CAN bus application and fault detection? Chengdu Panfeng Technology

is the abbreviation of Controller Area Network (Controller Area Network), which was developed by a German company famous for the development and production of automotive electronics and eventually became an international standard. It is one of the most widely used fieldbuses in the world. In North America and Western Europe, the bus protocol has become the standard bus for automotive computer control systems and embedded industrial control LANs, and has a bottom-level protocol designed specifically for large trucks and heavy industrial machinery vehicles. In recent years, its high reliability and good error detection capabilities have attracted attention and are widely used in automotive computer control systems and industrial environments with harsh ambient temperatures, strong electromagnetic radiation and large vibrations. Chengdu Panfeng Technology is committed to the independent research and development of automotive electronics and bus network experimental development and training teaching equipment. It can provide product schematics and source programs for secondary development. Simulation recording of communication information can be simulated and sent! For more details, please call qq
How to identify and detect faults during application? ?
The bus detection method vehicle cannot be started.
First of all, observe the status of the vehicle when it cannot be started, mainly the instrument. Observe whether the instrument has power because the working status of other modules on the vehicle can be seen from the instrument. If the meter has no power, you can check it as follows. First check the status of the meter when it is out of power. Because the display of the instrument is controlled by the front control module and the top control module. At the same time, the rear control module also affects the instrument. After turning on the power switch, press the shift switch. Check to see if the switch connected to the bus on the car has power. If there is electricity, it means it is a problem with front control. This refers to all problems related to front control. Including front control wiring issues. If there is no power, it means there is a problem with the rear control. At this time, another method can be used to make a simple judgment. That is, whether there is power passing through the instrument when the power is turned on. Having electricity is a matter of front control. No power is a problem with the rear control.
When there is a display on the instrument on the car, it can be observed through the LCD screen of the instrument. The method is as follows: Press the up or down key under the instrument to find the module online interface. When the vehicle does not start, it may be caused by the axle module rear control module or front control module being disconnected. You can easily tell whether it is online by observing it. At the same time, the gear indicator light under the instrument does not light up when the axle is not online, and the gear light turns on when the rear control is not online. If the light below the instrument does not light up and the engine cannot start normally, check whether the communication line between the engine and the gearbox is short-circuited or open.
The starter can rotate but it just won't start. This is caused by a computer failure in the engine or a failure in the fuel supply system. The troubleshooting method is as follows: First, check whether the fuse of the module is burned out. Secondly, check whether the connector on the vehicle wiring harness is secure. Finally, check whether the wiring on the module has been disconnected. The signal from the engine cannot be transmitted to the bus. This is usually due to a problem with the interface between the engine and the bus. There are three interfaces in the car. One is in the front wiring harness, one is in the backup electrical box, and the other is on the side of the iron box above the engine. They are all self-locking connectors for shielded wires. Look for these plugs to see if there is a problem. The display of the instrument pressure gauge is inconsistent: the gas tank pressure sensor detects the pressure sensor in the gas tank and outputs an analog resistance signal, which is transmitted to the central control and then from the central control to the bus (the gas tank pressure sensor line number corresponds to the central control pin angle negative ground signal The line number is another gas tank pressure sensor. The line number corresponds to the pin-angle negative ground line. After the virtual resistance becomes infinite, the instrument pressure will reach the top. The resistance value of the gas tank pressure sensor at standard air pressure is ohms. Iveco oil pressure does not alarm. The parameters of the Weidi instrument module are lower than the alarm. When the Iveco engine is not started, the computer defaults to it. From this, it can be concluded that the Iveco engine oil pressure cannot be lower than the Weidi oil pressure alarm light does not light up and cannot be used in the oil. An alarm is provided when the pressure is low. Now Weidi will raise the alarm value to exceed the default oil pressure of the engine computer to ensure that the oil pressure alarm light is on when the engine is not running. The resistor cannot be connected in series because the Iveco engine sensor provides the signal to the Iveco computer and then transmits it to the Weidi module. During this time, the analog signal has been converted into a digital signal (no conversion is required). If the sensor directly sends the analog signal to the Weidi module, this can be corrected based on the principle of series resistance. mistake. The digital signal is a software alarm and the analog signal is a hardware alarm directly (the instrument alarm parameters are controlled by the rear control and the parameter needs to be adjusted when replacing the rear control). The LCD screen of the instrument always displays the rear hatch opening control. The module displayed on the LCD screen is the rear control module pin (the pins of the module of each vehicle model are inconsistent, please refer to the individual vehicle model agreement for details). When the rear hatch door is closed, the negative pole of the driving switch relay pull-in module is grounded. A signal is transmitted to the instrument module so that it does not indicate that the rear hatch is open. When the rear hatch is opened, the driving switch relay is disconnected and the negative ground signal of the module is suspended. The instrument module cannot receive the negative ground signal and the instrument often indicates that the rear hatch is open. For this kind of fault, you can disconnect the pins of the rear control module and connect it directly to see if it is solved. If it is solved, you can check whether the driving switch, relay, driving switch and the circuit are open. Chengdu Panfeng Technology is committed to the independent research and development of automotive electronics and bus network experimental development and training teaching equipment. It can provide product schematics and source programs for secondary development. Simulation recording of communication information can be simulated and sent! For more details, please call qq
The following two situations are module calibration protocol errors
If the instrument does not display the open status of the rear hatch after the pin gives a voltage signal, it means that the module is calibrated to give an output voltage Signal: When the line gives voltage, the rear control gives a signal to the instrument module through the bus so that it does not display the status of the rear door.
When the rear door is opened, the status of the rear door is not displayed. When the rear door is closed, the instrument displays that the rear door is open, indicating that the module is calibrated for a floating signal. When the relay is closed, the negative signal is turned on, causing the rear control module to The instrument module sends a signal to cause the instrument to display that the rear compartment door is open. After disconnecting, the rear control module sends a signal to the instrument so that it does not display the rear door status.
Chengdu Panfeng Technology is committed to the independent research and development of automotive electronics and bus network experimental development and training teaching equipment. It can provide product schematics and source programs for secondary development. Simulation recording of communication information can be simulated and sent! For more details, please call qq