Arthur,
According time difference between "$GPRMC..." & "$GPGGA..." displays on the screen, is it correct to say that it takes 156 ms to read in and display "$GPRMC" package?
Thanks

<2012.05.11 07:43:11.296>
$GPRMC,124311,A,4201.7977,N,09142.7227,W,000.0,352.2,110512,000.3,W*76#0D#0A
<2012.05.11 07:43:11.452>
$GPGGA,124311,4201.7977,N,09142.7227,W,1,09,1.0,249.0,M,-31.3,M,,*78#0D#0A
<2012.05.11 07:43:11.577>
$GPVTG,352.2,T,352.6,M,000.0,N,0000.0,K*7A#0D#0A

Arthur,
The screenshot is not from the log files. It's from the display on screen. Anyway, base on those screen display, is there anyway I can figure out how long it takes to read in packages starting with "$GPRMC". It's hard to figure that out by looking at the log. Since the time stamp is embedded within the package. Please refer to attached file for physical log file.
Thanks again.

Arthur,
Thanks for the reply.
The data I posted earlier is "before parsing".
Anyway, I took more samples with different modes of loggin - Before parsing, after parsing and after filtering. The time interval between "$GPRMC" & "$GPGGA" in those modes are pretty much the same.
Please refer to the attached screenshop. Base on these reading, what can I say about the time (roughly) it takes to read in $GPRMC?
Thanks for the help.

Write to log file before parsing

<2012.05.11 07:28:00.270>
$GPRMC,122800,A,4201.7854,N,09142.7238,W,000.0,004.0,110512,000.3,W*77#0D#0A
<2012.05.11 07:28:00.426>
$GPGGA,122800,4201.7854,N,09142.7238,W,1,07,1.4,253.8,M,-31.3,M,,*72#0D#0A
<2012.05.11 07:28:00.551>
$GPVTG,004.0,T,004.4,M,000.0,N,0000.0,K*7A#0D#0A
<2012.05.11 07:28:01.268>
$GPRMC,122801,A,4201.7855,N,09142.7238,W,000.0,004.0,110512,000.3,W*77#0D#0A
<2012.05.11 07:28:01.424>
$GPGGA,122801,4201.7855,N,09142.7238,W,1,07,1.4,253.8,M,-31.3,M,,*72#0D#0A
<2012.05.11 07:28:01.549>
$GPVTG,004.0,T,004.4,M,000.0,N,0000.0,K*7A#0D#0A
<2012.05.11 07:28:02.282>
$GPRMC,122802,A,4201.7856,N,09142.7238,W,000.0,004.0,110512,000.3,W*77#0D#0A
<2012.05.11 07:28:02.423>
$GPGGA,122802,4201.7856,N,09142.7238,W,1,07,1.4,253.8,M,-31.3,M,,*72#0D#0A
<2012.05.11 07:28:02.563>
$GPVTG,004.0,T,004.4,M,000.0,N,0000.0,K*7A#0D#0A
<2012.05.11 07:28:03.281>
$GPRMC,122803,A,4201.7856,N,09142.7238,W,000.0,004.0,110512,000.3,W*76#0D#0A
<2012.05.11 07:28:03.437>
$GPGGA,122803,4201.7856,N,09142.7238,W,1,07,1.4,253.8,M,-31.3,M,,*73#0D#0A
<2012.05.11 07:28:03.577>
$GPVTG,004.0,T,004.4,M,000.0,N,0000.0,K*7A#0D#0A


Write to log file after parsing

<2012.05.11 07:38:41.302>
$GPRMC,123841,A,4201.7855,N,09142.7205,W,000.0,169.1,110512,000.3,W*77#0D#0A
<2012.05.11 07:38:41.442>
$GPGGA,123841,4201.7855,N,09142.7205,W,1,09,1.4,246.6,M,-31.3,M,,*7D#0D#0A
<2012.05.11 07:38:41.582>
$GPVTG,169.1,T,169.4,M,000.0,N,0000.0,K*7B#0D#0A
<2012.05.11 07:38:42.300>
$GPRMC,123842,A,4201.7856,N,09142.7205,W,000.0,169.1,110512,000.3,W*77#0D#0A
<2012.05.11 07:38:42.456>
$GPGGA,123842,4201.7856,N,09142.7205,W,1,09,1.4,246.6,M,-31.3,M,,*7D#0D#0A
<2012.05.11 07:38:42.597>
$GPVTG,169.1,T,169.4,M,000.0,N,0000.0,K*7B#0D#0A
<2012.05.11 07:38:43.314>
$GPRMC,123843,A,4201.7856,N,09142.7205,W,000.0,169.1,110512,000.3,W*76#0D#0A
<2012.05.11 07:38:43.470>
$GPGGA,123843,4201.7856,N,09142.7205,W,1,09,1.4,246.6,M,-31.3,M,,*7C#0D#0A
<2012.05.11 07:38:43.595>
$GPVTG,169.1,T,169.4,M,000.0,N,0000.0,K*7B#0D#0A
<2012.05.11 07:38:44.297>
$GPRMC,123844,A,4201.7857,N,09142.7205,W,000.0,169.1,110512,000.3,W*70#0D#0A
<2012.05.11 07:38:44.453>
$GPGGA,123844,4201.7857,N,09142.7205,W,1,09,1.4,246.6,M,-31.3,M,,*7A#0D#0A
<2012.05.11 07:38:44.578>
$GPVTG,169.1,T,169.4,M,000.0,N,0000.0,K*7B#0D#0A
<2012.05.11 07:38:45.295>
$GPRMC,123845,A,4201.7857,N,09142.7205,W,000.0,169.1,110512,000.3,W*71#0D#0A
<2012.05.11 07:38:45.451>
$GPGGA,123845,4201.7857,N,09142.7205,W,1,09,1.4,246.5,M,-31.3,M,,*78#0D#0A
<2012.05.11 07:38:45.592>
$GPVTG,169.1,T,169.4,M,000.0,N,0000.0,K*7B#0D#0A


Write to log file after filtering

<2012.05.11 07:43:11.296>
$GPRMC,124311,A,4201.7977,N,09142.7227,W,000.0,352.2,110512,000.3,W*76#0D#0A
<2012.05.11 07:43:11.452>
$GPGGA,124311,4201.7977,N,09142.7227,W,1,09,1.0,249.0,M,-31.3,M,,*78#0D#0A
<2012.05.11 07:43:11.577>
$GPVTG,352.2,T,352.6,M,000.0,N,0000.0,K*7A#0D#0A
<2012.05.11 07:43:12.294>
$GPRMC,124312,A,4201.7977,N,09142.7227,W,000.0,352.2,110512,000.3,W*75#0D#0A
<2012.05.11 07:43:12.450>
$GPGGA,124312,4201.7977,N,09142.7227,W,1,09,1.0,249.0,M,-31.3,M,,*7B#0D#0A
<2012.05.11 07:43:12.575>
$GPVTG,352.2,T,352.6,M,000.0,N,0000.0,K*7A#0D#0A
<2012.05.11 07:43:13.309>
$GPRMC,124313,A,4201.7977,N,09142.7227,W,000.0,352.2,110512,000.3,W*74#0D#0A
<2012.05.11 07:43:13.449>
$GPGGA,124313,4201.7977,N,09142.7227,W,1,09,1.0,249.0,M,-31.3,M,,*7A#0D#0A
<2012.05.11 07:43:13.589>
$GPVTG,352.2,T,352.6,M,000.0,N,0000.0,K*7A#0D#0A
<2012.05.11 07:43:14.307>
$GPRMC,124314,A,4201.7977,N,09142.7227,W,000.0,352.2,110512,000.3,W*73#0D#0A
<2012.05.11 07:43:14.447>
$GPGGA,124314,4201.7977,N,09142.7227,W,1,09,1.0,249.0,M,-31.3,M,,*7D#0D#0A
<2012.05.11 07:43:14.588>
$GPVTG,352.2,T,352.6,M,000.0,N,0000.0,K*7A#0D#0A
<2012.05.11 07:43:15.290>
$GPRMC,124315,A,4201.7977,N,09142.7227,W,000.0,352.2,110512,000.3,W*72#0D#0A
<2012.05.11 07:43:15.446>
$GPGGA,124315,4201.7977,N,09142.7227,W,1,09,1.0,249.0,M,-31.3,M,,*7C#0D#0A
<2012.05.11 07:43:15.586>
$GPVTG,352.2,T,352.6,M,000.0,N,0000.0,K*7A#0D#0A
<2012.05.11 07:43:16.319>
$GPRMC,124316,A,4201.7977,N,09142.7227,W,000.0,352.2,110512,000.3,W*71#0D#0A
<2012.05.11 07:43:16.475>
$GPGGA,124316,4201.7977,N,09142.7227,W,1,10,1.0,248.9,M,-31.3,M,,*7F#0D#0A
<2012.05.11 07:43:16.600>
$GPVTG,352.2,T,352.6,M,000.0,N,0000.0,K*7A#0D#0A

Based on the time stamps of the below attached log, the time difference between the 1st GPRMC & GPGGA is 156 ms. Is it correct to say that it takes the Serial Data Logger 156 ms to serially read in the GPRMC message? These two messages come out back to back, only seperated by CR/LF characters.
Thanks

<2012.05.10 08:14:43.369>
$GPRMC,131443,A,4201.8115,N,09142.7195,W,000.0,190.5,100512,000.3,W*71#0D#0A
<2012.05.10 08:14:43.525>
$GPGGA,131443,4201.8115,N,09142.7195,W,1,09,1.3,240.4,M,-31.3,M,,*7B#0D#0A
<2012.05.10 08:14:43.665>
$GPVTG,190.5,T,190.9,M,000.0,N,0000.0,K*72#0D#0A
<2012.05.10 08:14:44.383>
$GPRMC,131444,A,4201.8116,N,09142.7195,W,000.0,190.5,100512,000.3,W*75#0D#0A
<2012.05.10 08:14:44.539>
$GPGGA,131444,4201.8116,N,09142.7195,W,1,09,1.3,240.4,M,-31.3,M,,*7F#0D#0A
<2012.05.10 08:14:44.664>
$GPVTG,190.5,T,190.9,M,000.0,N,0000.0,K*72#0D#0A
<2012.05.10 08:14:45.381>
$GPRMC,131445,A,4201.8116,N,09142.7195,W,000.0,190.5,100512,000.3,W*74#0D#0A
<2012.05.10 08:14:45.537>
$GPGGA,131445,4201.8116,N,09142.7195,W,1,09,1.3,240.4,M,-31.3,M,,*7E#0D#0A
<2012.05.10 08:14:45.662>
$GPVTG,190.5,T,190.9,M,000.0,N,0000.0,K*72#0D#0A
<2012.05.10 08:14:46.380>
$GPRMC,131446,A,4201.8116,N,09142.7195,W,000.0,190.5,100512,000.3,W*77#0D#0A
<2012.05.10 08:14:46.536>
$GPGGA,131446,4201.8116,N,09142.7195,W,1,09,1.3,240.4,M,-31.3,M,,*7D#0D#0A
<2012.05.10 08:14:46.661>
$GPVTG,190.5,T,190.9,M,000.0,N,0000.0,K*72#0D#0A
<2012.05.10 08:14:47.378>
$GPRMC,131447,A,4201.8117,N,09142.7195,W,000.0,190.5,100512,000.3,W*77#0D#0A
<2012.05.10 08:14:47.519>
$GPGGA,131447,4201.8117,N,09142.7195,W,1,09,1.3,240.4,M,-31.3,M,,*7D#0D#0A
<2012.05.10 08:14:47.659>
$GPVTG,190.5,T,190.9,M,000.0,N,0000.0,K*72#0D#0A
<2012.05.10 08:14:48.377>

Arthur,
Thanks for the quick response.
I saw the timestamp displayed. But my main question is as follows:
. Timestamp starts when the 1st byte/bit data received or at the end of block.
I already have the log activated, but the timestamp is embedded within the data block, not same as displayed. Please refer to my attachment in the original message.
Thanks again

I am looking for a Serial Data monitor software for use in our lab. I came across the free copy of your Advanced Serial Port Monitor software. It appears to meet what we need. However, there are a couple of issues, I am hoping that you can provide me with the answers.
1. I am trying to capture the GPS NMEA sentences from a GPS receiver via RS-232. Before each of the GPS NMEA sentences, there is a time stamp associated with it. Is the time stamp displayed when first bit/byte of the sentence being captured/logged? Or is the time stamp displayed when the CR/LF of each sentence is received?
2. How can I capture the time stamp and data just as it is displayed on screen? Currently, the time stamp in the log file is kind of embedded within the data in the log, and it does not seem to match up with time stamp in the display. How can I configure the "Log File" option to  capture time stamp/data just as being displayed?
tks