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How to read Trace information?



Hello all,

Can someone explain how to read the TRCFMT messages?
For example,
15:54:18:230 : PACKET   : TRCFMT=  4;512 ;E; R;F<cr><lf><lf><cr>
15:54:18:230 : PACKET   : R=]<09><00><80><09><80><1F><F1><01><FF>/<01><E1><F1><00><0F><1F><00><F0><F0><0F><00>
15:54:18:230 : PACKET   : <FF><00><E0><E0><F0><0F><FE><0F><00><FF><esc><9E><0F><F1><00><F0><1F><10><F0><F0>
15:54:18:230 : PACKET   : <1F><10><1F><01><10><00><esc><91><esc><9C>0<00><E3><01><F1><F2><0F><01><00><F2><01>
15:54:18:230 : PACKET   : <1F><00><01><00><10><01><00><01><F1><01><00><F1><00><esc><91><F1><01><F1><00><F2>
15:54:18:230 : PACKET   : <01><00><00><02><E1><10><00><esc><91><0F><esc><91><00><01><10><01><F0><esc><91><0F>
15:54:18:230 : PACKET   : <FF><esc><91><FF><C0><FF><FF><EE><0F><EE><00><F0><F0><esc><91><00><01><F1><1F><00>
15:54:18:230 : PACKET   : <10><01><0F><10><01><0F><00><00><F0><1F><0E><F1><10><E2><00><1F><10><F1><F1><0E><10>
15:54:18:230 : PACKET   : <00><01><F1><0F><10><01><F1><00><01><FF><esc><91><0F><10><00><10><F1><00><00> <F2>
15:54:18:230 : PACKET   : <FF><1F><01><E1><00><F1><FF><00><E0><F0><F0><00><EE><E1><esc><91><C1><01>.<F0>!<E0>
15:54:18:230 : PACKET   : <F1><esc><91><0F><F1><02><1F><E0><esc><91><F2><01><E1><1F><1F><esc><91><F1><FF><esc>
15:54:18:230 : PACKET   : <91><01><00><E3><F0><00><02><F0><01><00><0F><1F><02><F1><01><FF><esc><91><E0><10>
15:54:18:230 : PACKET   : <1F><1F><10><F1><F1><F0><00><0F><esc><91><esc><9E><10><F0><0F><esc><91><F0><00><F1>
15:54:18:230 : PACKET   : <F0><10><F1><01><F0><01><F0><00>/<01><0F><10><F0><01><F0><10><01><1F><0F><10><00>
15:54:18:230 : PACKET   : <esc><91><0F><00><00><10><10><00><esc><91><E0><esc><91><0F><00><cr><lf><cr><lf><lf>

What should this data tell me, except that this is a trace for the right lens?


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Are you the device asking for trace data, and receiving this? Because in this case I'd really recommend, during initialization, to ask for trace if format "1" (ASCII absolute), instead of "4" (Packed binary). This would be both a lot more readable (or, well, just plain readable) for you personally, as well as easier to code for (assuming you're using a language with something that has basic text/string processing capabilities).

As for what this tells you, first, the TRCFMT line, tells you (besides that it's for the right lens):

1. That data (i.e. radius distances in the R records in this case) will be in the packed binary format (hardest to read/use, really no reason to do that if you don't have to, or need to be able to work with extremely low bandwidth or memory).

2. That you will get 512 radius distances in the R records (main data of the frame traces. Each value is radius distance from the center position of the frame).

3. That the angular distance between the R values are equal, so the total 360° will be spread equally, effectively giving you a radius over a sequence with about 0.7° rotation between them.

4. That the frame trace you're receiving is from tracing a frame, rather than a demo value or a pattern. (probably not actively useful for you beyond basic verification you're not receiving something unexpected)

And, of course, the R record, which has the actual shape of the frame trace, as a sequence of the radius distance from the center along the circumference of the frame shape.

Your main issue with reading this is, again, that "4" Packed Binary format, which is not particularly human readable. You can see the details of the format in the DCS, section (in 3.14 ver03) "Packed binary format". Though, really, read all of 5.4 "Tracing Datasets" , for a cover on how to read frame trace data.

The main records you care about are TRCFMT and R. Good idea to also look at A for when the angle distances aren't "E"/equiangular but "U" (rare but happens) or "C" (so far very very rare). Depending on what your device is/does, it's possible you don't care about sag data ZFMT/Z/ZA at all, otherwise behavior is generally similar to the main trace data.

Notice that if you're not reading files with pre-made trace data (in which case what it has is what you get), but are instead asking a VCA Host for the frame trace, then you can on initialization specify which formats you want/support. Most modern LMS will probably be able to convert/interpolate whatever format trace they have to whatever you asked for.

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