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

[JohnM 64]

Hi Izum,

I looked at your code, and I believe I see why you are only getting 8 characters each read.  You have the value of 8 wired into the "data bits" input of the configure serial port VI, which is correct, because each byte of data has 8 bits.  However, you also have this input of 8 wired into the byte count input of the VISA Read.  This input tells the read how many bytes, or characters in this case, to read in.  If you want more characters read, simply create a separate input for this byte count, and put in however many characters/bytes you want to read!

Hope this helps!

john

[Izum27]

Yes! That helped, but why is it when I connect the output of the string subset to a Labview Measurement file it gives me an error saying that I have connected two different terminals. I would like this information to go to a Labview Measurement file. How would I do that? Am I connecting the wrong wires?

-Andrew

[JohnM 64]

The LVM VI is expecting a numeric data type, not a string.  You are reading in a number, but it is currently in a string format.  You can use the string to number conversion functions (found in the String palette under String/Number conversions) to change this string into a number (a blue or orange wire represents a number, a pink thick wire represents a string).  You can then wire this numeric data type into the LVM VI.

john

[Izum27]

Question ... I am reading an instruemnt and I am getting a value that I want, but I would like to read teh instrument again and get another value so that I can find the average because the value is always changing a little. Is it possible to save a value for a little while so that I can get another value so that I can do some arithmetic to it?

-Andrew

[Emilie S.]

Hi Andrew:

One solution may be to build an array.  If you are using a while loop you can use shift registers to build an array and therefore save "old" data.  I have included a small example that I threw together than may help you out, and better explain what I mean.

Emilie S.