Header size in high speed data logger

[george-195]

Hallo,
How to recognize size of the header in data file written by high speed data logger in LabView 5.1.
Seems this value strongly determines all values read further from the file.
Any help appreciated,
George

[Dennis_Knutson]

Have you looked at the corresponding 'High Speed Data Reader' example or the subVI 'create binary header'? The header length is the first thing written to the file and in the reader example, it's the first thing read so that the header can be stripped.

[george-195]

Thank you for reply.
I am very new to LabView and want record data with it and anlyze elsewhere (Origin can deal with it). Honestly do not know how to extract it from the diagram...
George

[Dennis_Knutson]

The reader VI gets the first 4 bytes. This is type cast to an integer and then the header is read. I have no experience with origin so I can't say how you would set that up there.

[george-195]

Thanks,
The beginning of the data file is (in HEX):
00 00 01 40 00 00 00 10 46 54 2C 20 41 32 2C 20 ....
How to extract the number then? Sorry, my knowledge of binary is poor...
George

[Dennis_Knutson]

0000 0140 is the first four bytes and 0140 hex is the same as 320 decimal (0x1 + 4x16 + 1x256).

[george-195]

Thank you Dennis,
This what I have found in the meantime, but Origin Import wwizard shows 320 bytes is too low - maybe it needs more since DataLogger writes here I32 number...
George

[Dennis_Knutson]

If the file was actually created by the high speed data writer VI and if a header was actually written to the file, the first bytes are the header size, which defines the size of the header. You should be ignoring the first 324 bytes. Don't forget the endian problem with LabVIEW data. You will have to do a byte swap.

Since you have LabVIEW, why don't you just try to run the High Speed Data Reader. If the data comes in correctly there, then you have something set wrong in your other program.

[george-195]

Yes, this was what I did. Data Reader works fine giving results in portions to the screen.
While importing to Origin I am asked for the header size, then below is an offset and header variables. I did not define any apart channels, what offset means here - do not recognize. Big-Endian filed is marked.
Then it asks to create Pattern - which in the case (i suppose) has 4 columns of integer type, size 2-byte numbers and 'count' - given as 1 each time as then I am able to see 4 columns of data as numbers. I think as I16 these should be -32768 to 32767, or ?
DAQ is PCI-MIO16E-1 with 12 bit resolution.
Oooops,great thanks for your help, but answer please this as well.
George

[Dennis_Knutson]

The high speed data logger saves each scan as a 2D array of I16 numbers.