HDLC/LAPB protocol testing

[Pierre Lambert]

I use Labview to spy and decode an HDLC/LAPB protocol on serial interface.
Does anybody have experience on protocol testing with Labview ?

Thanks

[Ben]

Hi Pierre,

I have done some. Do you have a specific question?

Ben

[Standardnutzer]

Hi folks,
does one of you have a HDLC encoder and decoder example? - Yes I need to do it in software.
Probably anyone has a fast c dll that will work in LabView?
Thanks for any answers...

Uli

[Ben]

The last time I worote anything serious involving HDLC, CPU's just were not fast enough to keep up with my expected throughput.

The de/encoding can be hadled with strategic type casting but the challenge is probably still going to be the "bit stuffing". For that part of the job I would review some of the LV Challenges for notes on how to handle the bit-wise operations quickly.

Do need to support ALL of HDLC or just a sub-set?

What could possibly mandate having to do this job in software?

Curious,

Ben

[Dennis_Knutson]

Here's something that might help you get started. We're creating some HDLC messages in software and using a custom board with an FPGA to actually transmit the frames to a product. It has not really been optimized in any way. We only need to send a few messages and the time it takes to do that is far overshadowed by the tests we're doing. I've removed all of the hardware specific code and you'll have to find a LabVIEW replacement for the CRC generation.

[Standardnutzer]

Ben and Dennis,

thanks to both of you for your rapid replies.

I will give you a short overview of my application. I do have a working one way transmitting system with PCs on both sides. The system itself is pretty complex and can not be replaced.
The system just transmits bits so I have to bring those bits in bytes that can be processed from the receiving PC.
Somehow I have to mark the beginning of a data packet or at least the beginning of a byte in this bit stream. For this I need any flag-sequence and of course I have to make sure that this sequence does not occur in the bit stream. HDLC is a common way to do that and I hoped that someone did it before. That's why I am asking for HDLC.

Ben:
I know that the whole thing would not be very fast in Matlab that was why I was thinking of using a C written dll.

Dennis:
I didn't try your code so far but I'll do so immediately.

Thanks again

Uli

[Ben]

OK Uli,

The ball is in your court. Let us know how the code offered by Dennis (Hi Dennis! long time not talk) works.

If you use a variation on such please take the time to post a representative sample of what you used to serve others like yourself in the future.

Ben

[zoran]

Uli,

here are two files for HDLC encoder and decoder. We are using it here at NASA and they work fine but you might have different algorithm for decoding so CRC will be different.

Zoran

[Omnipoint]

We downloaded the HDLC encoder and decoder from zoran, but it appears that there is a dll missing.  Does anyone have the dll or know how to get it?  Is zoran still around?

[zoran]

I am still around. All the files you need should be in that .zip file. Only one dll is needed and I put it in attachment just in case.

If you need anything more sent me an e-mail. My encoder/decoder works fine so don't worry.

Zoran