CN201708517U - RS-485 communication interface protective circuit - Google Patents
RS-485 communication interface protective circuit Download PDFInfo
- Publication number
- CN201708517U CN201708517U CN2010201401247U CN201020140124U CN201708517U CN 201708517 U CN201708517 U CN 201708517U CN 2010201401247 U CN2010201401247 U CN 2010201401247U CN 201020140124 U CN201020140124 U CN 201020140124U CN 201708517 U CN201708517 U CN 201708517U
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- communication interface
- thermistor
- diode
- protective circuit
- thermistors
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- 238000004891 communication Methods 0.000 title claims abstract description 26
- 230000001681 protective effect Effects 0.000 title claims abstract description 12
- 239000000919 ceramic Substances 0.000 claims description 9
- 230000007704 transition Effects 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 11
- 230000015556 catabolic process Effects 0.000 description 3
- 239000011195 cermet Substances 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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Abstract
The utility model relates to an RS-485 communication interface protective circuit. Inlets of A and B ports of an RS-485 communication interface are respectively connected in series with one thermistor. Then the two thermistors are connected in parallel with the same gas discharge tube. The rear ends of the two thermistors are respectively connected in parallel with one diode. The diodes are earthed. When a 220V/380V power supply is switched in at the inlets of the A and B ports, currents much more than 100mA pass through between the PTC-36 omega thermistors and the P6KE6.8A diodes, so that the thermistors can move to be in an off state and the inlet end of the 485 interface is in an on state. No current enters a 485 circuit so as not to generate a burning accident caused by overvoltage and overcurrent. The utility model greatly improves safety and reliability of the product and avoids equipment loss and economic loss caused by wiring error.
Description
Technical field
The utility model relates to a kind of RS-485 communication interface protective circuit, relates in particular to the protective circuit of the anti-wrong 220V/380V power supply of a kind of RS-485 communication interface.
Background technology
In the modern communication technology, RS-485 communication is a kind of communication interface relatively more commonly used.The characteristics of RS-485 communication interface: the peak transfer rate 10Mbps of support, transmission range can reach 1200 meters farthest; Low power dissipation design, with the Transistor-Transistor Logic level compatibility; It is strong that anti-common mode is done ability; Adopt half-duplex operation, whenever can only have any to be in transmit status; Can be used for multi-point interconnection, constitute distributed system, save cable, be widely used in industrial control field.
Though the RS-485 communication interface is widely used, but in engineering construction, tend to because operating personnel's error is received the 220V/380V power supply on the RS-485 communication interface when wiring, cause the damage of 485 chips even associated circuit, cause unnecessary loss.Therefore, the anti-wrong 220V/380V processing to the RS-485 port is a very important problem.
The utility model content
The utility model corrects at above-mentioned problems, make circuit can system-wide protection, safe and reliable, simplicity of design, cost low.
Concrete technical scheme is:
A kind of RS-485 communication interface protective circuit; it is at the A of RS-485 communication interface ", " B " port porch last thermistor of respectively contacting; behind described two thermistors and connect same ceramic gas discharge tube; described two thermistor rear ends each and connect a diode, described diode ground connection.
The operating current of described thermistor is 100mA.
Described thermistor is a PTC-36 Ω thermistor.
Described diode suppresses diode for the TVS transition, and its operation voltage is 6.45V.
Described diode is the P6KE6.8A diode.
Because thermistor is a sensing element that is subjected to current affects, PTC-36 Ω operating current is 100mA, and ceramic gas discharge tube is to charge into suitable inert gas medium in discharging gap.Be equipped with highly active electronic emission material and the discharge mechanism of igniting, the gas discharge device of a kind of special cermet structure that forms by the high intermediate temperature sealing of noble metal scolder.When circuit had instantaneous overvoltage to scurry into, discharge tube was breakdown, and impedance descends rapidly, almost was short-circuit condition.P6KE6.8A diode action voltage is 6.45V; as " A ", when the 220V/380V power supply is inserted in " B " port porch; because the protection of ceramic gas discharge tube R2-75V or P6KE6.8A diode action; the electric current that flows through PTC-36 Ω thermistor will be much larger than 100mA; thereby cause the thermistor action; make power circuit be in off state, such 485 mouthfuls of high voltage sourcies that arrival end applied just can not be added on 485 communication lines, thereby have protected the RS485 communication port.
The utility model improves Product Safety greatly, and reliability is stopped wiring error and caused the damage of equipment to lose economically.
Description of drawings
Fig. 1 is the structural representation of the utility model embodiment.
Embodiment
Describe the utility model by the following examples, should be noted that, cited embodiment should not understand the restriction to utility model.
As shown in Figure 1: a kind of RS-485 communication interface of present embodiment protective circuit; its " A " in the RS-485 communication interface, " B " port porch add respectively serially add a last PTC-36 Ω thermistor and and a last ceramic gas discharge tube R2-75V; and the thermistor rear end each and on P6KE6.8A diode receive on the ground; because thermistor is a sensing element that is subjected to current affects; PTC-36 Ω operating current is 100mA, and ceramic gas discharge tube is to charge into suitable inert gas medium in discharging gap.Be equipped with highly active electronic emission material and the discharge mechanism of igniting, the gas discharge device of a kind of special cermet structure that forms by the high intermediate temperature sealing of noble metal scolder.When circuit had instantaneous overvoltage to scurry into, discharge tube was breakdown, and impedance descends rapidly, almost was short-circuit condition.P6KE6.8A diode action voltage is 6.45V; as " A ", when the 220V/380V power supply is inserted in " B " port porch; because the protection of ceramic gas discharge tube R2-75V or P6KE6.8A diode action; the electric current that flows through PTC-36 Ω thermistor will be much larger than 100mA; thereby cause the thermistor action; make power circuit be in off state, such 485 mouthfuls of high voltage sourcies that arrival end applied just can not be added on 485 communication lines, thereby have protected the RS485 communication port.
The operating characteristics of PTC-36 Ω thermistor: in 25 ± 2 ℃ of still airs of ambient temperature, during supply voltage 220VAC, by the 100mA electric current, thermistor entered high-impedance state in 60 seconds, just was in off-state between the two ends.
Ceramic gas discharge tube is to charge into suitable inert gas medium in discharging gap, is equipped with highly active electronic emission material and the discharge mechanism of igniting, the gas discharge device of a kind of special cermet structure that forms by the high intermediate temperature sealing of noble metal scolder.The puncture voltage of ceramic gas discharge tube R2-75V is 75V, and when circuit has when scurrying into greater than 75V voltage, discharge tube is breakdown, and impedance descends rapidly, almost is short-circuit condition.Discharge tube is released big electric current by line-to-ground or loop, also with voltage limit at electronegative potential, thereby protected circuit and equipment.After overvoltage surge disappears, promptly return to again 〉=high-impedance state of 1 begohm, guarantee the operate as normal of circuit.
P6KE6.8A is that the TVS transition suppresses diode, and operation voltage is 6.45V.If input voltage is greater than 6.45V, TVS is in the short circuit conducting state.
Present embodiment improves Product Safety greatly, and reliability is stopped wiring error and caused the damage of equipment to lose economically.
Obviously; foregoing is just in order to illustrate characteristics of the present utility model; and be not to restriction of the present utility model, the variation that the those of ordinary skill in relevant technologies field is made in the corresponding techniques field according to the utility model should belong to protection category of the present utility model.
Claims (5)
1. RS-485 communication interface protective circuit; it is characterized in that: the A of RS-485 communication interface, the B port porch last thermistor of respectively contacting; behind described two thermistors and connect same ceramic gas discharge tube; described two thermistor rear ends each and connect a diode, described diode ground connection.
2. a kind of RS-485 communication interface protective circuit according to claim 1, its feature also is: the operating current of described thermistor is 100mA.
3. a kind of RS-485 communication interface protective circuit according to claim 2, its feature also is: described thermistor is a PTC-36 Ω thermistor.
4. a kind of RS-485 communication interface protective circuit according to claim 1, its feature also is: described diode suppresses diode for the TVS transition, and its operation voltage is 6.45V.
5. a kind of RS-485 communication interface protective circuit according to claim 4, its feature also is: described diode is the P6KE6.8A diode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201401247U CN201708517U (en) | 2010-03-22 | 2010-03-22 | RS-485 communication interface protective circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201401247U CN201708517U (en) | 2010-03-22 | 2010-03-22 | RS-485 communication interface protective circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201708517U true CN201708517U (en) | 2011-01-12 |
Family
ID=43445668
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010201401247U Expired - Fee Related CN201708517U (en) | 2010-03-22 | 2010-03-22 | RS-485 communication interface protective circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201708517U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102420425A (en) * | 2011-12-26 | 2012-04-18 | 贵州航天天马机电科技有限公司 | Anti-surging protection device for computer controller |
| CN102723706A (en) * | 2012-05-30 | 2012-10-10 | 武汉烽火网络有限责任公司 | PoE port overvoltage comprehensive protection circuit and method for realizing same |
| CN104218560A (en) * | 2014-09-10 | 2014-12-17 | 国家电网公司 | RS485 communication protection circuit of electric energy meter |
| CN106786468A (en) * | 2017-02-20 | 2017-05-31 | 广州中大南沙科技创新产业园有限公司 | A kind of RS485 telecommunication equipment lightning protections and observation circuit |
-
2010
- 2010-03-22 CN CN2010201401247U patent/CN201708517U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102420425A (en) * | 2011-12-26 | 2012-04-18 | 贵州航天天马机电科技有限公司 | Anti-surging protection device for computer controller |
| CN102723706A (en) * | 2012-05-30 | 2012-10-10 | 武汉烽火网络有限责任公司 | PoE port overvoltage comprehensive protection circuit and method for realizing same |
| CN102723706B (en) * | 2012-05-30 | 2015-08-19 | 武汉烽火网络有限责任公司 | PoE port overvoltage integrated protection circuit and its implementation |
| CN104218560A (en) * | 2014-09-10 | 2014-12-17 | 国家电网公司 | RS485 communication protection circuit of electric energy meter |
| CN106786468A (en) * | 2017-02-20 | 2017-05-31 | 广州中大南沙科技创新产业园有限公司 | A kind of RS485 telecommunication equipment lightning protections and observation circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110112 Termination date: 20150322 |
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| EXPY | Termination of patent right or utility model |