How to parse UDP byte stream ?

[TobiasF]

Hello,

 I receive binary sensor data from different sensors via UDP (Header + Data (e.g. 4 byte uint) + End). I can read the data as a string (I used the UDP Receiver.vi example), but what is an efficient way to parse the data und to view the data on an indicator ?

cheers, Tobias

[GerdW]

Hi Tobias,

when the data string has a fixed length it should be easiest to TypeCast into a properly defined cluster!

[TobiasF]

Hi,

thank you for the fast answer. Unfortunately the message size is not fixed, but the size is contained in the header (byte 3), which has a fixed size. how can i parse this ?

Regards, Tobias

[TobiasF]

Solved 🙂

[joe5213]

Hi, I am new to Labview and am trying to do exactly this. Would it be possible to you to generate a simple example of "TypeCast into a properly defined cluster"? Thanks Joe

[crossrulz]

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@joe5213 wrote:

Hi, I am new to Labview and am trying to do exactly this. Would it be possible to you to generate a simple example of "TypeCast into a properly defined cluster"? Thanks Joe

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The second Type Cast is the example you are looking for.  The first one was just to make some the string in the first place.

[joe5213]

Hello, I have used the example UDP Receive.vi to read UPD packets from another computer. I have wired the output of the UDP Read into a String to Byte Array to verify that I am receiving the correct UPD data words. The UDP data is the same for every packet. I've read in another post that because the data length is the same then it would be simple to use TypeCasting. I am having trouble and need some help. I have created my Cluster and it has the order of the data that is in the packet. Some words are 14-bits wide and other are of various bit-width. Can anyone help me get the TypeCasting to work? The problem is when I try to connect the Cluster to the TypeCast's type input.

Thank you very much,

joe

[RavensFan]

Do you actually have a 14-bit wide word?  If so, you have a very abnormal data structure.  Most words are 16 bits wide.  And when you say others are various widths, exactly what widths?

There is no way we can help you solve your typecasting unless you attach a sample of the data string you receive, what the results should be, and also some description of the protocol that decodes it into different values.  If you truly have data elements that are bit-packed in a way such as a 14-bit word, then typecasting won't help you and you'll have to parse it down to a bit level to piece together all the data.  If you do have data elements that consist of one or more whole bytes, then typecast probably will work.

But as I said in the other thread, you should really start your own new thread rather than tacking on to a six year old thread.

[joe5213]

Thanks. I will look a the data widths again and also post a new post.

joe