Checksum Error

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robert_s
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Checksum Error

Post by robert_s » Mon Dec 27, 2004 12:19 pm

We are getting checksum error when downloading from PowerSet and SDR33. What are the possible reason which cause this error, and how serious is this error for the integrity of downloaded data? Could we just ignore it?

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Darcy Detlor
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Post by Darcy Detlor » Mon Dec 27, 2004 4:07 pm

Hello,

Are you downloading a Powerset or an SDR33?

Do you always get a checksum error when downloading the SDR or only with certain jobs? Does it make any difference between machines?

I recall that the checksum error on the Sokkia download is computed by adding up all the characters sent and then checking them using a formula defined in the Sokkia transfer documentation.

Unfortunately the error could be caused by a single bit changing in a single character. Depending upon the error it could effect any of angle, distance, number or description.

A checksum error is not something that should be ignored, because it is telling you that the computed sum does not match the sum that is included in the transfer.

I would do the minimum to try to resolve the problem:

1. Set up the SDR to do a nice printed report and dump that to the computer so you can examine the raw data carefully. Do a visual inspection with the raw data printed from MicroSurvey.

2. Dump the coordinates from the SDR into MicroSurvey and then reprocess the raw file. If the downloaded coordinates do not match the computations done by reprocessing the raw file then the point protection will jump out and identify a difference between the two.

3. I'll bet that another forum member has experienced something like this and has other suggestions to add to this.
Darcy Detlor,
President,
MicroSurvey Software Inc.
darcy.detlor@microsurvey.com

robert_s
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Post by robert_s » Sat Apr 16, 2005 1:08 pm

Regarding source code which handles download/upload with Sokkia. Is it written in-house by MicroSurvey development team, or is it provided in form of a library from Sokkia?

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Darcy Detlor
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Post by Darcy Detlor » Sat Apr 16, 2005 4:56 pm

The upload / download program is written by MicroSurvey (and it was written quite a few years ago) based upon the written documentation provided by Sokkia. The checksum formula is very simple.
Darcy Detlor,
President,
MicroSurvey Software Inc.
darcy.detlor@microsurvey.com

rwhatman
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Post by rwhatman » Mon Apr 18, 2005 9:15 am

Checksum may not be a big problem.

You will be missing one or more letters from the last Description.

I have the field PLUG the Sokkia into the wall.

The batter of the Sokkia my be the problem. When it gets low in power the Checksum error can happen.

Also we run into it downloading to are Server sometimes.

We always download two ways for a backup.

Hope some of these ideas help.

surveyor6925
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Location: Norwalk, Ohio

Post by surveyor6925 » Mon Apr 18, 2005 1:13 pm

Used to have an SDR 33. Did the same thing. Never seemed to affect the data.

robert_s
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Post by robert_s » Mon Apr 18, 2005 3:47 pm

I think there is a number of reasons and therefore it is difficult to debug. Initially I susspected not sufficient battery power and dirty cable sockets. However, today I tested Sokkia ProLink and It worked flowlessly while MicroSurvey was giving me the error on the same battery and cables. I compared the downloaded files with "File Difference" utility and there are errors, maybe not significant this time but I would prefer not to have them. I still think battery and cables are the factors, but ProLink is coded somewhat differently and is more rebust. I have to mention I'm using MicroSurvey CAD 2002, if any changes have been made to the download code in CAD 2004 please let me know.

Glen Cameron
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Checksum

Post by Glen Cameron » Wed Apr 20, 2005 7:55 am

One thing to ensure, make sure that MSCAD is receiving data before you start sending on the SDR. If you start sending too soon, sometimes the first character or two (or more) will not be received by our program.

Cheers,
Glen W. Cameron, C.E.T.
City of North Bay, Ontario

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