Streaming data from another PC, combining it with DAQ measurement

[MRH]

Hi

I'm just getting back into LabVIEW after 2 years without using any NI software, so apologise if I'm missing something really obvious and this is a simple question. I have had a search of the forums, but can't find what I'm looking for. Perhaps I just don't know what to look for.

I'm starting to plan a combined data acquisition system for an engineering test, which will involve two PCs. I would like some advice on how to set up a LabVIEW system on one of them.

I need to produce a system which will:
(a) log measurement data using normal DAQmx method - that bit should be straightforward enough.
(b) import independent measurement data from the other PC, probably via an Ethernet LAN. What’s a good way to get data into LabVIEW?
(c) correlate the 2 sets of data. What I really want to do is feed the input data into my measurement system in real time.
(d) produce data files incorporating all data

I'm not involved in programming the system for the other PC, but can have some input into how it’s arranged.
 
Is TCP the best way to go? I would be very grateful for any guidance anyone can offer on how to do steps (b) and (c).

Thanks.

[Ben]

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MRH wrote:

Hi

I'm just getting back into LabVIEW after 2 years without using any NI software, so apologise if I'm missing something really obvious and this is a simple question. I have had a search of the forums, but can't find what I'm looking for. Perhaps I just don't know what to look for.

I'm starting to plan a combined data acquisition system for an engineering test, which will involve two PCs. I would like some advice on how to set up a LabVIEW system on one of them.

I need to produce a system which will:
(a) log measurement data using normal DAQmx method - that bit should be straightforward enough.
(b) import independent measurement data from the other PC, probably via an Ethernet LAN. What’s a good way to get data into LabVIEW?
(c) correlate the 2 sets of data. What I really want to do is feed the input data into my measurement system in real time.
(d) produce data files incorporating all data

I'm not involved in programming the system for the other PC, but can have some input into how it’s arranged.
 
Is TCP the best way to go? I would be very grateful for any guidance anyone can offer on how to do steps (b) and (c).

Thanks.

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You will have to give us more info about the dat on the other machine for us to be able to help.

Is the data on a web-page (DataSocket reads)

In a DAQ sub-system on the other machine (Action Engine Served to the clinet via VI server)

In a file on the other machine (map the drive and file read)

In memory on the other machine (SCRAMNet)

So tell us more about the data.

Ben

[MRH]

Data would be written to a file on the other PC in one form or other. I could request certain file type

That’s part of my question I suppose, any advice on what’s the best format to enable fast data transfer, to correspond with my measurement data in real time?

[Ben]

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MRH wrote:
Data would be written to a file on the other PC in one form or other. I could request certain file type

That’s part of my question I suppose, any advice on what’s the best format to enable fast data transfer, to correspond with my measurement data in real time?

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Real-Time describes a system that is bounded in time (Deterministic) and there is nothing deterministic about file operations.

I am not going to be able to wlak you thruogh this completely but I can outline one extreme and let other propose more practicle solutions.

SCRAMNet is reflective memory that links shared memory in multiple machines via a dedicated fiber link. Data trasfers are meassure in femto-seconds or there-abouts. SCRAMNet ships with examples to allow you to do file transfers between machines.  SCRAMNet is costly! If you include a smart switch and redundanat paths, two nodes could cost about $50K to set-up.

Similar connection can be done using Ethernet and TCP/IP. You could set-up a listner on your end and tell the other app to to send the updates via TCP/IP.

Re: format...

I'd look at what I have coming from the local DAQ and then specify what ever I thought would make my life easy.

Just giving you some ideas that you can smack down in the process of defining your requirements,

Ben

[MRH]

Ben, thanks for your replies.

I'm not a programmer at heart, just a scientist dabbling with LabVIEW, so sorry for daft questions.

Based on your answers, I now understand the SCRAMNet option is too extreme and expensive (but thanks for explaning what it does), and TCP is likely to be the most practical way forward.

I'll try to work with TCP connection then, which requires me to go away and have a think and do some tests.

I may return to this thread when I hit an inevitable problem, but thanks for pointing me in the right directon.