CN204119260U - RS485 bus star expanding unit - Google Patents
RS485 bus star expanding unit Download PDFInfo
- Publication number
- CN204119260U CN204119260U CN201420523977.7U CN201420523977U CN204119260U CN 204119260 U CN204119260 U CN 204119260U CN 201420523977 U CN201420523977 U CN 201420523977U CN 204119260 U CN204119260 U CN 204119260U
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- interface circuit
- bus
- expanding unit
- interface
- star
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- 238000004891 communication Methods 0.000 abstract description 5
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000011514 reflex Effects 0.000 description 1
- 230000011664 signaling Effects 0.000 description 1
Abstract
The utility model discloses a kind of RS485 bus star expanding unit, comprise power supply, RS485 master interface circuit, RS485 is from interface circuit, described RS485 master interface circuit is connected from interface circuit with RS485, described RS485 is from interface circuit and RS485 equipment connection, described RS485 is at least two from interface circuit, described RS485 equipment is at least one and no more than 32, the utility model solves multiple RS485 equipment, the overload of RS485 bus is caused and cannot communication issue when being connected in parallel, and the structure can expanding RS485 bus is star or tree structure, and meet the requirement of RS485 specification.
Description
technical field:
The utility model relates to a kind of expanding unit, particularly relates to a kind of RS485 bus star expanding unit.
background technology:
RS485 communication has a wide range of applications in fields such as industry, electric power, and the common multifunction electric meter etc. as electric power system, is generally all equipped with RS485 communication interface.When carrying out automatic data logging, if the ammeter equipment connection of multiple RS485 interface together time, can realize easily wiring and communicate with ammeter.According to the requirement of RS485 specification, reduce signal reflex on the impact of RS485 bus, when connect multiple RS485 ammeter equipment time, need to connect into hand-in-hand daisy-chain fashion, can not star, tree structure.Simultaneously when on too much RS485 equipment connection to RS485 bus, because the overload in bus causes kilowatt meter recorder can not read data normal through RS485 bus from ammeter.
utility model content:
Technical problem to be solved in the utility model is: overcome the deficiencies in the prior art, there is provided a kind of structure simple, solve multiple RS485 equipment, cause the overload of RS485 bus and cannot the RS485 bus star expanding unit of communication issue when being connected in parallel.
The technical solution of the utility model is: a kind of RS485 bus star expanding unit, comprise power supply, RS485 master interface circuit, RS485 from interface circuit, described RS485 master interface circuit is connected from interface circuit with RS485, described RS485 is from interface circuit and RS485 equipment connection, described RS485 is at least two from interface circuit, and described RS485 equipment is at least one and no more than 32.
Described RS485 master interface circuit comprises RS485 change-over circuit and main RS485 interface, and described RS485 comprises RS485 change-over circuit and from RS485 interface from interface circuit.
Described RS485 change-over circuit comprises MAX485, resistance, thyristor.
Described RS485 master interface circuit is connected by SN7408J element from interface circuit with RS485.
The beneficial effects of the utility model are:
1, the utility model solves multiple RS485 equipment, causes the overload of RS485 bus and the problem that cannot communicate when being connected in parallel.
2, the utility model can expand the structure of RS485 bus is star or tree structure, and meets the requirement of RS485 specification, has ensured signaling rate.
accompanying drawing illustrates:
Fig. 1 is RS485 bus star expanding unit structured flowchart.
Fig. 2 is RS485 change-over circuit circuit diagram.
embodiment:
Embodiment: see Fig. 1 and Fig. 2.
RS485 bus star expanding unit: comprise power supply, RS485 master interface circuit, RS485 from interface circuit, RS485 master interface circuit is connected from interface circuit with RS485, RS485 is from interface circuit and RS485 equipment connection, RS485 is at least two from interface circuit, and RS485 equipment is at least one and no more than 32.
RS485 master interface circuit comprises RS485 change-over circuit and main RS485 interface, and RS485 comprises RS485 change-over circuit and from RS485 interface from interface circuit.
RS485 change-over circuit comprises MAX485, resistance, thyristor.
RS485 master interface circuit is connected by SN7408J element from interface circuit with RS485.
During use, RS485 equipment is divided into groups, often group is no more than 32, the RS485 interface of one group of RS485 equipment (being no more than 32) is connected to one of them from RS485 interface circuit, the like, main RS485 interface is as the communication interface of RS485 equipment, and the data that main RS485 interface receives are by sending from RS485 interface, and the data received from RS485 interface are sent by main RS485 interface.
Operation principle: when numeral 1 needs to be sent to A2, B2 from A1, B1, Txd1 is high level, Q1 conducting, and Dir1 is low level, therefore Rxd1(Txd2) be high level.Txd2 is high level, Q2 conducting, and Dir2 is low level, so now U2 is in accepting state.And the pull-up of R8 and the drop-down of R9, so A2>B2, so now the state of the RS485 bus of A2, B2 is numeral 1.When numeral 0 needs to be sent to A2, B2 from A1, B1, Txd1 is high level, Q1 conducting, and Dir1 is low level, therefore Rxd1(Txd2) be low level, Txd2 is low level, Q2 by, Dir2 is high level, and now U2 is in transmission state.Txd2 is low level, so now the RS485 bus state of A2, B2 is numeral 0, because circuit is symmetrical, when data send A1, B1 from A2, B2, performs similar process.
The above, it is only preferred embodiment of the present utility model, not any pro forma restriction is done to the utility model, every above embodiment is done according to technical spirit of the present utility model any simple modification, equivalent variations and modification, all still belong in the scope of technical solutions of the utility model.
Claims (4)
1. a RS485 bus star expanding unit, comprise power supply, RS485 master interface circuit, RS485 from interface circuit, it is characterized in that: described RS485 master interface circuit is connected from interface circuit with RS485, described RS485 is from interface circuit and RS485 equipment connection, described RS485 is at least two from interface circuit, and described RS485 equipment is at least one and no more than 32.
2. RS485 bus star expanding unit according to claim 1, is characterized in that: described RS485 master interface circuit comprises RS485 change-over circuit and main RS485 interface, and described RS485 comprises RS485 change-over circuit and from RS485 interface from interface circuit.
3. RS485 bus star expanding unit according to claim 2, is characterized in that: described RS485 change-over circuit comprises MAX485, resistance, thyristor.
4. RS485 bus star expanding unit according to claim 2, is characterized in that: described RS485 master interface circuit is connected by SN7408J element from interface circuit with RS485.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420523977.7U CN204119260U (en) | 2014-09-13 | 2014-09-13 | RS485 bus star expanding unit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420523977.7U CN204119260U (en) | 2014-09-13 | 2014-09-13 | RS485 bus star expanding unit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204119260U true CN204119260U (en) | 2015-01-21 |
Family
ID=52336535
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420523977.7U Active CN204119260U (en) | 2014-09-13 | 2014-09-13 | RS485 bus star expanding unit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN204119260U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11585835B2 (en) | 2021-01-15 | 2023-02-21 | Red Lion Controls, Inc. | System of determining the sequence and positioning of pluggable modules |
-
2014
- 2014-09-13 CN CN201420523977.7U patent/CN204119260U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11585835B2 (en) | 2021-01-15 | 2023-02-21 | Red Lion Controls, Inc. | System of determining the sequence and positioning of pluggable modules |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |