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Updated help files for several screens.

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Collin Kidder
2023-02-13 22:02:47 -05:00
parent ba2d3c221f
commit 5ef8403d40
9 changed files with 97 additions and 46 deletions
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help/framedetails.md
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@@ -16,6 +16,10 @@ If you have a DBC file loaded which matches the ID you've selected then you will
The top right graph is a histogram of all the bits and the number of times each bit was set. This can be used to quickly visually see where data has changed.
The bottom right graph is of each individual byte as its value varies over time. All textual information can be saved to a text file for later analysis.
The bottom right has 8 graphs, one for each possible byte in a standard CAN frame (CAN-FD support is coming... eventually) Double clicking one of these graphs will size it up and remove the other 7 graphs. Double clicking again brings the 8 byte view back.
The interval histogram is in logarithmic scale and shows a listing of what intervals were seen between frames. This can be used to visually see the frame timing. Some frames get sent very regularly. They will show a very pronouced bell curve. Other frames might get sent on demand. These frames will have peaks at odd places and not conform to a nice distribution. For instance, in the picture you can see that the frame shows many frames around 15-20ms timing but some around 40, 60, and 80 as well. This might indicate the frame is not always sent or it might show that the frame is getting lost. After all, those timings are all around multiples of 20ms.
As in other windows, it is possible to use the mouse wheel to scale all the graphs on this form and it is also possible to pan around by clicking and dragging. Selecting one axis will also let you scale / pan just that one axis.
In the middle there is a bitfield view. This is color coded based upon how often each bit changes. It is called the "heatmap" for this reason. Bits that don't change often are cold and colored blue. Bits that are hot get increasingly red. In the picture you can see distinct areas where the bits are blue, light blue, green, orange. This is highly indicative of a counter. When a counter is found you will find that the lower bit changes basically every frame, the next bit up every other frame, the next bit every fourth frame, etc. This produces a very distinct pattern in the heatmap. Bits that never change are black. This view thus allows one to see where changing data is found within a frame. Chances are you can ignore all the black parts and focus only on places where some change has happened.
The interval histogram is in logarithmic scale and shows a listing of what intervals were seen between frames. This can be used to visually see the frame timing. Some frames get sent very regularly. They will show a very pronouced bell curve. Other frames might get sent on demand. These frames will have peaks at odd places and not conform to a nice distribution. For instance, in the picture you can see that the frame shows quite a few messages around 100ms but messages extend out to around 600ms as well. Still, the logrithmic scale means that the faster interval is, by far, the most common.