Providing Context For Decoding When Frame Information Is Missing

There may be times when you need to provide information to the analyzer because the context for decoding a frame is missing. For example, if the analyzer captured a response frame, but did not capture the command frame indicating the command.

The analyzer provides a way for you to supply the context for any frame, provided the decoder supports it. (The decoder writer has to include support for this feature in the decoder, so not all decoders support it.  Note that not all decoders require this feature.)

If the decoder supports user-provided context, three items are active on the Options menu of the Control window and the Frame Display window. These items are Set Initial Decoder Parameters, Automatically Request Missing Decoding Information, and Set Subsequent Decoder Parameters.  (These items are not present if no decoder is loaded that supports this feature.)

Set Initial Decoder Parameters is used to provide required information to decoders that is not context dependent but instead tends to be system options for the protocol.

Choose Set Initial Decoder Parameters in order to provide initial context to the analyzer for a decoder. A dialog appears that shows the data for which you can provide information.

If you need to change this information for a particular frame :

  1. Right-click on the frame in the Frame Display window
  2. Choose Provide <context name>.

Alternatively, you can choose Set Subsequent Decoder Parameter from the Options menu.

  1. This option brings up a dialog showing all the places where context data was overridden.
  2. If you know that information is missing, you can't provide it, and you don't want to see dialogs asking for it, un-check Automatically Request Missing Decoding Information.
  3. When unchecked, the analyzer doesn't bother you with dialogs asking for frame information that you don't have. In this situation, the analyzer decodes each frame until it cannot go further and then simply stop decoding.