DWDT

[russ_ingram]

The one thing I am working on that I could use some assistance with is knowing the Digital Waveform file format. I can't find documentation on this format anywhere.

We are trying to get Serial Data Words to load into our NI-6561 in a reasonable amount of time. We are anticipating a thousand serial Data words at about 3K patterns each. Our existing method takes minutes to load, which is unacceptable. Using a "Read Waveforms from file.vi" (See Below) and feeding it all of the waveforms from one Digital waveform file (Could be a “DWDT Array Dlog” File) appears to be a promising solution. I have reverse engineered the format and have made it working model. It is a binary file. We need to know the real format of this file: what all the fields are, how long each one really is and if there are uses for what appear to be a null pad in the header. If I go with what I know we may find out down the line that we have problems based on our unknowns. Knowing the format can help us to be more secure when we build an outside tool to generate this file. So that our solution will actually work properly and that we can label each version of the file to assure conformance and maintainability.

[hfarley2]

Hi russ_ingram

Have you tried building your digital waveforms in the NI Digital Waveform Editor software (http://sine.ni.com/nips/cds/view/p/lang/en/nid/13050)? You can build them in this and then save them to file. Then as you mentioned in your post use the Read Waveforms from file.vi to feed in all the waveforms from that single file you create in the Digital Waveform editor. 

Regards,

hfar2

[russ_ingram]

Thanks for your response. The problem is not about using NI tools to build the digital (DWDT) format. We can do that and it is an easy thing to do. The problem is, the people that know how to build the waveforms will be using their tools to build, document, show to Configuration Management, work with the customer, and archive the waveforms. We have guessed at the format of the DWDT files and can generate working ones. We need to know the format so we can describe to the producers of the waveforms exactly what the format really is and document it. They need to make their tool convert these documented waveforms into a NI DWDT (currently unknown binary) format. This conversion needs to be proven to the customer that the translation of their waveforms to the NI DWDT format is absolutely correct. This translator tool needs to work on any file we give it throughout the future of this project. Not just happen to work with the early sample waveforms fall in the category of our guesstimate of the format of the file.

[hfarley2]

What tools will your other people be using to build the waveforms? I am currently looking to see if I can find anything that explains what you are looking for. It will likely be very difficult to build a single tool that can convert anything to the exactly the NI format but I will look and let you know if I can I find anything about the NI binary format.

Regards,

hfar2

[russ_ingram]

Again thanks for looking into this for us. The tools that are being used are either MatLab directly generating the DWDT or Excel with a VB script to generate the DWDT file. We are planning on using attributes to match the name of the waveform with the pattern along with several other pertinent pieces of information. Multiple patterns can be in each DWDT file. We are also hoping we can put information in the file header like the name of the file, revision, style of waveform, etc. Any software that is used to generate the waveforms will have to be validated.

[hfarley2]

Hi russ_ingram,

After talking with some of my colleagues here about your issue I was able to find a couple things that might be helful for you.

1. http://zone.ni.com/reference/en-XX/help/370592N-01/scopesfp/hws/ - The HWS file format is based on the HDF5 file format which appears to be a fairly common and widely used file format. Looking into that might help guide you in buidling this converter. 

2. http://www.ni.com/example/30169/en/ - here is an example which enables you to write and read HWS files in Visual Basic. This example appears to be a little old however I still wanted to pass it on to you just in case it is still helpful.

3. As a final option you could read the non HWS digital waveforms into LabVIEW based on their file format and then just use labVIEW to write an HWS file. This way you only have to directly deal with file formats you are familiar with. 

Regards, 

hfar2