CN207281529U - A kind of enabled control circuit of RS485 communications - Google Patents
A kind of enabled control circuit of RS485 communications Download PDFInfo
- Publication number
- CN207281529U CN207281529U CN201721278626.4U CN201721278626U CN207281529U CN 207281529 U CN207281529 U CN 207281529U CN 201721278626 U CN201721278626 U CN 201721278626U CN 207281529 U CN207281529 U CN 207281529U
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- Prior art keywords
- communication interface
- interface chips
- enabled control
- signal
- level signal
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Abstract
The utility model provides a kind of enabled control circuit of RS485 communications, including RS485 communication interface chips, power monitoring chip, RS485 communication interface chips and the power monitoring chip serial connection；The Enable Pin of the RS485 communication interface chips is used to control the enabled control signal of RS485 communication interface chips to input；The enabled control signal includes low level signal and high level signal, and the power monitoring chip includes clear counter and reset signal end；The timing reset function that the utility model passes through power monitoring chip, when the enabled control signal of RS485 communication interface chip Enable Pins is continuously high level signal in one cycle and is more than threshold time, reset signal end resets the high level signal for being more than threshold time duration, so that the problem of enabled control signal for solving RS485 communication interface chips is high level signal always, i.e., data are in transmission state and cause whole bus communication to be paralysed.
Description
Technical field
It the utility model is related to field of communication technology, the enabled control circuit of more particularly to a kind of RS485.
Background technology
In current RS485 circuits, the enabled foot of RS485 interface chips is directly controlled by MCU, to realize data
Send and receive.When the GPIO feet of control chip are high level, RS485 interface chips are in data sending state；Work as MCU
GPIO feet when being low level, RS485 interface chips are in data receiving state.
Since multiple equipment can be connected at the same time in RS485 buses, to form communication network, but in the same time,
There can only be an equipment to be in data sending state in RS485 buses, other equipment is in data receiving state, if two
A or two or more equipment is in data sending state, and RS485 buses will appear from problem.Therefore, once crashing occurs in MCU
During failure, the GPIO feet of MCU are likely to be constantly in high level signal or low level signal, if high level signal, then
RS485 interface chips will always be in data sending state, so as to cause whole RS485 buses communication abnormality occur.
Utility model content
To solve the above problems, the utility model provides a kind of enabled control circuit of RS485 communications, its feature exists
In：Including RS485 communication interface chips, power monitoring chip, the RS485 communication interface chips and power monitoring chip are serial
Connection；The RS485 communication interface chips include input, output end and Enable Pin, and Enable Pin is used to control RS485 communications to connect
The enabled control signal input of mouth chip；The enabled control signal includes low level signal and high level signal, described
When the enabled control signal of the Enable Pin of RS485 communication interface chips is low level signal, at the RS485 communication interface chips
In data receiving state；It is described when the enabled control signal of the Enable Pin of the RS485 communication interface chips is high level signal
RS485 communication interface chips are in data sending state；The power monitoring chip includes clear counter and reset signal end；Institute
State clear counter and be used to calculate the duration for enabling that control signal is high level signal in a cycle, the reset signal end
Exceed the high level signal of threshold time duration in a cycle for resetting.
In such scheme, the power monitoring chip is the internal reset chip for carrying WatchDog Timer function
MAX706, the reset cycle at reset signal end is 1.6 seconds.
The beneficial effects of the utility model are compared with prior art：The utility model is guarded the gate by power monitoring chip
Dog timing reset function, when the enabled control signal of RS485 communication interface chip Enable Pins is continuously high electricity in one cycle
Ordinary mail number and when exceeding threshold time, the reset signal end of power monitoring chip resets this high level signal, so as to solve
The enabled control signal of RS485 communication interface chips is high level signal always, i.e., data are in transmission state and cause whole
The problem of bus communication is paralysed.
Brief description of the drawings
Fig. 1 is the circuit structure block diagram of the utility model.
Embodiment
With reference to the accompanying drawings and examples, specific embodiment of the present utility model is described in further detail.Below
Embodiment is used to illustrate the utility model, but is not intended to limit the scope of the present invention.
As shown in Figure 1, a kind of enabled control circuit of RS485 communications, including RS485 communication interface chips, Power Supply Monitoring
Chip, RS485 communication interface chips and the power monitoring chip serial connection；The RS485 communication interface chips include defeated
Enter end, output terminal and Enable Pin, Enable Pin is used to control the enabled control signal of RS485 communication interface chips to input；Described
Enabled control signal includes low level signal and high level signal, the enabled control of the Enable Pin of the RS485 communication interface chips
When signal processed is low level signal, the RS485 communication interface chips are in data receiving state；The RS485 communication interfaces
When the enabled control signal of the Enable Pin of chip is high level signal, the RS485 communication interface chips are in data sending shape
State；The power monitoring chip includes clear counter and reset signal end；The clear counter is used to calculate in a cycle to make
Energy control signal is the duration of high level signal, and the reset signal end, which is used to reset in a cycle, exceedes threshold time
The high level signal of duration.RS485 interface chips are used to send data to RS485 buses or receive the RS485 buses
Data, transmission data mode is high level, and reception data mode is low level.
By taking power supply chip is MAX706 as an example, the reset cycle at the reset signal end of the chip is 1.6 seconds, when RS485 connects
Mouth chip is used to send data to RS485 buses, is high level, when low transition is into high level, clear counter starts to count
When, when reaching 1.6 seconds, the reset signal end of the MAX706 chips resets the Enable Pin of RS485 signals of communication, makes its RS485
Interface chip is used to control always in 1.6 seconds to RS485 buses transmission data, so as to ensure that RS485 bus communications are normal.
Above example is only to illustrate the technological thought of the utility model, it is impossible to the protection model of the utility model is limited with this
Enclose, it is every according to the utility model proposes technological thought, any change is made on the basis of technical solution, each falls within this reality
With in novel protected scope.
Claims (2)
- A kind of 1. enabled control circuit of RS485 communications, it is characterised in that：Including RS485 communication interface chips, Power Supply Monitoring core Piece, RS485 communication interface chips and the power monitoring chip serial connection；The RS485 communication interface chips include input End, output terminal and Enable Pin, Enable Pin are used to control the enabled control signal of RS485 communication interface chips to input；The enabled control signal includes low level signal and high level signal,When the enabled control signal of the Enable Pin of the RS485 communication interface chips is low level signal, the RS485 communications connect Mouth chip is in data receiving state；When the enabled control signal of the Enable Pin of the RS485 communication interface chips is high level signal, the RS485 communications connect Mouth chip is in data sending state；The power monitoring chip includes clear counter and reset signal end；The clear counter is used to calculate the duration for enabling that control signal is high level signal in a cycle, the reset Signal end is used to reset the high level signal for exceeding threshold time duration in a cycle.
- 2. the enabled control circuit of RS485 communications as claimed in claim 1, it is characterised in that：The power monitoring chip is Inside carries the reset chip MAX706 of WatchDog Timer function, and the reset cycle at reset signal end is 1.6 seconds.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721278626.4U CN207281529U (en) | 2017-09-30 | 2017-09-30 | A kind of enabled control circuit of RS485 communications |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721278626.4U CN207281529U (en) | 2017-09-30 | 2017-09-30 | A kind of enabled control circuit of RS485 communications |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN207281529U true CN207281529U (en) | 2018-04-27 |
Family
ID=61988653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201721278626.4U Expired - Fee Related CN207281529U (en) | 2017-09-30 | 2017-09-30 | A kind of enabled control circuit of RS485 communications |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN207281529U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110901707A (en) * | 2019-10-23 | 2020-03-24 | 北京全路通信信号研究设计院集团有限公司 | Remote monitoring device and method for automatic train protection system |
-
2017
- 2017-09-30 CN CN201721278626.4U patent/CN207281529U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110901707A (en) * | 2019-10-23 | 2020-03-24 | 北京全路通信信号研究设计院集团有限公司 | Remote monitoring device and method for automatic train protection system |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20180427 Termination date: 20200930 |