CN209844957U

CN209844957U - Cable analog circuit

Info

Publication number: CN209844957U
Application number: CN201921051844.3U
Authority: CN
Inventors: 王庆青; 史君梅; 郜联国
Original assignee: Zhengzhou Addie Science And Technology Co Ltd
Current assignee: Zhengzhou Addie Science And Technology Co Ltd
Priority date: 2019-07-05
Filing date: 2019-07-05
Publication date: 2019-12-24
Anticipated expiration: 2029-07-05

Abstract

The utility model relates to a cable analog circuit, this cable analog circuit connects between 485 bus communication unit and application terminal, include the first inductance and the first resistance between the A port of the serial connection in 485 bus communication unit and the first port of application terminal through the first connecting wire, the second connecting wire that both ends are connected with the B end of the 485 bus communication unit, the second end of application terminal respectively and connect the first electric capacity between first connecting wire and second connecting wire, the junction of first electric capacity and first connecting wire is in the low reaches of first inductance and first resistance; the inductance of the first inductor is 0.5-1.5 mH, the resistance of the first resistor is 19-27 omega, and the capacitance of the first capacitor is 103-105 pF; the cable simulation circuit is small in size, can be assembled in any equipment, is practical in function, reliable in work, easy to carry, can be used in any scene, and can be repeatedly used, low in cost and greatly reduce the detection cost.

Description

Cable analog circuit

Technical Field

The utility model belongs to the technical field of the communication, concretely relates to cable analog circuit and application thereof.

Background

With the wide application of the RS-485 bus protocol in the field of industrial communication, the use of RS-485 chips is gradually increased. At present, the 485 bus communication unit is divided into two-wire system and four-wire system connections, wherein two-wire system connection is mostly adopted, in general, RS-485 signals are decomposed into two positive and negative symmetric lines, i.e. conventional A, B signal lines, before reaching the receiving end, the signals are subtracted to restore the original signals. When the device is used, one end of the A, B signal line is correspondingly connected with the signal pin A, B of the 485 communication chip, and the other end is correspondingly connected with the communication interface of the application terminal. The maximum unrepeatered transmission distance of the RS-485 cable is 1200 meters, and in practice, the transmission distance can reach 1800 meters by adopting a special cable with impedance matching and low attenuation.

The 485 bus communication unit that commonly uses includes 485 chips and peripheral circuit, 485 communication bus unit is after certain time, communication distance can be shortened because of 485 chips or surrounding component performance decline distance, communication distance can not reach all of requirement and regard as unqualified, when detecting 485 chips or surrounding component performance, usually use 2 kilometers of cable to detect, will use cable connection control terminal and detection terminal, but the cable of this kind of major length obviously is more occupation space in the testing process, comparatively inconvenient.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming prior art not enough and providing a cable analog circuit that uses when detecting 485 chips or surrounding component performance carries out the cable analog circuit that replaces, uses this cable analog circuit's PCB board and uses this cable analog circuit's 485 communication performance detector.

The utility model provides a cable analog circuit, this cable analog circuit connect between 485 bus communication unit and application terminal, include first inductance and first resistance, the second connecting wire that both ends are connected with the B end of 485 bus communication unit, the second end of application terminal respectively and connect the first electric capacity between first connecting wire and second connecting wire through first connecting wire series connection between the A port of 485 bus communication unit and the first port of application terminal, the contact of first electric capacity and first connecting wire is in the low reaches of first inductance and first resistance;

the inductance of the first inductor is 0.5-1.5 mH, the resistance of the first resistor is 19-27 omega, and the capacitance of the first capacitor is 103-105 pF.

Further, the inductance of the first inductor is 1mH, the resistance of the first resistor is 18 Ω, and the capacitance of the first capacitor is 104 pF.

Further, the inductance of the first inductor is 0.5mH, the resistance of the first resistor is 9 Ω, and the capacitance of the first capacitor is 52 pF.

The utility model also provides a PCB board is equipped with above-mentioned cable analog circuit on this PCB board.

Furthermore, be provided with the fixed orifices on the PCB board, the relative both sides of PCB board are provided with binding post, the both ends of first connecting wire, second connecting wire link to each other with the binding post of both sides respectively.

Furthermore, the PCB is provided with more than 2 cable analog circuits, and the cable analog circuits are independent from each other.

Further, the parameters of the electronic components in each cable analog circuit are different.

The utility model also provides a 485 communication performance detector of using above-mentioned cable analog circuit and above-mentioned PCB board, this 485 communication performance detector include that detector box body, lid establish the lid on a terminal surface of detector box body, the fixed orifices that corresponds the PCB board in the box of detector box body is provided with the screw hole post that is used for fixed PCB board, it is provided with the plug wire hole to correspond binding post on the curb plate of detector box body.

Furthermore, the box cover is assembled on the detector box body in a sealing mode.

Furthermore, the side plate of the detector box body is provided with a dustproof plug corresponding to the wire insertion hole.

Compared with the prior art, the beneficial effects of the utility model are that:

compared with a cable for detection of a 485 bus communication unit, under the same impedance, the volume of the cable analog circuit is less than 50 times of the volume of a cable with the same length, the cable analog circuit can be assembled in any equipment, and the volume of an object for detection is greatly reduced.

Compared with the detection cost of using the cable, the cable simulation circuit has the advantages that the elements are easy to purchase, low in cost and reusable, and the detection cost can be greatly reduced;

the cable simulation circuit is practical in function, stable and reliable in performance after being verified for multiple times by cables with the same length, and capable of completely simulating the effect of the cables of 1-2 kilometers;

the 485 communication performance detector of this application is small in size, portable, and the function is used, and the reliable operation can simulate the effect of 1 ~ 2 kilometers cable completely, very big reduction the detection cost, removed the action of arrangement cable from, improved detection efficiency.

Drawings

Fig. 1 is a schematic circuit diagram of a cable analog circuit according to an embodiment of the present invention.

Fig. 2 is an application schematic diagram of a cable analog circuit according to an embodiment of the present invention.

Fig. 3 is the utility model discloses 485 communication performance detector's structural schematic.

Fig. 4 is the utility model discloses an application schematic diagram of 485 communication performance detector.

In the figure, a first inductor 1, a first resistor 2, a first capacitor 3, a second inductor 4, a second resistor 5, a second capacitor 6, a detector box body 7, a fixing hole 8, a wiring terminal 9, a PCB 10, a control terminal 11, a 485 communication performance detector 12 and an application terminal 13.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

The cable runs too long, which is mainly manifested as an increase in line resistance, line capacitance, and line inductance, then, in the case of a fixed cable length, the line resistance, line capacitance, and line inductance should be fixed. The 485 communication is generally applied to most of 2 kilometers at the longest, and under the condition of no relay, the 1-2 kilometer fixed line resistance, line capacitance and line inductance are connected by the cable simulation circuit, so that the length of the 1-2 kilometer cable can be simulated.

As shown in fig. 1, a cable analog circuit is connected between a 485 bus communication unit and an application terminal 13, and includes a first inductor 1 and a first resistor 2 connected in series between an a port of the 485 bus communication unit and a first port of the application terminal 13 through a first connection line, a second connection line having two ends connected to a B port of the 485 bus communication unit and a second end of the application terminal 13, respectively, and a first capacitor 3 connected between the first connection line and the second connection line, where a connection point of the first capacitor 3 and the first connection line is downstream of the first inductor 1 and the first resistor 2;

the inductance of the first inductor 1 is 0.5-1.5 mH, the resistance of the first resistor 2 is 19-27 omega, and the capacitance of the first capacitor 3 is 103-105 pF.

The first connection line corresponds to the a signal line described in the background art, a + is indicated at both ends of the first connection line in fig. 1, 2, and 4, the second connection line corresponds to the B signal line described in the background art, and B + is indicated at both ends of the second connection line in fig. 1, 2, and 4.

If the impedance of the test cable with 2 kilometers is simulated, the inductance of the first inductor 1 is 1mH, the resistance of the first resistor 2 is 18 omega, and the capacitance of the first capacitor 3 is 104 pF.

If the impedance of the test cable with the length of 1 kilometer is simulated, the inductance of the first inductor 1 is 0.5mH, the resistance of the first resistor 2 is 9 omega, and the capacitance of the first capacitor 3 is 52 pF.

As shown in fig. 1 to 3, the utility model also provides a PCB board, is equipped with above-mentioned cable analog circuit on this PCB board.

Preferably, as shown in fig. 3, the PCB is provided with a fixing hole, the two opposite sides of the PCB are provided with connecting terminals for facilitating connection, and two ends of the first connecting line and the second connecting line are respectively connected with the connecting terminals at the two sides; specifically, the wiring terminal is a PCB terminal.

Preferably, as shown in fig. 2 and 3, since the cable analog circuit is small in size and easy to integrate, in order to detect a plurality of 485485 bus communication units simultaneously and also facilitate saving of PCB resources, more than 2 cable analog circuits are arranged on the PCB, and the cable analog circuits are independent from each other and not connected to each other; preferably, the PCB is provided with 2 cable analog circuits.

Preferably, in order to simulate the impedance of cables with different lengths, the parameters of the electronic components in each cable analog circuit are different, and in particular, referring to fig. 2 and 3, in order to distinguish the electronic components in different cable analog circuits, the inductor, the capacitor and the resistor in the second cable analog circuit are respectively marked as a second inductor 4, a second resistor 5 and a second capacitor 6.

As shown in fig. 3, the utility model also provides a 485 communication performance detector applying the above-mentioned cable analog circuit and the above-mentioned PCB, the 485 communication performance detector includes a detector box body 7, a box cover covering on one end face of the detector box body 7, a threaded hole column for fixing the PCB is arranged in the box of the detector box body 7 corresponding to the fixing hole 8 of the PCB, a plug wire hole 14 is arranged on the side plate of the detector box body 7 corresponding to the connecting terminal, the box cover is not shown in the figure; preferably, the housing 7 and cover are made of an insulating material, such as ABS engineering plastic.

Preferably, the lid is sealingly mounted on detector box 7 to reach dustproof, waterproof purpose, if adopt modes such as buckle connection, encapsulating, sealing washer to carry out seal assembly.

Preferably, the side plate of the detector box body 7 is provided with a dust plug corresponding to the wire insertion hole 14, so that dust is prevented from entering the detector box body 7, the original impedance of the cable analog circuit is influenced, the impedance is increased, and the detection result of the 485 bus communication unit is prevented from being influenced; specifically, the dustproof stopper is the silica gel dustproof stopper that has the stopper post, and the dustproof stopper passes through the cord and connects on detector box body 7 to avoid the loss of dustproof stopper.

Specifically, as shown in fig. 4, when the 485 communication performance detector is used, a cable for detection is directly replaced, the 485 communication performance detector is directly connected between the control terminal 11 having the 485 bus communication unit or the 485 communication chip to be detected and the application terminal 13, and whether the 485 bus communication unit or the 485 communication chip is normal is judged by observing whether the communication between the control terminal and the application terminal 13 is normal or not.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.

Claims

1. A cable analog circuit connected between a 485 bus communication unit and an application terminal (13), characterized by: the device comprises a first inductor (1) and a first resistor (2) which are connected in series between an A port of a 485 bus communication unit and a first port of an application terminal (13) through a first connecting line, a second connecting line of which two ends are respectively connected with a B end of the 485 bus communication unit and a second end of the application terminal (13), and a first capacitor (3) connected between the first connecting line and the second connecting line, wherein the connection point of the first capacitor (3) and the first connecting line is positioned at the downstream of the first inductor (1) and the first resistor (2);

the inductance of the first inductor (1) is 0.5-1.5 mH, the resistance of the first resistor (2) is 19-27 omega, and the capacitance of the first capacitor (3) is 103-105 pF.

2. The cable analog circuit of claim 1, wherein: the inductance of the first inductor (1) is 1mH, the resistance of the first resistor (2) is 18 omega, and the capacitance of the first capacitor (3) is 104 pF.

3. The cable analog circuit of claim 1, wherein: the inductance of the first inductor (1) is 0.5mH, the resistance of the first resistor (2) is 9 omega, and the capacitance of the first capacitor (3) is 52 pF.

4. A PCB board, its characterized in that: provided with a cable analogue circuit according to any one of claims 1 to 3.

5. The PCB board of claim 4, wherein: the PCB is provided with a fixing hole, two opposite sides of the PCB are provided with wiring terminals, and two ends of the first connecting wire and the second connecting wire are connected with the wiring terminals on two sides respectively.

6. The PCB board of claim 4, wherein: the PCB is provided with more than 2 cable analog circuits which are independent from each other.

7. The PCB board of claim 6, wherein: the parameters of the electronic components in each cable analog circuit are different.

8. A485 communication performance detector using the PCB board of claim 4, wherein: establish the lid on a terminal surface of detector box body (7) including detector box body (7), lid, the fixed orifices (8) that correspond the PCB board in the box of detector box body (7) are provided with the screw hole post that is used for fixed PCB board, it is provided with plug wire hole (14) to correspond binding post on the curb plate of detector box body (7).

9. The 485 communication performance detector of claim 8, wherein: the box cover is assembled on the detector box body (7) in a sealing mode.

10. The 485 communication performance detector of claim 8, wherein: the side plate of the detector box body (7) is provided with a dustproof plug corresponding to the wire inserting hole (14).