CN2790056Y

CN2790056Y - Photoelectric isolation active constant current long-distance digital signal transmission converter

Info

Publication number: CN2790056Y
Application number: CN 200520017872
Authority: CN
Inventors: 吴厚政
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-05-16
Filing date: 2005-05-16
Publication date: 2006-06-21
Anticipated expiration: 2015-05-16

Abstract

The utility model belongs to the technical field of digital signal transmission devices, which discloses an active constant current long-distance digital signal transmission converter of photoelectric isolation. The utility model is characterized in that the utility model comprises a photoelectric coupled circuit which receives TTL input digital signals, wherein the output end of the photoelectric coupled circuit is connected with the input end of a circuit, wherein the on-off value of the circuit is converted to active constant current digital signals, and the output end of the circuit is connected with the input end of the photoelectric coupled circuit which outputs digital signals. Since a power amplification circuit is used by the utility model, coupled output signals of a photoelectric coupler are directly converted to active constant current loop signals to be transmitted. The driving capacity of the signals is effectively improved, the quality of communicating signals is improved, and the utility model has the characteristics of long transmission distance, stable and reliable performance, etc. through experimental verification. The transmission for a longer distance can be realized through serially connecting the utility model on a position distanced for not more than 7000 meters, and the utility model is a preferred converter of long-distance digital signal transmission.

Description

Photoelectricity is isolated active constant current remote digital signal transmission converter

Technical field the utility model belongs to the digital data transmission equipment technical field, relates to a kind of photoelectricity and isolates active constant current remote digital signal transmission converter or repeater.

Background technology is along with the fast development of computer technology, interface circuit and similar parts thereof as computer serial communication are a lot, the standard serial communication interface has RS232, RS422, RS485,20mA electric current loop etc., however, but its transmission range is more limited, wherein the communication distance of transmission range RS485 farthest is 1200M, realize remote transfer of data, must on the position that is no more than 1200M at interval the repeater with same transfer function be installed.Though reached the purpose of digital signal long-distance transmissions like this, transmission means in the past exists such as failure rate height, unsatisfactory shortcoming such as the distortion of signal transmitted waveform is big, the error rate is high and communication baud rate is low.Although this has caused the concern of the parties concerned, up to the present also still find no successfully the report that solves, have only helplessly the traditional approach of continuing to use year after year to carry out long-distance transmissions.

Utility model content the purpose of this utility model provides transmission range 7000M under a kind of simple in structure, situation that transmission range in baud rate is 1200bps, it is stable and reliable for performance, obviously improve signal driving force, strengthen the broadband, reduce the error rate, and then the photoelectricity that improves signal transmission quality is isolated active constant current remote digital signal transmission converter.

The technical scheme of the utility model technical solution problem comprises: the output that receives the photoelectricity coupling circuit of TTL supplied with digital signal links to each other with the input that switching value is transformed into active constant current digital signal circuit, and the output of this circuit links to each other with the input of digital signal output photoelectricity coupling circuit.

Described switching value is transformed into the triode T in the active constant current digital signal circuit ₁, T ₂, base stage link to each other back and photoelectrical coupler U ₁4 pin and resistance R ₂An end link to each other T ₁With T ₂Emitter link to each other T ₂Collector electrode and resistance R ₂The other end link to each other, and pass through resistance R ₃An end and the resistance R of reciever ₅An end link to each other resistance R ₃The other end be connected on T ₁With T ₂Emitter between, T ₁Collector electrode and photoelectrical coupler U ₁5 pin and power supply V _Cc3Positive pole link to each other power supply V _Cc3Negative pole and photoelectrical coupler U ₂2 pin link to each other.

The utility model compared with prior art owing to utilize power amplification circuit, is directly changed into active continuous current ring signal to the coupling output signal of photoelectrical coupler and transmits, and has improved the driving force of signal effectively, has improved the signal of communication quality.And the experiment proved that this technology has long transmission distance, characteristics such as stable and reliable for performance.If want to transmit farther distance, can on the position that is no more than 7000M at interval, realize by this transducer of series connection.

Description of drawings Fig. 1 is circuit theory diagrams of the present utility model;

Fig. 2 is a circuit structure block diagram of the present utility model.

Embodiment with reference to the accompanying drawings, digital signal photoelectricity coupling circuit is to be the TTL logic level transition current output signal, realizes electrical isolation by photoelectrical coupler.Its input signal is sent into triode T ₃Base stage, T ₃Grounded collector, emitter links to each other with 2 pin of photoelectrical coupler, 1 pin of photoelectrical coupler is by current-limiting resistance R ₁With V _Cc1Link to each other, its output is used for the driving switch quantitative change and changes active constant current digital signal circuit into, the triode T in this circuit ₁, T ₂Base stage be plugged on photoelectrical coupler U after linking to each other ₁4 pin and resistance R ₂An end between, T ₁With T ₂Emitter link to each other T ₂Collector electrode and resistance R ₂And resistance R ₃An end and through resistance R ₅With photoelectrical coupler U ₂1 pin link to each other resistance R ₃The other end be connected on T ₁With T ₂Emitter between, T ₁Collector electrode and photoelectrical coupler U ₁5 pin and power supply V _Cc3Positive pole link to each other power supply V _Cc3Negative pole and photoelectrical coupler U ₂2 pin link to each other its photoelectrical coupler U ₂4 pin ground connection, 5 pin are by upper resistance R ₄With power supply V _Cc2Positive pole link to each other, 5 pin link to each other with Other Instruments, instrument serial communication interface TTL signal as the signal output lead end of TTL simultaneously.

The utility model is suitable for a port harbour flow circuit measuring parameter and detects, realize instrument, instrument remote transmission in the transmission of the distant signal between the control room and the various detecting instruments of plant area of petroleum chemical enterprise to the detected parameters between the Control Room, during use when input low level, triode T ₃Conducting, photoelectrical coupler U ₁Admittance makes conducting between pin 4 and the pin 5, and constant-current circuit has constant current output, receiving terminal photoelectrical coupler U ₂Admittance, output pin 5 output low levels; When the transmitting terminal input high level, triode T ₃End photoelectrical coupler U ₁End, this moment, constant-current circuit ended, no current output, and the output photoelectrical coupler also ends, output pin 5 output high level.

Claims

1, a kind of photoelectricity is isolated active constant current remote digital signal transmission converter, it is characterized in that it comprises: the output that receives the photoelectricity coupling circuit of TTL supplied with digital signal links to each other with the input that switching value is transformed into active constant current digital signal circuit, and the output of this circuit links to each other with the input of digital signal output photoelectricity coupling circuit.

2, photoelectricity according to claim 1 is isolated active constant current remote digital signal transmission converter, it is characterized in that described switching value is transformed into the triode T in the active constant current digital signal circuit ₁, T ₂, base stage link to each other back and photoelectrical coupler U ₁4 pin and resistance R ₂An end link to each other T ₁With T ₂Emitter link to each other T ₂Collector electrode and resistance R ₂The other end link to each other, and pass through resistance R ₃An end and the resistance R of reciever ₅An end link to each other resistance R ₃The other end be connected on T ₁With T ₂Emitter between, T ₁Collector electrode and photoelectrical coupler U ₁5 pin and power supply V _Cc3Positive pole link to each other power supply V _Cc3Negative pole and photoelectrical coupler U ₂2 pin link to each other.