Communication to device using RS-232 to USB Converter

[wolfgang2021]

I am using a RS-232 to USB converter to connect my set of GK & GFK Scales to the computer. How do I get the device to read out into LabVIEW? All of the examples I have seen have a *IDN\r in them that is sent to the device via the VISA Write command, what does *IDN\r mean and why when I run an example vi with my device I get nothing back from it? The part number for the RS-232 to USB Converter is 778473-04, could  it be that this particular model is not compatable with LabVIEW?

[wolfgang2021]

I have attached a separate gauge to the USB Converted and I can get a read out from it, but it comes out in funny symbols. How would I convert these sybols into number?

There is a picture of this attacted here.

[Albert.Geven]

This data is probably binay (not ASCII) and where in the manual did you find that it responds to *IDN.

This is a normal command for SCPI commandset instruments but not all instruments are SCPI.

[wolfgang2021]

Thnaks for the information.

About the *IDN, nowhere in the manual did it mention that I was just wondering what that command did, its everywhere on this website on all of their examples.

How would I go about translating the binary into readable numbers. The program I am using is very simple, all it is just a VISA serial command wired to a VISA write wired to a VISA read wired to a VISA close wired to a simple error handler.

[Dennis_Knutson]

The manual for the instrument should explain the format of the data. You have not attached it.

[wolfgang2021]

Here is the manual for the gauge, sorry I didn't post it earlier.

[Dennis_Knutson]

You have a bit of work. First, you will have to synch your read. The device is coonstantly sending and you will need to read a variable amount of bytes until the first byte is the length, the second is the page, and byte 8 is the correct check sum. After that, you read a constant 9 bytes. Use the string to byte array function then the Index Array to get bytes 4 and 5. The Join Numbers function will create a single U16 and that gets converted per the formula (minus the multiplication by 256) on page 32.

[wolfgang2021]

Here is a picture of the program so far, is it wired correctely, and how do we plug in the (hi,lo) number into the formula on page 32 for mbar?

and what do I need to put in for the VISA write?

Thanks

[Dennis_Knutson]

Not at all correct. You don't put anything at all in a VISA Write, you have to first synch to the data being transmitted, yoy do not wire the number of bytes wriiten/read to anything, aafter synching, you need to wire constants to the index array function, and then you just have to wire the joined number to the divide function and the output of that to a subtract function.

[wolfgang2021]

Where does this part of the formula (high byte x 250 + low byte) happen? Does this happen in the Join Numbers function? You mentioned in an earlier post that i wasn't able to do the multiplication, "(minus the multiplication by 256) on page 32."