SICK LMS-200 and reflectivity data mode.

Have you worked with a SICK rangefinder? Have you used it to get reflectivity data from its scans? If so, please read this!
My lab has a SICK LMS200-30106. The manual states in section 4.1.7 that we should be able to change the operating mode of the scanner to include reflectivity data (using the BM_TGM telegram and mode 0x2B). It also states that responses are formatted as described in 4.2.46 (MWREM_TGM telegram, code 0xF5)--in short, two bytes give the distance value for that angle and another 2 bytes give the reflectivity.
I can successfully set the SICK to return MWREM_TGM packets, but they all look something like this (Hope the formatting turns out ok):
2 80 de 2 f5 1 0 1 0 b5 0 b5 40 <^--header bytes--------------------^> ad 1b 0 0 ac 1b 0 0 <snip...> a9 8 0 0 a0 8 0 0 10 d2 6 <^-start scan data ..........................end scan---^ chksum^>
...basically, the data portion of the scan gives 181 angle measurements (as I expected) where in each case the second 2 bytes of each angle measurement (the reflectivity portion) is zero. I get scans like this no matter what I do--I've put retroreflective strips, shiny metal, whatever--the reflectivity bytes are ALWAYS zero.
So am I doing something wrong? Am I mis-reading the MWREM_TGM packet format? Something else? Any help is much appreciated. Thanks,
Ed Clarkson Georgia Tech Mobile Robot Lab
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Edward Clarkson wrote:

......
Never done it the way you describe, but have managed to use 77H (LMSKFGDEF_TGM) and mode 1 or 3 to get reflector information (more or less TRUE/FALSE [REFLECTOR/NO_REFLECTOR]) together with normal range measurement. Works well with 3M Diamond Grade.
Out of interest, what are you trying to achieve?
Regards
Sjur
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I've heard of this 'low-resolution' mode but have never heard details-- thanks, I'll look into that. There've been a number of groups to use the SICKs for reflector barcode readings on mobile robots, and I think that's how most of them do that. Unfortunately, I don't think that will do much good for what we'd like to do...

The simple answer is that my advisor asked me to :). More informatively--we'd like to see if we can use reflectivity information for terrain characterization (on a mobile robotics platform). Obviously, on/off isn't useful for that but a ~13,000 value gradient (as the SICK manual describes) might be. Thanks,
Ed
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