CN208782471U - A kind of RS-485 interface communication protection circuit based on industrial liquid crystal display - Google Patents

Abstract

The utility model discloses a kind of RS-485 interface communication protection circuit based on industrial liquid crystal display, belong to field of circuit technology, the RS-485_A line and RS-485_B line of the RS-485 has sealed in a self-recovery fuse respectively, RS-485_A line and RS-485_B line seal in a common mode inductance jointly, Transient Suppression Diode and a terminal coupling resistance have been respectively incorporated between RS-485_A line and RS-485_B line, it is provided with pull-up resistor on RS-485_A line, is provided with pull down resistor on RS-485_A line.The utility model RS-485 communication interface protection circuit, adding some basic resistance original parts using self-recovery fuse and TVS pipe can meet the requirements, and under the premise of guaranteeing to realize basic function, and can effectively reduce cost.

Description

A kind of RS-485 interface communication protection circuit based on industrial liquid crystal display

Technical field

The utility model belongs to field of circuit technology, and in particular to a kind of RS-485 interface based on industrial liquid crystal display Communicate protection circuit.

Background technique

RS-485 is as one of serial differential communication modes the most commonly used in current industry, using balance transmission, difference The mode of receiving, therefore there is the ability for inhibiting common mode interference, since it has communication over long distances, (communication distance is up to 1200M), higher transmission rate (transmission rate is up to 10Mbps), high signal-to-noise ratio, easy to control, cost is relatively low, Ke Yi The advantages that multinode and the transceiver being able to use wide in variety are realized in a piece individual bus, has obtained more and more use The approval and use at family.

But as frequency of use is also increasing the problem of increasing, encounter.Since RS-485 communication transmission line is usually sudden and violent It is exposed to open air, the electrostatic interference in daily life has become RS-485 communication bus in Practical Project frequently problem. In addition, the operating voltage of RS-485 transceiver is lower, only 5V, relatively low, the usually only -7V- of pressure resistance of component itself 12V.Therefore, power supply can damage RS-485 transceiver if there is the instantaneous pressure introduced extremely, cause to communication system Serious breaking-up, and electrostatic electromagnetic interference also seriously affects the data transmission quality of communication bus.

Summary of the invention

The purpose of this utility model is that: a kind of RS-485 interface communication protection electricity based on industrial liquid crystal display is provided Road solves RS-485 interface communication protection circuit in the prior art and realizes protection complicated, that shortage is to rear end single-chip microcontroller or guarantor The problem of protecting higher cost.

The technical solution adopted in the utility model is as follows:

A kind of RS-485 interface communication protection circuit based on industrial liquid crystal display, it is characterised in that: the RS-485 RS-485A line and RS-485B line sealed in a self-recovery fuse respectively, between RS-485_A line and RS-485_B line simultaneously Enter to have a Transient Suppression Diode, also seals in one respectively on transmitting-receiving pin EN, RXD, TXD that RS-485 is connected with single-chip microcontroller A resistance.

Further, it is also connected on the RS-485A line and is provided with a pull-up resistor, also connected on the RS-485B line It connects and is provided with a pull down resistor.

Further, terminal coupling resistance is incorporated between the RS-485A line and RS-485B line.

Further, the RS-485A line and RS-485B line have sealed in a common mode inductance jointly.

Further, the Transient Suppression Diode one is bipod TVS pipe, and one is three foot binary channels TVS pipes.

In conclusion by adopting the above-described technical solution, the beneficial effects of the utility model are:

1. in the utility model, the RS-485A line and RS-485B line of RS-485 sealed in respectively one regardless of it is polar from Restore fuse, the maximum rated operating voltage of self-recovery fuse is greater than circuit normal maximum operating voltage, keeps electric current Greater than circuit maximum operating currenbt, when short circuit or overload occur for route, the high current for flowing through self-recovery fuse is formed it into High-impedance state, operating current are reduced rapidly, to be limited circuit and be protected.After troubleshooting, self-recovery fuse Low resistive state is reverted to, so that the protection to circuit is completed, without artificial replacement.It is incorporated between RS-485A line and RS-485B line There is one regardless of polar bipod Transient Suppression Diode, breakdown voltage is slightly above the signal voltage transmitted on signal wire, is Back end communications chip provides protection.One has also been sealed in respectively on transmitting-receiving pin EN, RXD, TXD that RS-485 is connected with single-chip microcontroller The resistance of common optocoupler is substituted, can be played a protective role when RS-485 communication chip is damaged to rear end single-chip microcontroller.Meanwhile In such a way that resistance replaces common optocoupler, traditional scheme optocoupler had not only been realized to the defencive function of rear end single-chip microcontroller, but also effective It reduces costs.

2. in the utility model, it is connected with a pull-up resistor on the RS-485A line, on the RS-485B line It is connected with a pull down resistor.Pull-up resistor can provide electric current in bus driver scarce capacity, and pull down resistor then can It absorbs sink current and circuit anti-electromagnetic interference capability is improved by the setting of pull-up resistor and pull down resistor.

3. in the utility model, terminal coupling electricity is incorporated between the RS-485_A line and RS-485B line of the RS-485 Resistance so that signal does not reflect after reaching line end, and then protects original signal not by interference of reflected wave.

4. in the utility model, the RS-485_A line and RS-485B line of the RS-485 has sealed in a common mode electricity jointly Sense, greatly reduces the interference of common-mode signal, enhances the anti-interference ability of system.

5. in the utility model, being also incorporated with three feet between the RS-485A line and RS-485B line of the RS-485 Binary channels TVS pipe is able to suppress transient voltage and absorbs surge, forms duplicate protection with another TVS pipe.

Detailed description of the invention

In order to illustrate the technical solution of the embodiments of the present invention more clearly, below will be to needed in the embodiment attached Figure is briefly described, it should be understood that the following drawings illustrates only certain embodiments of the present invention, therefore is not construed as pair The restriction of range for those of ordinary skill in the art without creative efforts, can also be according to this A little attached drawings obtain other relevant attached drawings.

Fig. 1 is the utility model RS-485 interface communication protection circuit schematic diagram.

Specific embodiment

In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right The present invention is further elaborated.It should be appreciated that described herein, specific examples are only used to explain the present invention, not For limiting the present invention, i.e., described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is logical The component for the embodiment of the present invention being often described and illustrated herein in the accompanying drawings can be arranged and be designed with a variety of different configurations.

Therefore, the detailed description of the embodiment of the present invention provided in the accompanying drawings is not intended to limit below claimed The scope of the present invention, but be merely representative of selected embodiment of the invention.Based on the embodiment of the present invention, those skilled in the art Member's every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.

It should be noted that the relational terms of term " first " and " second " or the like be used merely to an entity or Operation is distinguished with another entity or operation, and without necessarily requiring or implying between these entities or operation, there are any This actual relationship or sequence.Moreover, the terms "include", "comprise" or its any other variant be intended to it is non-exclusive Property include so that include a series of elements process, method, article or equipment not only include those elements, but also Further include other elements that are not explicitly listed, or further include for this process, method, article or equipment it is intrinsic Element.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that including described There is also other identical elements in the process, method, article or equipment of element.

A kind of RS-485 interface communication protection circuit based on industrial liquid crystal display, connects for RS-485 in the prior art The problem of mouth communication protection circuit realizes complexity, lacks the protection to rear end single-chip microcontroller or protect higher cost, specifically: institute It states the RS-485A line of RS-485 and RS-485B line has sealed in a self-recovery fuse, RS-485A line and RS-485B line respectively A common mode inductance is sealed in jointly.It has been respectively incorporated into a bipod transient state between RS-485A line and RS-485B line and has inhibited two poles Pipe, a three foot Transient Suppression Diodes and a terminal coupling resistance are provided with pull-up resistor, RS- on RS-485_A line It is provided with pull down resistor on 485B line, has also sealed in one respectively on transmitting-receiving pin EN, RXD, TXD that RS-485 is connected with single-chip microcontroller A resistance.The self-recovery fuse can form high-impedance state when short circuit or overload occur for route, so that operating current is fast Speed reduces, to be limited circuit and be protected, after troubleshooting, self-recovery fuse reverts to low resistive state, thus The protection to circuit is completed, without artificial replacement.The breakdown voltage of the Transient Suppression Diode, which is slightly above on signal wire, to be transmitted Signal voltage, protection can be provided for back end communications chip.Transmitting-receiving pin EN, RXD, TXD that RS-485 is connected with single-chip microcontroller On also seal in the resistance for substituting common optocoupler respectively, both having realized biography in such a way that resistance replaces common optocoupler System scheme utilizes optocoupler to the defencive function of rear end single-chip microcontroller, and effectively reduces cost.It is arranged on the RS-485_A line Pull-up resistor electric current can be provided in bus driver scarce capacity, the pull down resistor being arranged on RS-485B line can then absorb Sink current improves its anti-electromagnetic interference capability by the setting of pull-up resistor and pull down resistor.The terminal coupling resistance energy Enough so that signal does not reflect after reaching line end, and then protect original signal not by interference of reflected wave.The common mode inductance energy Enough interference for greatly reducing common-mode signal, and then enhance the anti-interference ability of system.

Feature and performance of the invention are described in further detail with reference to embodiments.

Embodiment 1

A kind of RS-485 interface communication protection circuit based on industrial liquid crystal display that present pre-ferred embodiments provide, As shown in Figure 1, including Transient Suppression Diode, self-recovery fuse, common mode inductance and resistance, specifically: the RS-485 RS-485A line and RS-485B line sealed in a self-recovery fuse respectively, maximum rated operating voltage is being greater than circuit just The maximum voltage often to work, keeps electric current to be greater than the maximum operating currenbt that circuit works normally, and action current is less than route most Electric current, two self-recovery fuse FA=FB and not polarity, model SMD0805P010TF can be born greatly.It is protected in self- recoverage The rear end of dangerous silk, RS-485A line and RS-485B line seal in a common mode inductance jointly.Between RS-485A line and RS-485B line Also it has been respectively incorporated into a bipod Transient Suppression Diode, a three foot Transient Suppression Diodes and a terminal coupling electricity Resistance.Polarity, model SMBJ6.0CA, three pin Transient Suppression Diodes are not bilateral to the bipod Transient Suppression Diode Road TVS pipe, model NUP2105L, the breakdown voltage of the two are higher than the signal voltage transmitted on signal wire.The terminal coupling Resistance is patch thick-film resistor, and resistance value is 120 Ω.In addition, pull-up resistor is additionally provided on RS-485A line, in RS-485B line On be additionally provided with pull down resistor, pull-up resistor and pull down resistor are patch thick-film resistor, and resistance value is 4.7K Ω.RS-485 and list A patch thick-film resistor is also sealed on piece machine connected transmitting-receiving pin EN, RXD, TXD respectively, resistance value is 100 Ω, and substitution passes Common optocoupler in system scheme.In actual operation, self-recovery fuse can form height when short circuit or overload occur for route Resistance state, so that operating current is reduced rapidly, to be limited circuit and be protected.Described two Transient Suppression Diodes Breakdown voltage is slightly above the signal voltage transmitted on signal wire, can provide duplicate protection for back end communications chip.RS-485 with The resistance that one sealed in respectively on single-chip microcontroller connected transmitting-receiving pin EN, RXD, TXD substitutes common optocoupler both realizes tradition Scheme utilizes optocoupler to the defencive function of rear end single-chip microcontroller, and effectively reduces cost.It is arranged on the RS-485A line upper Pull-up resistor can provide electric current in bus driver scarce capacity, and the pull down resistor being arranged on RS-485B line can then absorb filling electricity Stream, by the setting of pull-up resistor and pull down resistor, improves the anti-electromagnetic interference capability of circuit.The terminal coupling resistance energy Enough so that signal does not reflect after reaching line end, and then protect original signal not by interference of reflected wave.The common mode inductance energy Enough interference for greatly reducing common-mode signal, and then enhance the anti-interference ability of system.The utility model RS-485 is logical Communication interface protects circuit, and required peripheral cell is considerably less, and design is simple, is added using self-recovery fuse and TVS pipe Basic resistive element can be met the requirements, and under the premise of guaranteeing to realize basic function, and can be effectively reduced into This.

The above is only the preferred embodiment of the utility model only, is not intended to limit the utility model, all at this Made any modifications, equivalent replacements, and improvements etc., should be included in the utility model within the spirit and principle of utility model Protection scope within.

Claims (5)

1. a kind of RS-485 interface communication protection circuit based on industrial liquid crystal display, it is characterised in that: the RS-485's RS-485_A line and RS-485_B line have sealed in a self-recovery fuse respectively, divide between RS-485_A line and RS-485_B line It is not incorporated to there are two Transient Suppression Diode, is also sealed in respectively on transmitting-receiving pin EN, RXD, TXD that RS-485 is connected with single-chip microcontroller There is a resistance.

2. a kind of RS-485 interface communication protection circuit based on industrial liquid crystal display according to claim 1, special Sign is: being also connected on the RS-485_A line and is provided with a pull-up resistor, is also connected with and is provided on the RS-485_B line One pull down resistor.

3. a kind of RS-485 interface communication protection circuit based on industrial liquid crystal display according to claim 1, special Sign is: also incorporating terminal coupling resistance between the RS-485_A line and RS-485_B line.

4. a kind of RS-485 interface communication protection circuit based on industrial liquid crystal display according to claim 1, special Sign is: the RS-485_A line and RS-485_B line have sealed in a common mode inductance jointly.

5. a kind of RS-485 interface communication protection circuit based on industrial liquid crystal display according to claim 1, special Sign is: the Transient Suppression Diode one is bipod TVS pipe, and one is three foot binary channels TVS pipes.