Checksum calculation without white space character about marnav HOT 6 CLOSED

Thanks for the insight. I do not know what the standard says, I do not have it, nor have I seen it.
Found the information about ALR here: https://www.cruisersforum.com/forums/f134/opencpn-and-external-nmea0183-alarms-81396.html
According to the examples provided there, it seems the alarm description can contain whitespaces.

Interpreting your screenshots, the device delivers

$AIALR,00000.00,026,A,V,AIS: no position sensor in use*5D

but nmeatool prints

$AIALR,00000.00,026,A,V,AIS:nopositionsensorinuse*5D

and claims the checksum is wrong? Yes, this clearly seems wrong.
Thanks for finding the bug!

from marnav.

You're sure you're screenshots are accurate?

I try to reproduce and do:

echo "\$AIALR,00000.00,026,A,V,AIS: no position sensor in use*5D" | ./nmeatool

I get

$AIALR,00000.00,026,A,V,AIS: no position sensor in use*5D
        error: checksum error: checksum error (actual:6D, expected:5D)

There seems to be an issue with checksum, but I do not get your result.
Also your nmeatool output seems to strip the whitespaces, which I cannot reproduce.

Various sources (quickly found by your favorite search engine), examples:

• https://alekunderwater.github.io/nmea0183_checksum_calculator.html
• https://code.activestate.com/recipes/576789-nmea-sentence-checksum/

do not seem to treat whitespaces in a special way.

To me, it actually looks like $AIALR,00000.00,026,A,V,AIS: no position sensor in use*5D is wrong
and should be $AIALR,00000.00,026,A,V,AIS: no position sensor in use*6D".

Cannot reproduce, does not look like a bug to me.

from marnav.

I 'm sure. You missed the one zero in the sentence after AIALR. There are six zero chars. The array that is seen in the picture is
AIALR,000000.00,026,A,V,AIS: no position sensor in use

Also, I fixed the bug in my local code by getting

raw_ <= 31.

from marnav.

You're right, I missed a 0. Then I try again:

echo "\$AIALR,000000.00,026,A,V,AIS: no position sensor in use*5D" | ./nmeatool

yields the output:

$AIALR,000000.00,026,A,V,AIS: no position sensor in use*5D
        Name  : Set Alarm State
        Talker: Mobile AIS station
        Time UTC                       : 00:00:00
        Alarm Number                   : 26
        Alarm Condition                : Threshold Exceeded
        Alarm Acknowledge              : Not Acknowledged
        Alarm Text                     : AIS: no position sensor in use

Still does not match the output you presented with allegedly wrong checksum and spaces removed in the output of nmeatool.

As for the nmea_reader.cpp, this really looks like ignoring spaces and does not work for ALR. Will fix this, thanks!

from marnav.

See b91e74c, nmea_reader.cpp processes now spaces as well.

from marnav.

I did not try to use with nmeatool with string input. Rather I used it with reading serial data. There may be a difference with input style. Anyway issue is closed. Thank you.

from marnav.