LabVIEW
Reading from CO2 sensor connected to the PC
Solved!
Hi DP,
I have attached the error I am getting when I connect the string from VISA Read to the Scan From String and run the VI.
This error has NOTHING to do with your chart - why do you think so?
It's an error in the ScanFromString function and it has been discussed before.
Did you follow all the suggestion you got so far?
What is the string you want to parse? Which string content does enforce this error message? Why do you receive this string content?
Why is there no error handling after ScanFromString?
Please read your whole thread and follow all those suggestion you got!
Hi DP,
it seems (as I can tell from your image, where important parts are hidden) you STILL try to parse the very first line of your string, which does NOT suit to your format string!
The first line just reads "number z number" while you scan for "Z number z number"!
You have been told NOT to collect all data in a big string by concatenating - but you still do!
You have been told to get rid of the very first line in the string - but you still don't follow this advice!
I repeat:
Read the whole thread and follow the suggestions given to you!
When I run just the part of your code where it takes the string and feeds it through the scan from string, and I type in what I see on your Repsonse indicator, your code runs just fine for me. See the image below.
One question I have is that you are writing the command "*IDN?" which is the kind of thing you send to a device to query it for identifcation information, but you are getting back your Z data. Does that seem correct?
Are there other things coming into that response string that we can't see. Try displaying that response string with \codes display.
On your previous front panel screen shot, you had Enable Termination character turned off. Why did you do that? I think that is why you got multiple lines in one message. This time you enabled the termination character and got a single line. How fast is this device sending data? Is it sending one line of data every time you send the *IDN? command?
@DP123 wrote:The reason why I disabled the termination character was just to see what difference it would make. Not any really good reason 🙂
The termination character allows the VISA Read to stop when that character is read. Since your data always ends with a 0x0D0A combination, you really want the termination character to be turned on and with the 0xA as the termination character.
@DP123 wrote:The command IDN was already in the example in labview and that is why I just left it there. I actually did not know what it did until you just explained it. So what should I replace it with?
Since it looks like your instrument just sends you data at a periodic rate, I would just get rid of the writing part.
Something you should probably do is add a read before your loop. You can just throw that data away. The point of this read is to remove any partial messages and synch up to the start of the messages.
One more thing I just noticed: your messages start with a space as well. So you need to add a space before that Z in your format string.
