DAQ from a Rohde & Swartz (handheld) spectrum analyzer using Labview

[Izum27]

The device I am working with is a Garmin eTrex Legend GPS receiver. I have it set to text out and I can use Hyperterminal to see the text that it is outputting. I want to use Labview to write that data to a Labview measurement file. Would this example (I don't need to write to the device) allow me to to do that since it outputs, they say ascii code or some sort of text string? Also what if I need to change to a different COMx port do i just change ASRLx::INSTR everywhere I see it?

-Andrew
Thank you for your help

[Izum27]

I am getting the same error that I have been getting. It is giving me this error: Error - 1073807202 occurred at Property Node in VISA Configure Serial Port (Instr).vi

I ran the same code you gave me and it gave me the same error. I don't know whats going on.

-Andrew

[Izum27]

Another question .... why is there not a VISA open function? I noticed this earlier and added one to see if that was the problem but then it gave me the same error and said it was at the VISA open in the same SubVI.

[JohnM 64]

That is a fairly common question about the property node.  It turns out that if you use a VISA Property Node on a VISA Resource Name that is not already open, it automatically performas a VISA Open function for you.  So, even though the error is occurring at the property node, it is still having trouble opening the VISA Resource.

I saw that JLS recommended earlier to try a simple program that only opened and closed the VISA Resource that you wanted to use and see if the same error occurred.  Did you ever perform that test?  If we can't even get the resource open, there is no need to try out a large, involved program.  If you've already done this and posted it earlier... sorry for asking again.  It's hard to sort through these long posts sometimes!  Let us know if you can even open the resource, and we'll go from there.

-john m

[Izum27]

This is the test that I ran to see if I could just use the VISA open, read, and close and I set my system COM2 to the proper settings to match my GPS receiver. Do I have to add any extra VISA software or something? It just keeps giving me errors and the VISA open and VISA read.

- Andrew

[Emilie S.]

Hi Andrew:

Looks like you need to uninstall and reinstall VISA.  Please reference the knowledgebase on how to resolve VISA error -1073807202.

Regards,

Emilie S.

[Izum27]

That fixed it!!!!!!!!!!!!!!!!!!! Thank You very much my Vi's work now. I told people that error but I guess they didn't realize.

Now a second question. The string from what I understand from this website, http://www.gpsinformation.org/dale/interface.htm,  -see text mode, is 55 characters long. I ran the VI and it returned 8 characters back. I noticed that it is reading 8 bits so is it true that each character is represented by 1 bit? If so is there a way to collect certain ranges of string? Like for instance I would like the Latitude information which is characters 15 through 21 and the longitude information which are characters 23 through 30. If that is too difficult then I would like to have chracters 14 through 30. I can live with that.

Thank You
Andrew

[Emilie S.]

Hi Andrew:

One ASCII character is one byte or 8 bits.  If  you are reading in 8 characters then you are getting 64 bits.  I don't know a lot about your device but in looking at the site you listed it seems that you are not getting all of the characters you should be getting.  What part of that long string does it look like you receive, time, position, or velocity?

To answer your question though, yes you can just get portions of a string, or in otherwords parse your data.  Have a look at the string palette.  There is a function called String Subset that I think will work for you.

Regards,

Emilie S. 

[Izum27]

The part of the string that I am getting is @0507251 which is the opening character and then the 2 digits for the year, two digits for the month, two digits for the day of the month, then it starts to give the first digit for the hour for time but it should give the whole time and then not give the position becuase I'm indoors. In hyperterminal I will get the whole date and time and a stright line for position. I'm testing it now to see if I get the same results.

I put a while loop around the read fuction and realized that the display is only displaying 64 bits at a time. Can I change this so that it can display the whole bits which is about. Also I will try the string subset and get back to you.

Thank You

Andrew

[Izum27]

I tried that String Subset but I'm not getting nething when I try to display it. I think its because the string is only displaying 8 characters and when I choose to have the 15th character then I guess Labview is not seeing that. I know I asked this already but can I have the whole string displayed which is about 50 characters (all displayed at one time)?

Thank You
-Andrew

I attached the GPS read VI just incase I did it wrong.