Convert the light signal to, corresponding phototriode g ₁To d ₁The light signal that sends amplifies conversion makes its conducting, and it is similar to short circuit loop A, B 2 points.Loop quiescent operation voltage U _AB, because g ₁Manage conducting and become g ₁0.1～0.2 volt of the conduction pipe pressure drop of pipe, loop current is by the R that flows through _W, R static small current increase to the g that almost all flows through ₁The communication electric current of pipe.This electric current flows through the light-emitting diode D on the signal reception link in the loop ₁～D _nConvert the light signal to.Signal receives link J ₂Phototriode G ₂To D ₂The light signal that sends amplifies and converts electric current to and flow through G ₂Pipe makes its conducting, by the 5V R that flows through _W1Electric current all from the G of conducting ₂Pipe flows away, thereby makes T ₂Pipe base stage no current flows through T ₂Pipe ends owing to losing base current, makes the output OUT output high level opposite with IN.When signal receives link F ₁When input IN is high level, by 5V through R ₁, d ₁, T ₁Emitter flows to T ₁The electric current of base stage is owing to the rising of base potential stops to flow T ₁Pipe is owing to lose base current and entered by former conducting and end d ₁Pipe also ends d thereupon ₁Pipe stops luminous owing to no current flows through, corresponding phototriode g ₁Because unglazed signal is convertible, thereby enters cut-off state by former conducting, loop current is by the g that flows through ₁The communication electric current of pipe is reduced to the R that flows through _W, R static small current, simultaneously loop A, B end recovers the quiescent operation voltage U _ABBecause it is quiescent current is very little, not enough so that online light-emitting diode D ₁, D ₂D _nEnter luminous operating state, signal receives link J ₂Light-emitting diode D ₂, again because of the little deficiency of electric current so that it sends phototriode G ₂Can receive the signal light of conversion, G ₂Pipe is become by original conducting and ends, the 5V R that flows through _W1Electric current because G ₂Pipe ends, and through R ₃Flow into T ₂The base stage of pipe makes T ₂The pipe conducting causes the OUT output low level opposite with IN.Thereby the conversion of finishing a signal cycle transmits.In far away apart from 2 of loop A, the B in addition and communication networks that disperse, in order further to improve communication quality, also can be on the phototriode of sending link again and meet static small current loop resistance R, adjustable resistance R _W

Advantage of the present invention is simple in structure, economical and practical, debugging convenience, even in remote multi-point communication, also can guarantee communication quality height, strong interference immunity, the failure-free operation of energy long period, and, can avoid online communication apparatus to have a power failure or situation such as stoppage in transit and influence the normal communication of network because network communication adopts send mode in parallel.

The invention will be further described below in conjunction with accompanying drawing:

The present invention is made up of it (1) shown in Figure 1, (2).

Wherein: (1), (2) they are two passages of identical in structure, but because of IN end and different signal sendaisle and the signal receive paths of being divided in OUT end present position.Be the example explanation now with (1):

F ₁, F ₂F _n-identical in structure signal sending link.

J ₁, J ₂J _n-identical in structure signal receives link.

The adjustable DC power supply of E-loop.

A-50mA loop DC ammeter.

R _W, the static small current loop that is connected on 2 of loop A, B that is composed in series of R-.

With reference to Fig. 1, (1) passage F ₁Photoelectrical coupler light-emitting diode d ₁One side, supply voltage 5V is through R ₁, d ₁Meet T after the series connection ₁Emitter, base stage connect the OUT collector electrode and connect signal ground.Photoelectrical coupler phototriode one side g ₁, g ₂G _nEmitter and static small current loop one end be attempted by loop A point, the other end in its collector electrode and static small current loop is attempted by loop B point.The A point meets E(-), the B point connects ammeter " A " (-).J ₁, J ₂J _nPhotoelectrical coupler light-emitting diode one side, D ₁Negative electrode meets D ₂Anode, D ₂Negative electrode meets D _nAnode is after the series connection, by D ₁Anode meets E(+), D _nNegative electrode connects ammeter " A " (+).Photoelectrical coupler phototriode one side G ₂, T ₂Emitter also connects 5V ground, and its collector electrode is respectively through R _W1, R ₂And connection 5V, T ₂Base stage is through R ₃Meet G ₂Collector electrode, T ₂Collector electrode connects IN output.

(2) the passage connection is with (1) passage.

Claims (3)

1, a kind of static small current communication loop, it is made up of sending link, transmit ring and reception link, the invention is characterized in:

A, in transmit ring, static small current loop resistance R and adjustable resistance R _WAfter the series connection, be connected to A, the B point-to-point transmission of a loop power E (-) and loop current table " A " (-) side,

B, in receiving link, phototriode G ₂With triode T ₂Emitter be connected in parallel on 5V ground, phototriode G ₂Collector electrode through adjustable resistance R _W1Be connected on the 5V triode T ₂Collector electrode through resistance R ₂Also be connected on the 5V triode T ₂Base stage through resistance R ₃Meet phototriode G ₂Collector electrode, signal is then by triode T ₂Collector electrode output.

2, a kind of static small current communication loop according to claim 1.It is characterized in that receiving the adjustable resistance R in the link _W1Value is 1～2 kilo-ohm, resistance R ₂Value is 0.5～1 kilo-ohm, resistance R ₃Value is 2.4～3.3 kilo-ohms.

3, a kind of static small current communication loop according to claim 1, it is characterized in that in transmit ring, in and the communication networks that disperse far away apart from 2 of loop A, B, also can be on the phototriode of sending link, again and meet static small current loop resistance R and adjustable resistance R _W

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