Profibus-DP bus fault detection model and method based on measured voltage

Abstract

The invention belongs to the technical field of industrial field bus fault detection, and discloses a Profibus-DP bus fault detection model and a Profibus-DP bus fault detection method based on measurement voltage, and the specific technical scheme is as follows: in a Profibus-DP bus network, each station is accessed to the Profibus-DP bus network through a bus connector, a terminal resistor is integrated in the bus connector, and the terminal resistor is connected with the Profibus-DP bus network; whether the terminal resistor is connected or not is controlled through the dial switch, the on-off condition of the dial switch connected to each station is set, the fault type of the Profibus-DP bus is judged by detecting the direct-current voltage through the universal meter, an operator can conveniently and timely check faults, operation is easy, the idea is clear, and the Profibus-DP bus fault detection device is very suitable for common field maintenance personnel.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial field bus fault detection, and in particular relates to a Profibus-DP bus fault detection model and method based on voltage measurement. Background Art

[0002] In industrial control, the Profibus-DP fieldbus network has the characteristics of high-speed and low-cost communication. It is one of the most widely used fieldbus networks and usually uses twisted pair cables for communication. In the use of the Profibus-DP fieldbus, design defects, construction defects, long use time, complex environment and other reasons may cause the Profibus-DP bus network to fail, affecting industrial production. Once the Profibus-DP bus network fails, it is required to check and deal with it as soon as possible. The Profibus-DP bus network often has many stations, and the fault manifestations are various. It is often difficult to lock the source of the fault.

[0003] The methods currently used include logical judgment method, resistance measurement method, handheld bus physical tester test, network diagnostic instrument test, system software diagnosis method, etc. The logical judgment method is to use alternative methods to judge and confirm whether there is a problem with suspected faulty cables, plugs, etc. The disadvantage of this method is that it requires spare parts for testing. The resistance measurement method determines the fault by measuring the bus resistance. The disadvantage of this method is that the power supply of all stations in the Profibus-DP bus network must be turned off, which will affect production. The handheld bus physical tester test can easily complete the inspection of bus cable disconnection faults, short circuit faults, and voltage fluctuations, but the disadvantage is that the measurement must be performed when the power is turned off and the cable is disassembled. The network diagnostic instrument test performs network fault diagnosis by testing network waveforms and telegram analysis. The disadvantage is that the operator needs to have relatively deep network knowledge and long-term experience accumulation. The system software diagnosis method uses the diagnostic function of the system software to analyze the Profibus-DP bus network. The disadvantage of this method is that the system diagnostic code is not easy to understand and is not suitable for ordinary on-site maintenance personnel. Summary of the invention

[0004] In order to solve the technical defects of the existing Profibus-DP bus fault detection method, such as the need to shut down the power of all stations in the Profibus-DP bus network when detecting a fault, the need to disconnect the cables, and the need for the operator to have relatively deep network knowledge and long-term experience accumulation, the present invention provides a Profibus-DP bus fault detection method based on voltage measurement, which overcomes many shortcomings of the existing Profibus-DP bus fault detection method. The method is simple to operate, has clear ideas, and is very suitable for ordinary on-site maintenance personnel.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a Profibus-DP bus fault detection model based on voltage measurement, in the Profibus-DP bus network, each station is connected to the Profibus-DP bus network through a bus connector, the bus connector is provided with a 9-pin plug, the pin 6 of the bus connector is connected to a +5V voltage, and the pin 5 of the bus connector is connected to a 0V voltage;

[0006] Pin 8 of the bus connector is connected to data line A, and pin 3 of the bus connector is connected to data line B;

[0007] The pin 5 of the bus connector is electrically connected to one end of the first pull-up resistor, and the other end of the first pull-up resistor is electrically connected to one end of the DIP switch and the terminal resistor respectively;

[0008] The pin 6 of the bus connector is electrically connected to one end of the second pull-up resistor, and the other end of the second pull-up resistor is electrically connected to the other end of the DIP switch and the terminal resistor respectively;

[0009] The incoming line terminal is provided with A1 terminal and B1 terminal, and the outgoing line terminal is provided with A2 terminal and B2 terminal;

[0010] Use the DIP switch to control whether to use the terminal resistor. When the DIP switch is turned to the ON position, the A1 terminal and the B1 terminal are connected to the terminal resistor, and the A2 terminal and the B2 terminal are disconnected from the terminal resistor.

[0011] When the DIP switch is turned to the OFF position, the A1 and B1 terminals are disconnected from the terminal resistor, while the A2 and B2 terminals are connected to the terminal resistor.

[0012] The resistance value of the first pull-up resistor is 390 ohms, the resistance value of the second pull-up resistor is 390 ohms, and the resistance value of the terminal resistor is 220 ohms.

[0013] In the Profibus-DP bus network, the connection method of the starting station and the terminal station is the same. The bus cable is connected to the incoming line end, and the two fiber cores of the bus are connected to the A1 terminal and B1 terminal of the incoming line end respectively. The DIP switch at the starting station is turned to the ON position, and the A1 terminal, B1 terminal and terminal resistor of the incoming line end are connected, and the A2 terminal and B2 terminal of the outgoing line end are disconnected;

[0014] The bus connected to the intermediate station is connected from the incoming line end and out from the outgoing line end, and the DIP switch is turned to the OFF position. The A1 terminal and B1 terminal of the incoming line end are disconnected from the terminal resistor, and the A2 terminal and B2 terminal of the outgoing line end are connected to the terminal resistor;

[0015] A terminal resistor is connected between the stations at the beginning and the end of the bus network to match the impedance on the bus and reduce signal attenuation. One end of the terminal resistor is connected to the reference 0 point of pin 5 through the first pull-down resistor, and the other end of the terminal resistor is connected to the 5V power supply positive voltage of pin 6 through the second pull-up resistor. When there is no station on the bus sending data, the first pull-down resistor, the terminal resistor and the second pull-down resistor ensure that there is a certain idle potential on the bus. Even if the dip switch on the bus connector is turned to the ON position, if the terminal station is not powered on, there is still no such certain idle potential on the terminal resistor, and the DP network will report an error.

[0016] Profibus-DP bus network DC voltage analysis and fault decision are as follows:

[0017] The DIP switches of the bus connectors at each intermediate station of the Profibus-DP bus network are required to be turned to the OFF position, which generally does not go wrong. However, the DIP switch positions of the bus connectors at the bus start and end stations are often wrong. The following analysis and fault decision are based on this.

[0018] Strategy 1: When the DC voltage between the B core and the A core of the Profibus-DP bus is detected to be 1.24V by a multimeter, in the Profibus-DP bus network, the dip switch on the bus connector at the starting site is turned to the ON position, and the dip switch on the bus connector at the terminal site is turned to the ON position, it is judged that the Profibus-DP bus is basically normal;

[0019] Strategy 2: When the DC voltage between the B core and the A core of the Profibus-DP bus is detected to be 1.1V by a multimeter, there are two fault conditions under this condition: Fault 1: It is determined that the DIP switch of the bus connector of the starting station is in the ON position, the power supply of the starting station is normal, and the DIP switch of the bus connector of the terminal station is in the OFF position; Fault 2: It is determined that the DIP switch of the bus connector of the starting station is in the OFF position, the DIP switch of the bus connector of the terminal station is in the ON position, and the power supply of the terminal station is normal;

[0020] Strategy three: When the multimeter detects that the DC voltage between the B core and the A core of the Profibus-DP bus is 0.62V, it is determined that the dip switch of the bus connector at the starting site is in the ON position, and the dip switch of the bus connector at the terminal site is in the ON position. Only one end is powered normally, and the other end is not powered normally. There are the following two fault conditions: Fault three: the starting site is powered normally, and the terminal site is not powered; Fault four: the starting site is not powered, and the terminal site is powered normally.

[0021] When a Profibus-DP bus fails and a multimeter is used to detect that the DC voltage between the Profibus-DP bus cores B and A is not any of the voltage values ​​in the above cases, a comprehensive analysis is required in combination with other methods for Profibus-DP bus failure.

[0022] Compared with the prior art, the present invention has the following specific beneficial effects: the present invention determines the Profibus-DP bus fault by detecting the DC voltage, the operation is simple, the idea is clear, and the present invention overcomes the shortcomings of the current Profibus-DP bus fault detection method, such as the need to shut down the power of all stations in the Profibus-DP bus network when detecting the fault, the need to disconnect the power cable, and the need for the operator to have relatively deep network knowledge and long-term experience accumulation, and is very suitable for ordinary on-site maintenance personnel to detect and determine the Profibus-DP bus fault. At the same time, the Profibus-DP bus fault diagnosis method based on voltage measurement of the present invention can quickly identify the cause of the bus fault, and take corresponding measures to quickly handle the fault, so that the bus quickly returns to normal, thereby minimizing the production loss caused by the Profibus-DP bus fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The following is a schematic diagram of the Profibus-DP bus network. R1 is the terminal resistance of the starting station, and R2 is the terminal resistance of the terminal station.

[0024] Figure 2 This is the schematic wiring diagram of the Profibus-DP bus connector.

[0025] Figure 3 This is the Profibus-DP bus DC equivalent circuit 1.

[0026] Figure 4 This is the Profibus-DP bus DC equivalent circuit 2.

[0027] Figure 5 Figure 3 is the DC equivalent circuit of Profibus-DP bus.

[0028] Figure 6 The figure is the Profibus-DP bus fault detection process based on voltage measurement. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] like Figure 1 , Figure 2 , Figure 6 As shown, a Profibus-DP bus fault detection model based on voltage measurement is shown. In the Profibus-DP bus network, each station is connected to the Profibus-DP bus network through a bus connector. The bus connector is provided with a 9-pin plug. Pin 6 of the bus connector is connected to a +5V voltage, and pin 5 of the bus connector is connected to a 0V voltage.

[0031] Pin 8 of the bus connector is connected to data line A, and pin 3 of the bus connector is connected to data line B.

[0032] The pin 5 of the bus connector is electrically connected to one end of the first pull-up resistor, and the other end of the first pull-up resistor is electrically connected to one end of the DIP switch and the terminal resistor respectively.

[0033] The pin 6 of the bus connector is electrically connected to one end of the second pull-up resistor, and the other end of the second pull-up resistor is electrically connected to the other end of the DIP switch and the terminal resistor respectively.

[0034] Among them, the resistance value of the first pull-up resistor is 390 ohms, the resistance value of the second pull-up resistor is 390 ohms, and the resistance value of the terminal resistor is 220 ohms.

[0035] The incoming line terminal is provided with A1 terminal and B1 terminal, and the outgoing line terminal is provided with A2 terminal and B2 terminal.

[0036] The use of the terminal resistor is controlled by the dip switch. When the dip switch is turned to the ON position, the A1 terminal and the B1 terminal are connected to the terminal resistor, and the A2 terminal and the B2 terminal are disconnected from the terminal resistor.

[0037] When the DIP switch is turned to the OFF position, the A1 and B1 terminals are disconnected from the terminal resistor, while the A2 and B2 terminals are connected to the terminal resistor.

[0038] Embodiment 1:

[0039] like Figure 3As shown in the figure, a Profibus-DP bus network of a factory is selected. Any bus connector on the Profibus-DP bus link to be tested is selected, and its side cover is removed to expose the A1 terminal and the B1 terminal first. The "gear selection switch" of the multimeter is set to the DC voltage gear, and the red and black test leads of the multimeter are respectively connected to the A1 terminal and the B1 terminal of the bus connector. The measured bus DC voltage is read from the multimeter indicator panel. The multimeter is used to detect that the DC voltage between the B core and the A core of the Profibus-DP bus is 1.24V, indicating that the ON / OFF switches of the bus connector of the starting station and the bus connector of the terminal station of the Profibus-DP bus are both turned to the "ON" position, and the power supply of the starting station and the terminal station is normal. The Profibus-DP bus is basically normal, which also indicates that the communication of the Profibus-DP bus is normal.

[0040] Embodiment 2:

[0041] like Figure 4 As shown in the figure, a communication failure occurs in the Profibus-DP bus network of a factory. Select any bus connector on the Profibus-DP bus link to be tested, and remove its side cover to expose the A1 terminal and B1 terminal first. Set the "gear selection switch" of the multimeter to the DC voltage gear, connect the red and black test leads of the multimeter to the A1 terminal and B1 terminal of the bus connector respectively, read the measured bus DC voltage from the multimeter indicator panel, and use the multimeter to detect that the DC voltage between the B core and the A core of the Profibus-DP bus is 1.1V, indicating that either the bus of the Profibus-DP bus starting station is faulty. The ON / OFF switch of the connector is in the "ON" position, the power supply of the starting site is normal, and the ON / OFF switch of the bus connector of the terminal site is in the "OFF" position; or the ON / OFF switch of the bus connector of the terminal site is in the "ON" position, the power supply of the terminal site is normal, and the ON / OFF switch of the bus connector of the starting site is in the "OFF" position; after inspection, the inspectors found that the ON / OFF switch of the bus connector of the terminal site was in the "OFF" position, so they turned the ON / OFF switch of the bus connector of the terminal site to the "ON" position, and the network communication returned to normal.

[0042] Embodiment three:

[0043] like Figure 5As shown, a communication failure occurred in the Profibus-DP bus network of a certain factory. Select any bus connector on the Profibus-DP bus link to be tested, and remove its side cover to expose the A1 terminal and B1 terminal first. Set the "gear selection switch" of the multimeter to the DC voltage gear, connect the red and black test leads of the multimeter to the A1 terminal and B1 terminal of the bus connector respectively, read the measured bus DC voltage from the multimeter indicator panel, and use the multimeter to detect that the DC voltage between the B core and the A core of the Profibus-DP bus is 0.62V, indicating that the ON / OFF switches of the bus connector at the starting station of the Profibus-DP bus and the bus connector at the terminal station are both in the "ON" position, but only one end is powered normally, and the other end is not powered. After further inspection by the inspectors, it was found that the 24V power supply switch of the terminal station was tripped. The inspectors closed the power supply switch, and the network communication returned to normal.

[0044] Embodiment 4:

[0045] A communication failure occurred in the Profibus-DP bus network of a certain factory. Select any bus connector on the Profibus-DP bus link to be tested, and remove its side cover to expose the A1 terminal and B1 terminal first. Set the "gear selection switch" of the multimeter to the DC voltage gear, connect the red and black test leads of the multimeter to the A1 terminal and B1 terminal of the bus connector respectively, read the measured bus DC voltage from the multimeter indicator panel, and use the multimeter to detect that the DC voltage between the B core and the A core of the Profibus-DP bus is 0V. Further inspection using other methods found that the bus connector ON / OFF switch at the bus starting station was in the "OFF" position, and the bus connector ON / OFF at the bus terminal station was damaged. Therefore, the bus connector ON / OFF switch at the bus starting station was turned to the "ON" position, and the bus connector at the terminal station was replaced, and the network communication returned to normal.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A Profibus-DP bus fault detection model based on voltage measurement, characterized in that: In the Profibus-DP bus network, each station is connected to the Profibus-DP bus network through a bus connector. Pin 6 of the bus connector is connected to +5V voltage, and pin 5 of the bus connector is connected to 0V voltage. Pin 8 of the bus connector is connected to data line A, and pin 3 of the bus connector is connected to data line B; The pin 5 of the bus connector is electrically connected to one end of the first pull-up resistor, and the other end of the first pull-up resistor is electrically connected to one end of the DIP switch and the terminal resistor respectively; The pin 6 of the bus connector is electrically connected to one end of the second pull-up resistor, and the other end of the second pull-up resistor is electrically connected to the other end of the DIP switch and the terminal resistor respectively; The incoming line terminal is provided with A1 terminal and B1 terminal, and the outgoing line terminal is provided with A2 terminal and B2 terminal; When the DIP switch is turned to the ON position, the A1 and B1 terminals are connected to the terminal resistor, while the A2 and B2 terminals are disconnected from the terminal resistor. When the DIP switch is turned to the OFF position, the A1 and B1 terminals are disconnected from the terminal resistor, while the A2 and B2 terminals are connected to the terminal resistor.

2. A Profibus-DP bus fault detection model based on voltage measurement according to claim 1, characterized in that: The resistance value of the first pull-up resistor is 390 ohms, the resistance value of the second pull-up resistor is 390 ohms, and the resistance value of the terminal resistor is 220 ohms.

3. A Profibus-DP bus fault detection method based on voltage measurement, characterized in that: In the Profibus-DP bus network, the connection method of the starting station and the terminal station is the same. The bus cable is connected to the incoming line end, and the two fiber cores of the bus are connected to the A1 terminal and B1 terminal of the incoming line end respectively. The DIP switch at the starting station is turned to the ON position, and the A1 terminal, B1 terminal and terminal resistor of the incoming line end are connected, and the A2 terminal and B2 terminal of the outgoing line end are disconnected; The bus connected to the intermediate station is connected from the incoming line end, and the DIP switch is turned to the OFF position. The A1 terminal and B1 terminal of the incoming line end are disconnected from the terminal resistor, and the A2 terminal and B2 terminal of the outgoing line end are connected to the terminal resistor; A terminal resistor is connected between the stations at the beginning and end of the bus network to match the impedance on the bus. One end of the terminal resistor is connected to the reference 0 point of pin 5 through a first pull-down resistor, and the other end of the terminal resistor is connected to the 5V power supply positive voltage of pin 6 through a second pull-up resistor. When there is no station sending data on the bus, the first pull-down resistor, the terminal resistor and the second pull-down resistor ensure that there is a certain idle potential on the bus.

4. A Profibus-DP bus fault detection method based on voltage measurement, characterized in that: The specific detection strategy is as follows: Strategy 1: When the DC voltage between the B core and the A core of the Profibus-DP bus is detected to be 1.24V by a multimeter, in the Profibus-DP bus network, the dip switch on the bus connector at the starting site is turned to the ON position, and the dip switch on the bus connector at the terminal site is turned to the ON position, it is judged that the Profibus-DP bus is basically normal; Strategy 2: When the DC voltage between the B core and the A core of the Profibus-DP bus is detected to be 1.1V by a multimeter, there are two fault conditions: Condition 1: It is determined that the DIP switch of the bus connector of the starting station is in the ON position, the power supply of the starting station is normal, and the DIP switch of the bus connector of the terminal station is in the OFF position; Condition 2: It is determined that the DIP switch of the bus connector of the starting station is in the OFF position, the DIP switch of the bus connector of the terminal station is in the ON position, and the power supply of the terminal station is normal; Strategy 3: When the DC voltage between the B core and the A core of the Profibus-DP bus is detected to be 0.62V using a multimeter, it is determined that the dip switch of the bus connector at the starting site is in the ON position and the dip switch of the bus connector at the terminal site is in the ON position. There are two fault conditions: Condition 3: The starting site is powered normally, but the terminal site is not powered; Condition 4: The starting site is not powered, but the terminal site is powered normally.

Images