Measurement-computing UL for NI LabVIEW Instrukcja Użytkownika Pobierz pdf (Strona 89)

Universal Library Virtual Instruments (VIs) Memory board VIs

Memory board VIs

MemRdPrt.VI

Reads pre-trigger data from a memory board that has been collected with either APretrBg.VI or APretrFg.VI

and arranges the data in the correct order (pre-trigger data first, then post-trigger data). This VI can only be

used to retrieve data that has been collected by either APretrBg.VI or APretrFg.VI with the ExtMemory

option set to TRUE. After each APretrFg.VI or APretrBg.VI call, all data must be unloaded from the memory

board with this VI. If any more data is sent to the memory board then the pre-trigger data will be lost.

Summary:

Inputs: BoardNum [U32] - The board number assigned when installed with InstaCal. Can

be 0 to 100.

FirstPoint [I32] - Index of first point to read or FROMHERE.

Count [U32] - Number of points (words) to read.

Outputs:

DataArray [U16] - Output data array.

ErrCode [I32] - Error code. See ErrMsg.VI.

Arguments:

BoardNum The board number associated with a board when it was installed with InstaCal.

FirstPoint Use the FirstPoint argument to specify the first point to be read. For example, to

read points #200 - #250, set

FirstPoint=200 and Count=50.

If you are going to read a large amount of data from the board in small chunks then

set

FirstPoint to FROMHERE (-1) to read each successive chunk. Using

FROMHERE (-1) speeds up the operation of MemRdPrt.VI when working with

large amounts of data.

Count Number of points (words) to read.

DataArray Data read from memory board.

ErrCode Error code returned from the Universal Library. Zero if no error occurred. Use the

ErrMsg VI to convert

ErrCode into a readable string.

Notes:

DT Connect conflicts - The .MemRdPrt.VI can not be called while a DT Connect transfer is in progress. For

example, if you start collecting A/D data to the memory board in the background (by calling AInScBg.VI or

AInScFg.VI with the

DTCONNECT + BACKGROUND options), you can not call MemRdPrt.VI until the AInScBg.VI

or AInScFg.VI has completed. If you do, you will get a

DTACTIVE error.

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Measurement-computing UL for NI LabVIEW Instrukcja Użytkownika Strona 89