DaqPad 6070E SCXI 1100 and 1303

[ColinBrown]

Hi,

I'm attempting to measure the temperature in a k type thermocouple connected to a SCXI 1100 via an SCXI 1303. This system is connected to a DaqPad 6070E. I cannot create a daqmx channel. I believe this is because I must use traditional ni-daq legacy with the 6070E. I don't understand how I use this in Labview to gather the data that I am recording. Any ideas/tips?

Best regards,

Colin Brown

[hannahW]

Hello Colin,

You are correct in saying that the 6070E is supported in Traditional DAQ only, the latest version of this is 7.4.1

I'm not sure which version of LabVIEW you are using, but if you navigate to the help menu within LabVIEW and then select 'Find Examples' or 'Example Finder'

This will bring up the example finder, where you can find lots of pre-built examples demonstrating many common concepts for LabVIEW programmers. In here I found an example called 'SCXI-1100 Thermocouple.vi' (this was located under 'Hardware Input and Output>>Traditional DAQ>>SCXI'

You will need to change the settings on the front panel of this example to map to your channels in MAX that you have set up for this device and the SCXI modules. 

This example should get you started with seeing how to use the Traditional DAQ API and get you acquiring data straight away.

I hope this helps, if you have any questions let me know

Hannah

NIUK & Ireland

[ColinBrown]

Many thanks,

It works. I can't seem to get my head around how it works though. Would there be any disadvantages in creating each channel as a traditional ni-daq virtual channel and then gathering the data.  At the minute I only want to record one channel, but will move onto three.

[ColinBrown]

I guess a better way of saying that would be:

1) I have created three virtual channels, all through the scxi module (using its cjc source)
2) I then acquire, display and store the data using ai congig.vi etc.

Is this a reasonable method?

And can anyone offer me some information on buffer sizes/values? I know nothing about them.

Thanks

[devchander]

Hi,

In brief, The buffer size input parameter on AI Config determines the size of the memory buffer that you want to use during the data acquisition. Then what you have to do is allocate suitable number of number of scans to read on the AI read.

for example, during continous acq,if your buffer size is 1000,  scans to read is 100 and sampling rate selected is 1000 samples/sec

Your AI read in a while loop will run 10 times in a secont to retrieve 1000 sapples /sec.

since the buffer is cyclic, The trick here is to always read out the bufer values befor the next set of values overwrite it.

for keep scans to read always less than or equal to buffer size. also keep track of scan back log from the AI read

It specifies the amount of data remaining in the buffer after AI read.If scan backlog increases steadily, you are not reading data fast enough to keep up with the acquisition, and your newly acquired data may overwrite unread data and give you an overwrite error. To correct, decrease the scan rate, increase the number of sacns to read, read the scans more often, or increase the Buffer size.

This atached VI should give you an idea on how to build a vi for buffered acq.

Hope this helps.

Regards

Dev