CN220368470U - Error connection preventing circuit for RS485 port - Google Patents
Error connection preventing circuit for RS485 port Download PDFInfo
- Publication number
- CN220368470U CN220368470U CN202322045966.4U CN202322045966U CN220368470U CN 220368470 U CN220368470 U CN 220368470U CN 202322045966 U CN202322045966 U CN 202322045966U CN 220368470 U CN220368470 U CN 220368470U
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- misconnection
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- 230000002401 inhibitory effect Effects 0.000 claims abstract description 3
- 230000002265 prevention Effects 0.000 claims description 11
- 238000000034 method Methods 0.000 description 5
- 238000005303 weighing Methods 0.000 description 4
- 230000000703 anti-shock Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000006855 networking Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D10/00—Energy efficient computing, e.g. low power processors, power management or thermal management
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- Emergency Protection Circuit Devices (AREA)
Abstract
The utility model discloses an anti-misconnection circuit of an RS485 port, which is connected with an RS485 receiver, wherein the RS485 receiver is electrically connected with the RS485 port, the A end of the RS485 port is connected with the first end of a PTC resistor F2, the B end of the RS485 port is connected with the first end of a PTC resistor F1, the 1 st end of a common mode inductor L1 is connected with a resistor R2, the 2 nd end of the common mode inductor L1 is connected with the second end of the PTC resistor F1, the 3 rd end of the common mode inductor L1 is connected with a resistor R4, the common mode inductor L1 is used for inhibiting instant high voltage in the anti-misconnection circuit, the voltage is clamped at about 6V after a TVS diode V2 responds, the voltage does not exceed the upper limit of the resistance of the RS485 port, the RS485 receiver is prevented from being burnt, and the RS485 receiver is well protected.
Description
Technical Field
The utility model relates to the technical field of circuits, in particular to an anti-misconnection circuit for an RS485 port.
Background
The RS485 port of the weighing instrument is usually 3 ports, which are defined as an A end, a B end and a grounding end respectively. The power supply AC220V of the weighing instrument adopts 3 ports, which are defined as an L end, an N end and a grounding end respectively. For the weighing transmitter instruments, communication is performed through an RS485 networking modbus, so that several or more than ten instruments can be cascaded together through the RS 485.
In the process of on-site wiring, workers may mistakenly connect an AC220V power supply to the RS485 port, and all RS485 ports of networking instruments are burnt out only by powering on, so that certain loss is caused. Therefore, an anti-misconnection circuit of the RS485 port is required to be designed, and the instrument can still work normally after the AC220V power supply is connected with the RS485 for a plurality of hours.
Disclosure of Invention
The utility model aims to overcome the defects in the prior art and provides an RS485 port anti-misconnection circuit for an anti-burning RS485 port.
The aim of the utility model is realized by the following technical scheme:
the utility model provides a wrong connection prevention circuit of RS485 port, is connected with the RS485 receiver, the RS485 receiver electricity is connected with the RS485 port, prevent wrong connection circuit includes common mode inductance L1, resistance R2, resistance R4, TVS diode V2, PTC resistance F1, PTC resistance F2, the A end of RS485 port is connected with the first end of PTC resistance F2, the B end of RS485 port is connected with the first end of PTC resistance F1, common mode inductance L1 end is connected with resistance R2, common mode inductance L1 end 2 is connected with the second end of PTC resistance F1, common mode inductance L1 end 3 is connected with the second end of PTC resistance F2, common mode inductance L1 end 4 is connected with resistance R4, common mode inductance L1 is arranged in suppressing the high pressure in the wrong connection prevention circuit in the twinkling of an eye, when the L end and the N end of AC220V power insert respectively the A end and the B end of RS485 port, common mode inductance L1 end is connected with resistance R2, common mode inductance L1 end 3 is connected with PTC resistance F1's second end, common mode inductance L1 end 3 is connected with PTC resistance R2.
Further, the misconnection preventing circuit further includes a TVS diode V1 and a TVS diode V3, wherein a first end of the TVS diode V1 is connected to a second end of the PTC resistor F1, a first end of the TVS diode V3 is connected to a second end of the PTC resistor F2, and a second end of the TVS diode V1 is connected to a second end of the TVS diode V3.
Further, the misconnection preventing circuit further comprises a resistor R1, a first end of the resistor R1 is connected with a second end of the resistor R2, and a second end of the resistor R1 is grounded.
Further, the misconnection preventing circuit further comprises a resistor R3, and the resistor R3 is connected with the second end of the resistor R4.
Further, the second end of the resistor R2 is connected with the B end of the RS485 receiver, and the second end of the resistor R4 is connected with the A end of the RS485 receiver.
Further, the common mode inductor L1 is ACM4520-142.
Further, the model of the RS485 receiver is SN65LBC184.
Compared with the prior art, the utility model has the following advantages:
according to the utility model, before the TVS diode V2 does not respond, a certain anti-impact effect is achieved through the common-mode inductor L1, the resistor R2 and the resistor R4, after the TVS diode V2 responds, the voltage is clamped at about 6V and does not exceed the upper limit of the withstand voltage of the RS485 port, so that the RS485 receiver is prevented from being burnt, and the RS485 receiver is well protected.
Drawings
Fig. 1 is a circuit diagram of an RS485 port error-proofing circuit.
Detailed Description
It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.
The technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
It is noted that the terms "comprising," "including," and "having," and any variations thereof, in the description and claims of the utility model and in the foregoing figures, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus. In the claims, specification, and drawings of the present utility model, relational terms such as "first" and "second", and the like are used solely to distinguish one entity/operation/object from another entity/operation/object without necessarily requiring or implying any actual such relationship or order between such entities/operations/objects.
As shown in fig. 1, the embodiment provides an RS485 port misconnection prevention circuit, which is connected with an RS485 receiver U1, wherein the RS485 receiver U1 is electrically connected with an RS485 port J1, and the misconnection prevention circuit includes a common mode inductor L1, a resistor R2, a resistor R4, a TVS diode V2, a PTC resistor F1, and a PTC resistor F2, wherein the common mode inductor L1 is mainly resistant to common mode interference and has a certain suppression effect on instantaneous high voltage, the model of the common mode inductor L1 is ACM4520-142, and the model of the RS485 receiver U1 is SN65LBC184; the end A of the RS485 port J1 is connected with the first end of the PTC resistor F2, the end B of the RS485 port J1 is connected with the first end of the PTC resistor F1, the end 1 of the common mode inductor L1 is connected with the resistor R2, the end 2 of the common mode inductor L1 is connected with the second end of the PTC resistor F1, the end 3 of the common mode inductor L1 is connected with the second end of the PTC resistor F2, the end 4 of the common mode inductor L1 is connected with the resistor R4, and the common mode inductor L1 is used for inhibiting instant high voltage in an anti-misconnection circuit;
one example is: when the L end and the N end of the AC220V power supply are respectively connected with the A end and the B end of the RS485 port J1:
the common-mode inductor L1, the resistor R2 and the resistor R4 play a certain role in anti-shock before the TVS diode V2 does not respond, and the voltage is clamped at about 6V after the TVS diode V2 responds, and meanwhile, a large current flows through the TVS diode V2, the PTC resistor F1 and the PTC resistor F2. When large current flows through the PTC resistor F1 and the PTC resistor F2, the PTC resistor F1 and the PTC resistor F2 generate heat, meanwhile, the resistance values of the PTC resistor F1 and the PTC resistor F2 are increased, the PTC resistor F1 and the PTC resistor F2 are thermistors with voltage withstanding 250V and working current 60mA, when the flowing current exceeds 500mA, the PTC resistor F1 and the PTC resistor F2 are in a high resistance state, the PTC resistor F1 and the PTC resistor F2 are semiconductor resistors with temperature sensitivity, and when the temperature exceeds a certain temperature (Curie temperature), the resistance values of the PTC resistors are increased in a step-like manner along with the temperature rise; at this time, the current flowing through the TVS diode V2 is reduced to about 20mA, and the anti-misconnection circuit keeps the current flowing through the TVS diode V2 reduced to about 20mA as long as the AC220V power supply is not disconnected. Because the TVS diode V2 always clamps the voltage at 6V and the voltage resistance upper limit of the RS485 port J1 is not exceeded, the RS485 receiver U1 is prevented from being burnt, and the RS485 receiver U1 is well protected.
Another embodiment is: when the L end and the N end of the AC220V power supply are respectively connected with the A end and the grounding end of the RS485 port J1:
the common-mode inductor L1, the resistor R2 and the resistor R4 play a certain role in anti-shock before the TVS diode V2 does not respond, and the voltage is clamped at about 6V after the TVS diode V2 responds, and meanwhile, a large current flows through the TVS diode V2, the PTC resistor F1 and the PTC resistor F2. When large current flows through the PTC resistor F1 and the PTC resistor F2, the PTC resistor F1 and the PTC resistor F2 generate heat, and simultaneously the resistance values of the PTC resistor F1 and the PTC resistor F2 are increased; at this time, the current flowing through the TVS diode V2 is reduced to about 20mA, and the anti-misconnection circuit keeps the current flowing through the TVS diode V2 reduced to about 20mA as long as the AC220V power supply is not disconnected. Because the TVS diode V2 always clamps the voltage at 6V and the voltage resistance upper limit of the RS485 port J1 is not exceeded, the RS485 receiver U1 is prevented from being burnt, and the RS485 receiver U1 is well protected.
The principle is the same when the L end and the N end of the AC220V power supply are respectively connected with the B end and the grounding end of the RS485 port J1; through verification of the three error connection modes, after an AC220V power supply is inserted into an RS485 port J for 14 hours, the test RS485 interface still works normally, and the error connection prevention circuit for the RS485 port effectively avoids the problems that a field worker connects an error line and burns out the RS485 port J1, reduces loss for companies and clients, and prevents the RS485 port J1 of a weighing instrument from being burnt out.
In addition, the misconnection prevention circuit further comprises a TVS diode V1 and a TVS diode V3, wherein the first end of the TVS diode V1 is connected with the second end of the PTC resistor F1, the first end of the TVS diode V3 is connected with the second end of the PTC resistor F2, the second end of the TVS diode V1 is connected with the second end of the TVS diode V3, and the TVS diodes V1, V2 and V3 are TVS diodes of 6V, mainly playing a role of voltage clamping and having a high reaction speed.
The misconnection prevention circuit further comprises a resistor R1, wherein a first end of the resistor R1 is connected with a second end of the resistor R2, a second end of the resistor R1 is grounded, and the resistor R1 is a pull-down resistor and is used for absorbing current and resisting interference. The misconnection prevention circuit further comprises a resistor R3, and the resistor R3 is connected with the second end of the resistor R4. The second end of the resistor R2 is connected with the B end of the RS485 receiver U1, the second end of the resistor R4 is connected with the A end of the RS485 receiver U1, the resistor R2 is a pull-up resistor, the output level of the RS485 receiver U1 is improved, accordingly, the noise margin of an input signal of the RS485 receiver U1 is improved, the anti-interference capability is enhanced, the resistor R2 and the resistor R4 are 1/2W resistors, and the effect of limiting current is achieved to prevent an antistatic tube at the inner port of the RS485 receiver U1 from being broken down.
It should be noted that the above-mentioned embodiments are merely preferred examples of the present utility model and the technical principles applied, and any changes, modifications, substitutions, combinations and simplifications made by those skilled in the art without departing from the spirit and principles of the present utility model should be equivalent substitution manner within the scope of the present utility model.
Claims (7)
1. An anti-misconnection circuit of an RS485 port is connected with an RS485 receiver, and the RS485 receiver is electrically connected with the RS485 port, and is characterized in that: the anti-misconnection circuit comprises a common-mode inductor L1, a resistor R2, a resistor R4, a TVS diode V2, a PTC resistor F1 and a PTC resistor F2, wherein the A end of an RS485 port is connected with the first end of the PTC resistor F2, the B end of the RS485 port is connected with the first end of the PTC resistor F1, the 1 st end of the common-mode inductor L1 is connected with the resistor R2, the 2 nd end of the common-mode inductor L1 is connected with the second end of the PTC resistor F1, the 3 rd end of the common-mode inductor L1 is connected with the second end of the PTC resistor F2, the 4 th end of the common-mode inductor L1 is connected with the resistor R4, and the common-mode inductor L1 is used for inhibiting instant high voltage in the anti-misconnection circuit.
2. The RS485 port anti-misconnection circuit of claim 1, wherein: the misconnection prevention circuit further comprises a TVS diode V1 and a TVS diode V3, wherein a first end of the TVS diode V1 is connected with a second end of the PTC resistor F1, a first end of the TVS diode V3 is connected with a second end of the PTC resistor F2, and a second end of the TVS diode V1 is connected with a second end of the TVS diode V3.
3. The RS485 port anti-misconnection circuit of claim 1, wherein: the misconnection prevention circuit further comprises a resistor R1, wherein a first end of the resistor R1 is connected with a second end of the resistor R2, and a second end of the resistor R1 is grounded.
4. The RS485 port anti-misconnection circuit of claim 1, wherein: the misconnection prevention circuit further comprises a resistor R3, and the resistor R3 is connected with the second end of the resistor R4.
5. The RS485 port anti-misconnection circuit of claim 1, wherein: and the second end of the resistor R2 is connected with the end B of the RS485 receiver, and the second end of the resistor R4 is connected with the end A of the RS485 receiver.
6. The RS485 port anti-misconnection circuit of claim 1, wherein: the common mode inductance L1 is ACM4520-142.
7. The RS485 port anti-misconnection circuit of claim 1, wherein: the model of the RS485 receiver is SN65LBC184.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322045966.4U CN220368470U (en) | 2023-07-31 | 2023-07-31 | Error connection preventing circuit for RS485 port |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322045966.4U CN220368470U (en) | 2023-07-31 | 2023-07-31 | Error connection preventing circuit for RS485 port |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220368470U true CN220368470U (en) | 2024-01-19 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322045966.4U Active CN220368470U (en) | 2023-07-31 | 2023-07-31 | Error connection preventing circuit for RS485 port |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220368470U (en) |
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2023
- 2023-07-31 CN CN202322045966.4U patent/CN220368470U/en active Active
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