CN105357072A - Electric power meter with functions of realizing optoelectronic isolation and preventing RS485 communication bus occupation faults - Google Patents
Electric power meter with functions of realizing optoelectronic isolation and preventing RS485 communication bus occupation faults Download PDFInfo
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- CN105357072A CN105357072A CN201510782165.3A CN201510782165A CN105357072A CN 105357072 A CN105357072 A CN 105357072A CN 201510782165 A CN201510782165 A CN 201510782165A CN 105357072 A CN105357072 A CN 105357072A
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Abstract
The invention discloses an electric power meter with functions of realizing optoelectronic isolation and preventing RS485 communication bus occupation faults. The electric power meter comprises a main CPU module, an alternating-current voltage input module, a storage module, a communication isolation module, a communication protection module, an RS485 communication interface module, a power module and an indicator lamp. The communication isolation module is used for performing optoelectronic isolation on a communication signal of the main CPU module. The communication protection module is used for maintaining receiving and transmitting states of an RS485 communication interface. According to the electric power meter, a communication transmitting signal is adopted as a trigger signal of transmitter enable, so that the control of a CPU on a communication enable signal and a corresponding isolation chip in the prior art is removed; (1) the communication isolation cost can be reduced; and (2) due to the adoption of a communication protection circuit, the phenomenon of RS485 communication bus occupation caused by communication enable signal exception caused by a CPU fault, an optoelectronic isolation fault and other faults can be effectively prevented, the systematic fault risk can be lowered, and the system reliability can be improved.
Description
Technical field
The invention belongs to Automation of Electric Systems, relate to and possess Phototube Coupling and prevent RS485 communication bus from accounting for the electric instrument of dead fault function.
Background technology
RS485 communication extensive use in a variety of systems, it is communication media usually with Shielded Twisted Pair, adopts half duplex communication mode, can realize multimachine work communication bus; But, after there is an equipment fault be connected on RS485 communication bus in practical application, communication bus accounted for dead and cause the phenomenon that whole communication network is paralysed, in most cases owing to can not determine failed equipment, usually need to investigate the device on communication bus one by one, time-consumingly to take a lot of work.
Summary of the invention
Technical problem to be solved by this invention makes up above-mentioned defect, provides a kind of and possess Phototube Coupling simultaneously and prevent RS485 communication bus from accounting for the electric instrument of dead fault function.
Technical problem of the present invention is solved by the following technical programs.
This possess Phototube Coupling and prevent RS485 communication bus from accounting for the electric instrument of dead fault function, comprises host CPU module, AC current-voltage input module; memory module, communication isolation module, communication protection module; RS485 communication interface module, power module and indicator light.
Described host CPU module is used for carrying out sampling to the AC signal of input and calculates, and obtains the various electric power data of electric instrument, receives the communication packet of RS485 communication interface module simultaneously, and sent by RS485 communication interface module by response message.
Described AC current-voltage input module is used for changing AC current-voltage signal.
Described memory module is used for stores meter configuration information, as address, tuning parameter etc.
Described communication isolation module is used for carrying out Phototube Coupling to the communication signal of host CPU module, and the communication signal of host CPU module comprises communication and sends signal TXD and communication Received signal strength RXD.
Described communication protection module, for safeguarding the reiving/transmitting state of RS485 communication interface, prevents RS485 communication interface to be in transmission state for a long time and causes accounting for of RS485 communication bus dead.
Described RS485 communication interface module is for realizing the conversion of RS485 signal.
This feature automatically preventing RS485 communication bus from accounting for the electric instrument of dead fault is:
Described communication protection module sends signal trailing edge by the communication of host CPU module and triggers; automatically, will " send " signal enable and be set to 1; make RS485 communication interface module state auto-switching to transmission state, can output on RS485 communication bus so that the communication of host CPU module sends signal.
Described communication protection module is after the communication of host CPU module sends and stops, and time delay T millisecond automatically will " send " signal afterwards enable and be set to 0, thus RS485 communication interface module is switched to accepting state.
The trailing edge that described communication protection module sends signal by the communication of host CPU module triggers; and send time delay T millisecond when signal keeps certain level in communication just to automatically shut down, can effectively prevent the transmission enable signal caused as CPU exception or circuit abnormality be in the normal state 1 state.
Described communication protection module can utilize the communication of CPU module to send signal and automatically produce " sending enable " signal, need not the transmission of CPU module controls RS485 communication and accepting state, can reduce communication and isolate cost.
Host CPU module and external communication interface can be kept apart by described communication isolation module, external communication line is avoided to disturb the normal work of host CPU module, meanwhile, when multiple instrument shares a RS485 communication bus, make the isolated from power between each instrument, prevent potential safety hazard.
Technical problem of the present invention is solved by following further technical scheme:
Described communication protection module is made up of a monostable trigger-action circuit, and its output pulse width T can regulate.
Described communication protection module input control end is that the communication of the host CPU module of isolating through communication isolation module sends signal TXD, adopts trailing edge to trigger.
Described communication protection module output signal sends enable signal TEN for RS485, directly accesses RS485 interface chip and sends enable pin.
TEN is set to 1 by described communication protection module after receiving TXD signal trailing edge first; If again do not receive TXD signal trailing edge in T time, then TEN automatic resetting is 0; If again receive TXD signal trailing edge in T time, then making it export pulse, to be extended to TEN automatic resetting after this trailing edge T be 0.
The monostable trigger-action circuit of described communication protection module can adopt hardware mode to form, and hardware timer mode also can be adopted to form, and only needs the function that can complete [0019]-[0022].
Technical problem of the present invention is solved by following further technical scheme.
Described host CPU module is made up of MSP430 and peripheral circuit, the communication signal adopted is communication signal TXD, RXD of the Universal Asynchronous Receive/dispensing device (UniversualAsynchronousReceiver/Transmitter, initialism is UART) of MSP430 built-in chip type.
Described communication isolation module adopts photoelectric isolated chip 6N137, is isolated by TXD, RXD signal.
Described communication protection module adopts Schmidt trigger 74HC123, described communication isolation module adopts photoelectric isolated chip 6N137, and the communication after being isolated by TXD, RXD signal sends the trailing edge trigger pin of the Schmidt trigger 74HC123 of signal TXD incoming communication protected location; Adjustment Schmidt trigger 74HC123 outer meeting resistance electric capacity is adopted to regulate monostable trigger-action circuit output pulse width T; Its communication exported sends enable signal access RS485 communication interface module.
Described RS485 communication interface module is made up of RS485 level transferring chip 65LBC184 and peripheral overvoltage crowbar; It sends Enable Pin and is controlled by described communication protection module, and output terminals A, the B of communication interface module are received on external communication circuit by the overvoltage crowbar of communication interface module.
Described indicator light comprises plant running indicator light, RS485 communication indicator light.
The present invention's beneficial effect is compared with prior art:
The present invention adopts communication to send signal TXD as sending enable triggering signal; eliminate CPU communication control enable signal and corresponding isolating chip in prior art; communication isolation cost can be reduced on the one hand; on the other hand; owing to adopting communication protective circuit; the RS485 communication bus that the communication enable signal that can effectively prevent such as cpu fault, Phototube Coupling fault and other fault from causing is abnormal and cause accounts for dead phenomenon, reduces systematic failure risk, improves the reliability of system.
Accompanying drawing explanation
Fig. 1 is the compositional block diagram of the specific embodiment of the invention.
Fig. 2 is the schematic diagram of communication protection module in Fig. 1.
Fig. 3 is the schematic diagram of communication isolation module in Fig. 1.
Embodiment
Contrast accompanying drawing to be below described the specific embodiment of the present invention.
A kind of possessing Phototube Coupling and preventing RS485 communication bus from accounting for the electric instrument of dead fault function as shown in Figure 1; when accessing on RS485 communication bus; its communication protection module can effectively prevent RS485 communication bus extremely occupied because of plant failure; its photoelectric isolation module can avoid external communication line to disturb the normal work of host CPU module; simultaneously; when multiple instrument shares a RS485 communication bus, make the isolated from power between each instrument, prevent potential safety hazard.Its parts comprise:
Host CPU module comprises master chip MSP430 and peripheral circuit, adopts the communication signal of the Universal Asynchronous Receive/dispensing device (UART) of MSP430 built-in chip type.Host CPU module completes the function such as data acquisition calculating, storage, communication management of electric instrument.
Adopt the switch power module of pulse transformer, for whole instrument provides various power supply.
Communication isolation module adopts photoelectric isolating device the communication signal of host CPU and external communication interface to be isolated.
Communication protection module adopts Schmidt trigger 74HC123, and the communication after the isolation of communication isolation module sends the trailing edge trigger pin of the Schmidt trigger 74HC123 of signal incoming communication protected location; Adjustment Schmidt trigger 74HC123 outer meeting resistance electric capacity is adopted to regulate monostable trigger-action circuit output pulse width T; Its communication exported sends enable signal access RS485 communication interface module.
RS485 communication interface module is made up of RS485 level transferring chip 65LBC184 and peripheral overvoltage crowbar; It sends Enable Pin and is controlled by communication protection module, and output terminals A, the B of communication interface module are received on external communication circuit by the overvoltage crowbar of communication interface module.
Memory module is by Serial E
2pROM and FLASH is formed, and preserves instrument arrangement information, as address, tuning parameter etc.
Indicator light comprises plant running indicator light, RS485 communication indicator light.
AC current-voltage input module is made up of voltage transformer, current transformer, operational amplification circuit and filter circuit, for changing AC current-voltage signal.
The course of work of this embodiment is:
Under normality, the output TEN of communication protection module is in 0 state; this is determined by monostable trigger-action circuit characteristic; after communication protection module receives the trailing edge triggering of the communication transmission signal of host CPU after the isolation of communication isolation module; its output TEN becomes 1 state, and keeps a pulse width T.In this case, communication interface module is in transmission enabled state, and the transmission information of host CPU can be sent on RS485 communication bus through communication isolation module, communication interface module.
If communication protection module receives again a trailing edge triggering signal in T time, then the time that output TEN remains 1 is calculated retention time T by communication protected location from this trigger point again; If communication protection module fails to receive a trailing edge triggering signal in T time, then TEN becomes 0 after remaining the time T of 1 automatically.
Time constant T can be adjusted by the resistance and electric capacity regulating Schmidt trigger, like this, can adjust the different communication time delayed turn-off time for different communication speeds.
Communication isolation module plays the effect of the external communication circuit of isolation host CPU module in this programme.In the present invention; after being isolated by communication signal, the input of incoming communication protection module is very important; because only in this way could both achieve prevents RS485 bus from accounting for dead fault; effectively isolate again host CPU module and outside RS485 communication line, prevented the exception on communication line from disturbing and cause instrument abnormal operating state.
Monostable trigger-action circuit is not limited to the Schmidt trigger described in embodiment of the present invention; also has the equivalent replacement circuit of alternate manner; as the present embodiment; for those skilled in the art; make some equivalent alternative or obvious modification without departing from the inventive concept of the premise; and performance or purposes identical, all should be considered as belonging to the scope of patent protection that claims that the present invention submits to are determined.
Claims (5)
1. possess Phototube Coupling and prevent RS485 communication bus from accounting for the electric instrument of dead fault function, comprise host CPU module, AC current-voltage input module, memory module, communication isolation module, communication protection module, RS485 communication interface module, power module and indicator light;
Described host CPU module is used for carrying out sampling to the AC signal of input and calculates, and obtains the various electric power data of electric instrument, receives the communication packet of RS485 communication interface module simultaneously, and sent by RS485 communication interface module by response message;
Described AC current-voltage input module is used for changing AC current-voltage signal;
Described memory module is used for stores meter configuration information, as address, tuning parameter etc.;
Described communication isolation module is used for carrying out Phototube Coupling to the communication signal of host CPU module, and the communication signal of host CPU module comprises communication and sends signal TXD and communication Received signal strength RXD;
Described communication protection module, for safeguarding the reiving/transmitting state of RS485 communication interface, prevents RS485 communication interface to be in transmission state for a long time and causes accounting for of RS485 communication bus dead;
Described RS485 communication module is for realizing the conversion of RS485 signal;
It is characterized in that:
Described communication protection module sends signal trailing edge by the communication of host CPU module and triggers, automatically, will " send " signal enable and be set to 1, make RS485 communication interface module state auto-switching to transmission state, can output on RS485 communication bus so that the communication of host CPU module sends signal;
Described communication protection module is after the communication of host CPU module sends and stops, and time delay T millisecond automatically will " send " signal afterwards enable and be set to 0, thus RS485 communication interface module is switched to accepting state;
The trailing edge that described communication protection module sends signal by the communication of host CPU module triggers, and send time delay T millisecond when signal keeps certain level in communication just to automatically shut down, can effectively prevent the transmission enable signal caused as CPU exception or circuit abnormality be in the normal state 1 state;
Described communication protection module can utilize the communication of CPU module to send signal and automatically produce " sending enable " signal, need not the transmission of CPU module controls RS485 communication and accepting state, can reduce communication and isolate cost;
Host CPU module and external communication interface can be kept apart by described communication isolation module, external communication line is avoided to disturb the normal work of host CPU module, meanwhile, when multiple instrument shares a RS485 communication bus, make the isolated from power between each instrument, prevent potential safety hazard.
2. possess Phototube Coupling as claimed in claim 1 and prevent RS485 communication bus from accounting for the electric instrument of dead fault function, it is characterized in that:
Described communication protection module is made up of a monostable trigger-action circuit, and its output pulse width T can regulate;
Described communication protection module input control end is that the communication of the host CPU module of isolating through communication isolation module sends signal TXD, adopts trailing edge to trigger;
Described communication protection module output signal sends enable signal TEN for RS485, directly accesses RS485 interface chip and sends enable pin;
TEN is set to 1 by described communication protection module after receiving TXD signal trailing edge first; If again do not receive TXD signal trailing edge in T time, then TEN automatic resetting is 0; If again receive TXD signal trailing edge in T time, then making it export pulse, to be extended to TEN automatic resetting after this trailing edge T be 0.
3. possess Phototube Coupling as claimed in claim 2 and prevent RS485 communication bus from accounting for the electric instrument of dead fault function, it is characterized in that:
The monostable trigger-action circuit of described communication protection module can adopt hardware mode to form, and hardware timer mode also can be adopted to form.
4. possess Phototube Coupling as claimed in claim 2 and prevent RS485 communication bus from accounting for the electric instrument of dead fault function, it is characterized in that:
Described communication protection module communication sends signal TXD as sending enable triggering signal, eliminates CPU communication control enable signal and corresponding isolating chip in prior art.
5. possess Phototube Coupling as claimed in claim 1 and prevent RS485 communication bus from accounting for the electric instrument of dead fault function, be further characterized in that:
Described host CPU module is made up of MSP430 and peripheral circuit, and the communication signal of employing is communication signal TXD, RXD of the Universal Asynchronous Receive/dispensing device of MSP430 built-in chip type;
Described communication isolation module adopts photoelectric isolated chip 6N137, is isolated by TXD, RXD signal;
Described communication protection module adopts Schmidt trigger 74HC123, and the communication after isolation sends the trailing edge trigger pin of the Schmidt trigger 74HC123 of signal TXD incoming communication protected location; Adjustment Schmidt trigger 74HC123 outer meeting resistance electric capacity is adopted to regulate monostable trigger-action circuit output pulse width T; Its communication exported sends enable signal access RS485 communication interface module;
Described RS485 communication interface module is made up of RS485 level transferring chip 65LBC184 and peripheral overvoltage crowbar; It sends Enable Pin and is controlled by communication protection module, and output terminals A, the B of communication interface module receive on external communication circuit by the overvoltage crowbar of communication interface module;
Described indicator light comprises plant running indicator light, RS485 communication indicator light.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510782165.3A CN105357072A (en) | 2015-11-16 | 2015-11-16 | Electric power meter with functions of realizing optoelectronic isolation and preventing RS485 communication bus occupation faults |
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| CN201510782165.3A CN105357072A (en) | 2015-11-16 | 2015-11-16 | Electric power meter with functions of realizing optoelectronic isolation and preventing RS485 communication bus occupation faults |
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| CN105357072A true CN105357072A (en) | 2016-02-24 |
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| CN201510782165.3A Pending CN105357072A (en) | 2015-11-16 | 2015-11-16 | Electric power meter with functions of realizing optoelectronic isolation and preventing RS485 communication bus occupation faults |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106600944A (en) * | 2016-12-21 | 2017-04-26 | 安溪钟泰专利技术转移有限公司 | Remote meter reading system based on RS485 bus |
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Address after: 310053 Zhejiang city of Hangzhou province high and New Technology Industrial Park, Jiang Dongxin Road No. 69 building 4 Building 801 room 8 Applicant after: Hangzhou Gaea Electric Co., Ltd. Address before: Hangzhou City, Zhejiang Province, Binjiang District Jiangnan Road 310053 No. 3880 Huarong Times Building 15 Jiahe Electric Company Applicant before: Hangzhou Gaea Electric Co., Ltd. |
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Application publication date: 20160224 |
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