CN104009856A - Apparatus and method for determining the location of a fault in a fieldbus network - Google Patents

Abstract

The invention discloses a device for determining the location of a fault in a field bus network, comprising: a switching module, used to switch the currently used baud rate of the field bus network to a predetermined The baud rate, the predetermined baud rate is lower than the baud rate currently used by the field bus network; the detection module is used to use the predetermined baud rate to detect the slave station working normally in the field bus network; And a determining module, configured to determine that the outside of the farthest slave station among the normally working slave stations is the location of the fault. By applying the embodiment of the present invention, the location of the fault in the field bus network can be quickly and accurately determined, thus avoiding the increase of system cost and making the research and development of the field bus network easier.

Description

Apparatus and method for determining the location of a fault in a fieldbus network

technical field

The invention relates to the field bus technology field, in particular to a device and a method for determining the location of a fault in a field bus network.

Background technique

Because the fieldbus network has the characteristics of strong environmental adaptability and interoperability, it is widely used in the field of industrial control. Among them, the widely used RS-485-based fieldbus includes process fieldbus-decentralized peripheral equipment (PROFIBUS-Decentralized Periphery, DP), foundation fieldbus & control and communication link system (Foundation Fieldbus & Control & Communication Link, CC-Link )wait. RS-485-based fieldbus uses twisted pair or coaxial cable as the transmission cable for signal transmission. The higher the baud rate used for transmission, the shorter the corresponding transmission distance. For the transmission with high baud rate, if no terminal resistance is added at both ends of the transmission cable, the fieldbus data signal will be reflected at the end of the transmission cable, thus submerging part of the fieldbus data signal and seriously affecting the performance of the fieldbus. communication quality, this phenomenon is also known as echo reflection. Therefore, it is necessary to add terminal resistance at both ends of the transmission cable to reduce the influence of echo reflection on the fieldbus data signal.

In practical applications, the faults in the fieldbus network mainly include terminal resistor faults and transmission cable faults. For example, the terminating resistor is not configured correctly at both ends or one end of the transmission cable, or the transmission cable is disconnected, etc. In order to maintain the fieldbus network, it is necessary to determine the location of the fault in time and accurately.

In the existing fault detection method, the self-diagnosis function of the fieldbus device can determine the location of the fault point through the diagnostic information. However, the self-diagnosis function is usually only used in short-distance transmission. When the transmission distance is long, the self-diagnosis function will be seriously affected by echo reflection, and the location of the fault point cannot be accurately determined. In order to accurately determine the location of the fault point in the fieldbus network, it is usually necessary to use a dedicated hardware diagnostic device. When using some hardware diagnostic equipment, it is also necessary to cut off the power supply of the entire fieldbus network. However, the use of dedicated hardware diagnostic equipment will increase the cost of the system, and in the field of industrial control, it is difficult to power off the entire fieldbus network at any time.

It can be seen that according to the prior art, when determining the location of a fault in a fieldbus network, there is a lack of a detection method and device that can quickly and accurately determine the fault point without increasing the system cost.

Contents of the invention

Embodiments of the present invention provide a device and method for determining the location of a fault in a field bus network, which can quickly and accurately determine the location of a fault in the field bus network without increasing system cost.

Embodiments of the present invention provide the following technical solutions.

The device for determining the location of the fault in the field bus network provided by the embodiment of the present invention includes:

A switching module, configured to switch the baud rate currently used by the field bus network to a predetermined baud rate when a fault occurs in the field bus network, and the predetermined baud rate is lower than that currently used by the field bus network baud rate;

A detection module, configured to use the predetermined baud rate to detect slave stations working normally in the field bus network;

A determining module, configured to determine that the outside of the farthest slave station among the normally working slave stations is the location of the fault.

In one embodiment of the present invention, the predetermined baud rate is the lowest baud rate allowed in the fieldbus network.

In one embodiment of the present invention, the field bus network includes a repeater; the detection module is used to detect the normal Working slave.

In one embodiment of the present invention, the field bus network is a field bus network based on RS-485.

The method for determining the location of the fault in the field bus network provided by the embodiment of the present invention includes:

When a fault occurs in the fieldbus network, switching the baud rate currently used by the fieldbus network to a predetermined baud rate, the predetermined baud rate being lower than the baud rate currently used by the fieldbus network;

Utilizing the predetermined baud rate, detecting a slave station working normally in the field bus network;

It is determined that the outer side of the slave station located at the farthest end among the normally working slave stations is the location of the fault.

In one embodiment of the present invention, the predetermined baud rate is the lowest baud rate allowed in the fieldbus network.

In one embodiment of the present invention, the field bus network includes a repeater; the detection of the normal working slave station in the field bus network includes: detecting the field bus network via the repeater normal working slave station.

In one embodiment of the present invention, the field bus network is a field bus network based on RS-485.

It can be seen that in the embodiment of the present invention, when a failure of the field bus network is detected, the baud rate used by the field bus network is reduced, thereby reducing the impact of echo reflection on the field bus data signal, ensuring that the field bus The normal working slave stations in the bus network can all be detected, and then the location of the fault in the field bus network can be quickly and accurately determined. Since the location of a fault in the fieldbus network can be quickly and accurately determined without the use of hardware diagnostic equipment, system cost increases are avoided and development of the fieldbus network is made easier.

Description of drawings

Fig. 1 is a schematic diagram of the structure of a device for determining the location of a fault in a fieldbus network in an embodiment of the present invention.

Fig. 2 is a schematic diagram of determining the location of a fault in a fieldbus network in the prior art.

Fig. 3 is a schematic diagram of determining the location of a fault in a fieldbus network in an embodiment of the present invention.

Fig. 4 is a flowchart of a method for determining the location of a fault in a fieldbus network in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following examples are used to further describe the embodiments of the present invention in detail.

Fig. 1 is a schematic diagram of the structure of a device for determining the location of a fault in a fieldbus network in an embodiment of the present invention. As shown in FIG. 1 , the device for determining the location of a fault in a fieldbus network provided by an embodiment of the present invention includes a switching module 11 , a detecting module 12 and a determining module 13 .

Wherein, the switching module 11 is used to switch the baud rate currently used by the field bus network to a predetermined baud rate when a fault occurs in the field bus network, and the predetermined baud rate is lower than the currently used wave rate of the field bus network. special rate. Wherein, when the switching module 11 switches the baud rate, the existing way of switching the baud rate can be adopted, for example, the predetermined baud rate to be switched after the failure occurs is set by software, etc., which will not be repeated here.

The detection module 12 is used to detect the normally working slave stations in the field bus network by using the predetermined baud rate. Wherein, the detecting module 12 may adopt an existing method for detecting the slave station, for example, sending a special diagnostic frame on the transmission cable, etc., which will not be repeated here. In practical applications, the predetermined baud rate after switching by the switching module 11 can be the lowest baud rate allowed in the fieldbus network, so that the detection module can more accurately detect all normal working slave stations, further ensuring the detection the accuracy of the results.

The determination module 13 is used to determine that the outer side of the most remote slave station among the normally working slave stations is the location of the fault. Since the detection module 12 has detected all the slave stations that are working normally, the outermost slave station is the location of the fault.

According to the characteristics of the fieldbus network, when the baud rate used by the fieldbus network is low, the reflected signal is weak, and the echo reflection caused by the reflected signal has little impact on the fieldbus data signal, and can even be ignored. The higher the baud rate used by the network, the greater the effect of echo reflections on the Fieldbus data signal. The baud rate used by the fieldbus network in normal operation is usually relatively high. When the transmission cable or the terminal resistor fails, the terminal resistor cannot play its role, causing echo reflection to seriously affect the transmission of the fieldbus data signal.

According to the device for determining the location of the fault in the field bus network provided by the embodiment of the present invention, when a fault occurs, the switching module 11 reduces the baud rate currently used by the field bus network, thereby reducing the impact of echo reflection on the field bus data signal As a result, the detection module 12 can quickly and accurately detect all the normally working slave stations, and then the determining module 13 can determine that the outermost slave station among the normally working slave stations is the location of the fault. It can be seen that according to the embodiment of the present invention, the location of the fault in the fieldbus network can be quickly and accurately determined without using hardware diagnostic equipment, thereby avoiding increasing the system cost and making the research and development of the fieldbus network easier.

In the embodiment of the present invention, the field bus network may be a field bus network based on RS-485, or other field bus networks with the above-mentioned relationship between baud rate and echo reflection.

In the embodiment of the present invention, the device for determining the location of the fault in the fieldbus network can be located in the master station of the fieldbus network, and the switching module, detection module and determination module can be used as newly added function modules of the master station, or the switching module , the detection module and the determination module can also be integrated in an independent functional module to realize the function of determining the fault location device in the fieldbus network.

Taking the PROFIBUS-DP network as an example, the device for determining the fault location in the field bus network provided by the embodiment of the present invention will be described in detail below. In this embodiment, the device for determining the location of the fault in the fieldbus network is located in the master station of the fieldbus network, and the switching module, detection module and determination module are newly added functional modules of the master station. The predetermined baud rate in the embodiment is the lowest baud rate allowed by the PROFIBUS-DP network, that is, 9.6 kbps.

In PROFIBUS-DP network, the relationship between baud rate and transmission distance is shown in Table 1.

Table 1

baud rate Transmission distance (m) 9.6kbps～187.5kbps 1000 500kbps 400 1.5Mbps 200 3Mbps～12Mbps 100

In practical applications, the PROFIBUS-DP network usually works at a high baud rate. In this embodiment, the PROFIBUS-DP network works at a baud rate of 1.5 Mbps.

Fig. 2 is a schematic diagram of determining the location of a fault in a fieldbus network in the prior art. As shown in Fig. 2, the transmission cable between the slave station 5 and the slave station 6 is disconnected, resulting in the failure of the PROFIBUS-DP network. The master station in the prior art can use the self-diagnosis function to determine the location of the fault. However, due to the strong echo reflection, the reception of the fieldbus data signal by the master station is affected. The master station can only detect slave station 1 to slave station 3, and cannot accurately determine the location of the fault. The outer side is identified as the location of the fault.

Fig. 3 is a schematic diagram of determining the location of a fault in a fieldbus network in an embodiment of the present invention. As shown in Figure 3, the fault of the PROFIBUS-DP network is still located between the slave station 5 and the slave station 6. When the switching module in the master station detects the fault, it switches the baud rate 1.5Mbps currently used by the fieldbus network to The predetermined baud rate is 9.6kbps. The detection module uses the predetermined baud rate to detect the slave station. Since the value of the predetermined baud rate is small, the impact of echo reflection on the fieldbus data signal is negligible, so the detection module can accurately detect all slave stations that are working normally, that is, slave station 1 to slave station 5 . The determining module determines the outer side of the farthest slave station among the normally working slave stations, that is, the outer side of the slave station 5, as the location of the fault, so as to obtain an accurate location of the fault.

When applying the embodiment of the present invention, when the transmission distance required by the fieldbus network is longer than the longest transmission distance (1000 meters) allowed by the PROFIBUS-DP network, the transmission distance can be extended by repeaters, each The transmission distance that can be extended by the repeater is also 1000 meters. At this time, the master station can detect the normally working slave stations in the fieldbus network through the repeater. Since the repeater does not affect the transmission rate and other performances of the entire network, the master station can still detect the normal working slave stations in the entire fieldbus network extended by the repeater.

It can be seen that according to the embodiment of the present invention, the location of the fault in the fieldbus network can be quickly and accurately determined without using a dedicated hardware diagnostic device, thereby avoiding increasing system costs and making the development of the fieldbus network easier.

Correspondingly, the embodiment of the invention also discloses a method for determining the fault location in the field bus network.

Fig. 4 is a flowchart of a method for determining the location of a fault in a fieldbus network in an embodiment of the present invention. As shown in FIG. 4 , the method for determining the fault location in the fieldbus network in this embodiment includes the following steps.

Step 41, when the master station detects that a fault occurs in the fieldbus network, switch the currently used baud rate of the fieldbus network to a predetermined baud rate, which is lower than the currently used baud rate of the fieldbus network .

Preferably, the predetermined baud rate is the lowest baud rate allowed in the field bus network, so as to reduce the impact of echo reflection on the field bus data signal as much as possible.

In step 42, the master station uses the predetermined baud rate to detect slave stations working normally in the field bus network.

When the predetermined baud rate is the lowest baud rate allowed in the field bus network, the impact of echo reflection on the field bus data signal is minimized, so that the master station can more accurately detect all normal working slave stations , to further ensure the accuracy of the detection results.

When the field bus network includes a repeater, in this step the master station can detect all normally working slave stations in the field bus network through the repeater.

In step 43, the master station determines that the outside of the farthest slave station among the normally working slave stations is the location of the fault.

In this embodiment, the above steps are performed by the master station in the fieldbus network, and in practical applications, the above steps can also be performed by independent functional modules.

In the embodiment of the present invention, the field bus network may be a field bus network based on RS-485, or other field bus networks with the above-mentioned relationship between baud rate and echo reflection.

It can be seen that, according to the embodiment of the present invention, when a fault occurs, the baud rate currently used by the fieldbus network is reduced, thereby reducing the impact of echo reflection on the fieldbus data signal, so that all normal operations can be performed quickly and accurately. The secondary stations of the system can be detected, and then it can be determined that the outer side of the remotest slave station among the normal working slave stations is the location of the fault. It can be seen that according to the embodiment of the present invention, the location of the fault in the fieldbus network can be quickly and accurately determined without using hardware diagnostic equipment, thereby avoiding increasing the system cost and making the research and development of the fieldbus network easier.

The invention discloses a device for determining the location of a fault in a field bus network, comprising: a switching module, used to switch the currently used baud rate of the field bus network to a predetermined The baud rate, the predetermined baud rate is lower than the baud rate currently used by the field bus network; the detection module is used to use the predetermined baud rate to detect the slave station working normally in the field bus network; A determining module, configured to determine that the outside of the farthest slave station among the normally working slave stations is the location of the fault. By applying the embodiment of the present invention, the location of the fault in the field bus network can be quickly and accurately determined, thus avoiding the increase of system cost and making the research and development of the field bus network easier.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Appropriate improvements can be made to the preferred embodiments according to the present invention in the specific implementation process, so as to meet the specific needs of specific situations. Therefore, it can be understood that the specific implementation manners of the present invention described herein are only exemplary, and are not intended to limit the protection scope of the present invention.

Claims (8)

1. A device for determining the location of a fault in a field bus network, characterized in that it comprises: A switching module, configured to switch the baud rate currently used by the field bus network to a predetermined baud rate when a fault occurs in the field bus network, and the predetermined baud rate is lower than that currently used by the field bus network baud rate; a detection module, configured to detect a normally working slave station in the fieldbus network by using the predetermined baud rate; and A determining module, configured to determine that the outside of the farthest slave station among the normally working slave stations is the location of the fault. 2. The device according to claim 1, wherein the predetermined baud rate is the lowest baud rate allowed in the fieldbus network. 3. The device according to claim 1, wherein a repeater is included in the field bus network; The detection module is used to detect the slave stations in the field bus network that work normally by using the predetermined baud rate through the repeater. 4. The device according to claim 1, wherein the field bus network is a field bus network based on RS-485. 5. A method for determining the location of a fault in a fieldbus network, comprising: When a fault occurs in the fieldbus network, switching the baud rate currently used by the fieldbus network to a predetermined baud rate, the predetermined baud rate being lower than the baud rate currently used by the fieldbus network; Utilizing the predetermined baud rate, detecting a slave station working normally in the field bus network; It is determined that the outer side of the slave station located at the farthest end among the normally working slave stations is the location of the fault. 6. The method according to claim 5, wherein the predetermined baud rate is the lowest baud rate allowed in the fieldbus network. 7. The method according to claim 5, wherein a repeater is included in the fieldbus network; The detecting the normally working slave stations in the field bus network includes: detecting the normally working slave stations in the field bus network via the repeater. 8. The method of claim 5, wherein the fieldbus network is an RS-485 based fieldbus network.