Hello,
I have an SR620 that i am trying to get some more life out of. I have
dedicated a raspberry pi 2 to recode data and make the files available through
the network. I wrote a small c deamond that will setup the counter to make
frequency measurements and save the result to a file on the flash card.
Overall it is basically working but.... on start up i have an odd behavior.
My file format is a "two column " file, column 1 is elapsed system time in
seconds, and column 2 is the measurement returned by the counter. When the
program starts I get 2 to 5 measurements that are wrong. A number of
measurement are returned in the first second,
How I setup the counter:
// get id of counter, if it is not an sr620, exit with error;
fprintf(stream,"*RST\n"); // system reset
sleep(10);
fprintf(stream,"CLCK 1\n"); // external timebase
fprintf(stream,"AUTM 0\n"); // automatic masurment off
fprintf(stream,"MODE 3\n"); // mesure freqency
fprintf(stream,"GATE1 E1\n"); // set for 10 second gate
fprintf(stream,"SIZE 1\n"); // 1 sample per mesurment
fprintf(stream,"TERM 1, 0\n"); // 50 ohm termination for
channel "A"
fprintf(stream,"LEVL 1, 0\n"); // trigger level 0.00
fprintf(stream,"TCPL 1, 1\n"); // AC coupling, channel A
sleep(4);
// pause for a bit
loop until quite {
fprintf(stream,"STRT;*WAI;XAVG?\n"); // start
measurement, wait till complete,
while ((bytesread = getline(from serial port stream) !=
-1) { // will block until full line
if (bytesread >10) break;
}
// write data to file,
}
// close serial port
// close data file
example output:
#type=Freq
#start_date=1482003092
#f_nom=2e+7
0, 1.999999881895E+07
0, 1.999999881912E+07
0, 1.999999881757E+07
7, 1.999999881856E+07
17, 1.999999881878E+07
27, 1.999999881900E+07
37, 1.999999881877E+07
47, 1.999999881908E+07
57, 1.999999881921E+07
What do you think?
Link
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