I'm developing an OBD2 scan tool with the help of a hardware OBD2 simulator. I'm getting an inconsistency between the DTC returned by 0202xx (xx being the number of the freeze frame) and 03 / 07 / 0A.
How do the Freeze Frame DTCs correlate with the stored / pending / permanent DTCs. From the specifications I assumed the Freeze Frame DTCs are a subset of the stored /pending / permanent ones. With the hardware simulator though it looks as they're completely independent — meaning they come from a different memory in the ECU(s).
Can someone clarify this?
Further consulting of SAE1979.2002 indicates that in this case it looks like my OBD2 simulator behaves erratic, as the standard requires that the DTC for which freeze frames are available are stored as well.