This seems to be the character string that the 6540 logger reports:
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The APRS streaming data logger compiles a character string consisting of
the following:
ASCII character “@”,
The date and time on a 24 hour clock in the following format: Day of
Month, Hour, Minute, where each value is a 2 digit number.
Lower case “z”,
Latitude/longitude “position” string: 4903.50N/07201.75W_.
Scalar average wind direction (in degrees) over one minute
(reported as 000 if the average wind speed is zero);
Forward slash “/”,
Sustained one-minute wind speed (in mph);
Lower case “g”,
Gust (peak wind speed in mph in the last 5 minutes);
Lower case “t”,
Temperature (in degrees Fahrenheit). Temperatures below zero are
expressed as -01 to -99;
Lower case “r”,
Rainfall (in hundredths of an inch) in the last hour,
Lower case “p”,
Rainfall (in hundredths of an inch) in the last 24 hours,
Upper case “P”,
Rainfall (in hundredths of an inch) since midnight,
Lower case “h”,
Humidity (in %. 00 = 100%), omitted if missing;
Lower case “b”,
Barometric pressure (in tenths of millibars/tenths of hPa), omitted if
missing;
The letter “L”, (upper case if solar radiation is below 1000, lower
case if solar radiation is between 1000 and 1999), omitted if
missing,
Solar Radiation (in watts per square meter) last 3 digits (see above),
omitted if missing,
The following character string inside the quotes (including the
leading period): “.DsVP“. This will indicate that a Davis Vantage
Pro is sending the APRS data packet with its own proprietary
device.
Carriage Return character
Line Feed character
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I think you'll find that the LOOP data from the standard 6510 loggers is a blind alley - this is not a text string, but a binary packet. Unless you've got some processing in place to transcode the binary packet into a meaningful text string (which presumably you need for the APRS modem) I can't see how it would be useful
