High speed data logger VI

[Blore]

I have two questions regarding the high speed data logging VIs available at the following link

http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3EE4756A4E034080020E74861&p_node=DZ52303&p_submitted=N&p_rank=&p_answer=&p_source=External

1) When we retrieve the data is it in decompressed form and do we get back the original resolution?

2) Is it possible to use the VIs with 4472 card? If not can somebody make it compatible with 4472?

Regards,
Mondeep

[Jeremy_L]

Hi Mondeep,

In response to your second question, the 4472 card is NOT supported by the VIs found on the linked webpage.

The 4472 running at full speed on all 8 channels generates approximately 3.2 MB/s. HSDL generally increases throughput from standard DAQ and LV disk tools by about 30%, so you can see some difference. Also, there is not much documentation on it. So, if you are not aching for the extra 30% of bandwidth, I would recommend looking at this simple logging example for the 4472 instead. However, if you really need that extra bandwidth because of channel count or speed, le
t me know and I can provide you with the VIs that take advantage of this.

As for your first question, I am unclear as to which data your are referring to. Are you referring to data output from performing a high speed data read, a data file, or from the DSA card? Thanks!

Jeremy L.
National Instruments

[Jeremy_L]

Sorry for the broken message!

In addition, most computers are able to stream to disk at about 20 MB/s. So it should be able to write and handle the output of the 4472 just fine, without needing the HSDL.

Jeremy L.
National Instruments

[Blore]

Dear Jeremy,
Thanks for the response. Yes,We do require the extra bandwidth as channel count is high as well as there is considerable online calculation and display in the application. We found one of the bottle neck is the logging speed. If you can send the VIs you are talking about it would be great.

In my first question what I was asking was HSDL VIs has the provision to compress the data before logging i.e it can convert 16bit data to 12 bit data. But when we read back the data from the logged file can we get the 16bit resolution back from the logged 12bit data.
If yes, how it is acheived?

Regards
Mondeep

[Jeremy_L]

Hi Mondeep,

For the 4472, there is a 32->24 bit lossless mode and a 32->16 bit lossy mode. On 16 bit MIO, there is a 16 bit no compression mode and an 8 bit lossy mode. For 12 bit MIO, there is a 16->12 but lossless mode and and an 8 bit lossy mode.

Unfortunately, we do not support the HSDL VIs that I had talked previously about, and so I am unable to post them here. I apologize for this inconvenience.

Hope this answers all of your questions! Let me know if you need anything else!

Jeremy L.
National Instruments