What to begin with? How to find, extract and parse data from CAN bus? We have prepared 9 useful tips for those who want to make the first steps.
1. Begin with turn signals
Start mastering the tool by searching such simple parameters as: blinkers, the position of the steering wheel or doors. The simpler the action, the easier it is to influence the values change in the system. This means that you can quickly determine the right indicator among many others.
2. The more important, the closer to the top of the list
More than two thousand messages are transmitted on CAN bus at the speed up to 1 Mbit/s. How to find necessary data among such a volume?
Engine speed data, gas pedal position, and ABS sensors values are often at the top of the ID list, as they are crucial to transmission and safety systems. At the same time, info about wipers or trunk lid is not a priority for proper system work. It is more likely to appear at the bottom of the ID list.
So, the more important the element you are trying to receive data from, the higher it is located in the ID list. Act physically on the mechanical unit and look for indicator changes in the line, appropriate to its importance.
3. Change the highlight period
How to spot the changing parameters online and compare the data second per second? Use the slider in the upper right corner to choose a longer period for highlighting the indicators.
By default, it is set to instant data updating. However, if you know that the unit you are trying to influence, changes indicators less often, set a longer period, for example, 5 or 7 seconds.
Wait until all the indicators turn gray and start physical action on the required indicator. Probably you can quickly find changes among the rest. This will help you to filter out unnecessary indicators and concentrate on the definite ID.
For example, engine speed data changes every second, in contrast to the fuel level, which is almost always the same at rest.
Therefore, looking at the ID list, you are more likely to spot changes in RPM than in fuel level. Thus, increase the highlight time and begin to act on the indicators of the required unit.
4. Remove unnecessary indicators
During data identification, you can separate or filter out those ID lines, that contain unnecessary information. Just click on the eye icon, and this line will move to the bottom of the list. You can get it back by pressing the crossed eye icon again.
5. Copy the same ID line
Sometimes one ID line contains data from several elements. For instance, information about low/high beam or tailing lamps is located in adjacent bytes.
If you need to send or copy this data, then put a tag to this ID. To do this, copy the ID line and sort the required bytes into different tags. It’s for your convenience.
6. Bytes – from left to right and vice versa
In CAN Scanner data is displayed in the hexadecimal system. However, in the case of processing more than one byte, you face the problem of reading data in different formats: from oldest to youngest and vice versa. CAN scanner allows selecting the direction of reading data before writing into the tag and sending it to the server. Highlight the required bytes and choose the direction of reading at the end of the line, then specify the tag, where the data should be written.
7. Start recording in advance
If you do not have enough time to find all data at that time, then you can use logging. Affect the data, save the log for further playback numerous times. It is better to start logging before any action on the vehicle is performed. So that moment of the beginning and the end of the action is displayed in the log. It is much better than a short piece of the log taken out of context. In order not to get confused with the data, use the color zones. We tell about them in the next paragraph.
8. Color zones for easy decryption
Use color markers to allocate the period of the log recording to search the required ID. For example, in the log record, mark in yellow the period when you changed engine speed, in red - when you pressed the brake pedal, in green - opened or closed the trailer gates.
This will help you with further decryption. You do not have to look for a «needle in a haystack», or rather look for one byte among hundreds of others. The allocated period will narrow the search.
9. Be careful with pauses
When recording the CAN log, it may be necessary to stop recording in order to check the sensors, reconfigure the device or act on the indicator (add fuel or lower the tire pressure). You can use recording pauses for this. However, keep in mind that during subsequent decryption of the log, you may find spaces and gaps in records that could contain data you need.
For example, an indicator that changes every 7 seconds, and you paused at the sixth second. It means that the indicator was not recorded, it was lost.
Pauses in the recording can lead to data loss. Moreover, during the playback, the pause will also be maintained and the search may be complicated. Therefore, use pauses when recording as little as possible. A full and large recorded log is better than a short and useless log.
We hope that these tips will help you to use full CAN Scanner potential and create a complex solution for individual tasks.
However, if your project requires more in-depth knowledge, you have a chance to explore CAN Scanner capabilities at the practical course in the Russian office Galileosky.