CN202872757U

CN202872757U - RS485 photoelectric communication conversion device

Info

Publication number: CN202872757U
Application number: CN 201220620424
Authority: CN
Inventors: 袁维益
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-10-31
Filing date: 2012-10-31
Publication date: 2013-04-10
Anticipated expiration: 2022-10-31

Abstract

The utility model belongs to the field of electronic information technologies and communication technologies, and concretely discloses an RS485 photoelectric communication conversion device. The conversion device comprises an RS485 interface, an RS485 drive chip, an RS485 half-duplex direction control circuit and a TTL (transistor-transistor logic) level transmitting and receiving integrated optical module, wherein the RS485 drive chip is respectively connected with the RS485 interface, the RS485 half-duplex direction control circuit and the TTL level transmitting and receiving integrated optical module; and the TTL level transmitting and receiving integrated optical module is also connected with the RS485 half-duplex direction control circuit. The conversion device can realize the conversion between an RS485 difference electrical signal and an RS485 difference optical signal, and can effectively extend the communication distance of RS485 communication equipment.

Description

A kind of RS485 photoelectric communication conversion equipment

Technical field

The utility model belongs to electronic information technology and communication technical field, relates in particular to a kind of RS485 photoelectric communication conversion equipment.

Background technology

In recent years, the optical fiber new technology continue to bring out the application power that has increased substantially optical fiber, and constantly enlarge the range of application of optical fiber communication.Optical fiber communication has been widely used in all many-sides such as industry, electric power, military affairs, Aero-Space, biomedicine because of its good transmission characteristic.

Intelligence instrument is along with the maturation of singlechip technology at the beginning of the eighties grows up, and the world is monopolized by intelligence instrument in instrument market substantially now.Tracing it to its cause is exactly the needs of IT application in enterprises, and enterprise's one of them necessary condition when instrument selection will have the connected network communication interface exactly.Be data analog signal output simple procedure amount at first, instrumentation tap was the RS232 interface afterwards, and this interface can be realized point-to-point communication mode, but this mode can not realize network savvy.The RS485 that occurs has subsequently solved this problem.

The half-duplex network that the RS485 interface forms generally is two-wire system (the four-wire system connection was arranged in the past, can only realize point-to-point communication mode, existing seldom employing), adopts the Shielded Twisted Pair transmission more.This mode of connection is that the bus type topological structure can articulate at most 32 nodes on same bus.General employing is the master-slave communication mode in the RS485 communication network, i.e. a plurality of slaves of main frame band.In a lot of situations, just use simply a pair of twisted-pair feeder that " A ", " B " end of each interface are coupled together when connecting the RS-485 communication link.The RS485 interface connector adopts the 9 core plug seats of DB-9, adopts DB-9 (hole) with intelligent terminal RS485 interface, and the keyboard interface RS485 that is connected with keyboard adopts DB-9 (pin).

Other has a problem is signal ground, above-mentioned method of attachment is to work in many occasions, but buried very large hidden danger, this has two reasons: (1) common mode disturbances problem: the RS-485 interface adopts the differential mode signal transmission, need to not come detection signal with respect to certain reference point, the potential difference that system only need detect between two lines is just passable.But people have often ignored transceiver certain common-mode voltage range being arranged, RS-485 transceiver common-mode voltage range is-7～+ 12V, only have and satisfy above-mentioned condition, whole network could work.When common-mode voltage in the network line exceeds this scope, will affect the reliable and stable of communication, even damage interface.(2) EMI (Electro Magnetic Compatibility) problem: the common mode that sends in the driver output signal partly needs a return path, backward channel (signal ground) such as the neither one low-resistance, common mode part in the signal will be returned source with the form of radiation, and whole bus will look like the outside radiated electromagnetic wave of huge antenna.

Since PC acquiescence only with the RS232 interface, have two kinds of methods can obtain the RS485 circuit of PC host computer: (1) converts PC serial ports RS232 signal to the RS485 signal by the RS232/RS485 change-over circuit, preferably selects the product of Anti-surging band isolated gate for the industrial environment of situation more complicated.(2) by the PCI multi-serial-port card, can directly select output signal is the expansion card of RS485 type.

RS485 is a kind of communication standard that utilizes the differential transfer mode to increase communication distance and improve reliability, is widely used in the industrial instrument, but under the communications applications condition of longer distance, uses still very limited.

The utility model content

The technical problem that the utility model solves is to provide a kind of RS485 photoelectric communication conversion equipment, and this conversion equipment can be realized the mutual conversion of RS 485 differential electric signal and light signal, can effectively prolong the communication distance of RS 485 communication equipments.

For solving the problems of the technologies described above, the utility model adopts following technical scheme:

A kind of RS485 photoelectric communication conversion equipment, this conversion equipment comprise that RS485 interface, RS485 drive chip, RS485 half-duplex directional control circuit and Transistor-Transistor Logic level optical fiber transceiver module; Described RS485 drives chip and is connected with described RS 485 interfaces, RS 485 half-duplex directional control circuits, Transistor-Transistor Logic level optical fiber transceiver module respectively; Described Transistor-Transistor Logic level optical fiber transceiver module also is connected with RS 485 half-duplex directional control circuits.

Further, this conversion equipment inside also comprises the DC-DC power circuit for the internal circuit power supply.

Further, the SC interface, optical fiber that is provided with the Transistor-Transistor Logic level optical fiber transceiver module on the interface of this conversion equipment is changed indicator light, RS485 to optical fiber to RS485 and is changed indicator light, RS 485 communication interfaces, power input interface and power supply indicator.

Further, this conversion equipment is finished the switching of RS 485 half-duplex directions automatically by hardware.

Further, this conversion equipment also comprises power input interface and telecommunication cable, but described telecommunication cable supplying power for outside or from external electricity.

Compared to prior art, the beneficial effect of the utility model optical fiber RS 485 conversion equipments is: circuit is realized simple, can effectively reduce production costs; Power supply interface is flexible, but telecommunication cable supplying power for outside or from external electricity; And conversion equipment adopts pure hardware to realize, reliability is high, and RS 485 communications are half-duplex, and duplex directions is automaticallyed switch by hardware.

Description of drawings

The picture that this description of drawings provides is used for auxiliary to further understanding of the present utility model, consists of the application's a part, does not consist of to improper restriction of the present utility model, in the accompanying drawings:

Fig. 1 is the circuit structure schematic diagram of RS485 photoelectric communication conversion equipment described in the utility model.

Fig. 2 is the application schematic diagram of RS485 photoelectric communication conversion equipment described in the utility model when realizing distant signal transmission.

Embodiment

Describe the utility model in detail below in conjunction with accompanying drawing and specific implementation method, be used for explaining the utility model in schematic enforcement of the present utility model and explanation, but not as to restriction of the present utility model.

Embodiment 1

As shown in Figure 1, the utility model discloses a kind of RS485 photoelectric communication conversion equipment, it comprises that Transistor-Transistor Logic level optical fiber transceiver module 1, RS 485 half-duplex directional control circuits 2, RS485 drive chip 3, RS 485 communication interfaces 4 and DC-DC power circuit 5.

Wherein, described RS 485 drives chip 3 and is connected with RS 485 communication interfaces 4, RS 485 half-duplex directional control circuits 2, Transistor-Transistor Logic level optical fiber transceiver module 1 respectively, and Transistor-Transistor Logic level optical fiber transceiver module 1 drives chip 3 with RS 485 half-duplex directional control circuits 2, RS 485 respectively and is connected.

Wherein, described DC-DC power circuit 5 provides power supply for whole module.DC-DC namely is the meaning of DC-DC.

Wherein, the basic functional principle of described RS485 photoelectric communication conversion equipment is: RS 485 drives chip operation at the half-duplex state, when the Transistor-Transistor Logic level optical fiber transceiver module did not detect the light signal input, the half-duplex directional control circuit can be controlled RS 485 driving chip drives optical modules 485 differential signals are converted to light signal; When the Transistor-Transistor Logic level optical fiber transceiver module detected the light signal input, the half-duplex directional control circuit can be controlled RS 485 driving chips light signal is converted to 485 differential signals.

Wherein, described RS485 photoelectric communication conversion equipment is supported the mutual conversion of optical fiber and RS 485 half-duplex operations, and the SC interface, optical fiber that is provided with the Transistor-Transistor Logic level optical fiber transceiver module on the interface of this conversion equipment is changed indicator light, RS485 to optical fiber to RS485 and changed indicator light, RS 485 communication interfaces, power input interface and power supply indicator.

Wherein, the optical transceiver that the SC interface is used for the transmission network signal adopts the SC optical interface, and fundamental characteristics is as follows:

1, plug-type connection, fast and reliable;

2, volume is little, and is lightweight, but high-density installation

3, insertion loss is low, and return loss is high

4, adopt 1.25 ceramic contact pins

5, meet the IEC standard

Wherein, described Transistor-Transistor Logic level signal is that what to be utilized is at most because usually data representation adopts the binary system regulation, + 5V is equivalent to logical one, 0V is equivalent to logical zero, this is referred to as TTL (transistor-transistor logic level) signal system, and this is the standard technique of communicating by letter between the device interior each several part of computer processor control.

As shown in Figure 2, have 5 RS 485 equipment to link together and communicate, wherein the communication distance of equipment 1, equipment 3 and equipment 5 is far away, needs to prolong communication distance.Can be first the bus cable differential electric signal be converted to via RS485 photoelectric communication conversion equipment and be transferred to behind the light signal more at a distance, and then after another RS485 photoelectric communication conversion equipment changes 485 differential electric signal into, be connected on the corresponding RS485 equipment.

In order to overcome the application restric-tion of RS485 under longer communication distance condition, the RS 485 photoelectric communication conversion equipments that the utility model provides can be realized the mutual conversion of RS 485 differential signals and light signal, can effectively prolong the communication distance of RS485 communication equipment, and its circuit is realized simple, can effectively reduce production costs; Power supply interface is flexible, but telecommunication cable supplying power for outside or from external electricity; And conversion equipment adopts pure hardware to realize, reliability is high, and RS 485 communications are half-duplex, and duplex directions is automaticallyed switch by hardware.

More than technical scheme that the utility model embodiment is provided be described in detail, used specific case herein principle and the execution mode of the utility model embodiment are set forth, the explanation of above embodiment is only applicable to help to understand the principle of the utility model embodiment; Simultaneously, for one of ordinary skill in the art, according to the utility model embodiment, all will change on embodiment and range of application, in sum, this description should not be construed as restriction of the present utility model.

Claims

1. RS485 photoelectric communication conversion equipment is characterized in that:

This conversion equipment comprises that RS485 interface, RS485 drive chip, RS485 half-duplex directional control circuit and Transistor-Transistor Logic level optical fiber transceiver module;

Described RS485 drives chip and is connected with described RS 485 interfaces, RS 485 half-duplex directional control circuits, Transistor-Transistor Logic level optical fiber transceiver module respectively;

Described Transistor-Transistor Logic level optical fiber transceiver module also is connected with RS 485 half-duplex directional control circuits.

2. RS485 photoelectric communication conversion equipment according to claim 1 is characterized in that:

This conversion equipment inside also comprises the DC-DC power circuit for the internal circuit power supply.

3. RS485 photoelectric communication conversion equipment according to claim 1 is characterized in that:

The SC interface, optical fiber that is provided with the Transistor-Transistor Logic level optical fiber transceiver module on the interface of this conversion equipment is changed indicator light, RS485 to optical fiber to RS485 and is changed indicator light, RS 485 communication interfaces, power input interface and power supply indicator.

4. RS485 photoelectric communication conversion equipment according to claim 1 is characterized in that:

This conversion equipment is finished the switching of RS 485 half-duplex directions automatically by hardware.

5. RS485 photoelectric communication conversion equipment according to claim 1 is characterized in that:

This conversion equipment also comprises power input interface and telecommunication cable, but described telecommunication cable supplying power for outside or from external electricity.