Measurement Computing TempBook rev.3.0 - Manual (Page 73)

TempBook User’s Manual tbkCommand Reference (Standard API) 9-13
tbkRdNForePreT
DLL Function int tbkRdNForePreT(uint *buf, uint count, uint *retcount, uchar *active);
C tbkRdNForePreT(unsigned int _far *buf, unsigned int count, unsigned int _far
*retcount, unsigned char _far *active);
QuickBASIC BtbkRdNForePreT% (buf%, ByVal count%, retcount%, active%)
Visual Basic VBtbkRdNForePreT% (buf%(), count%, retcount%, active%)
Turbo Pascal tbkRdNForePreT( buf:WordP; count:word; retcount: WordP; active:ByteP
):integer;
Parameters
uint *buf An array where the A/D samples will be placed
uint count The number of scans to be taken
Valid values: 1 - 32767
uint *retcount Pointer to an integer representing the number of scans actually taken
uchar *active Pointer to a flag indicating whether or not the pre-trigger acquisition is still active
Returns TerrFIFOFull - Buffer overrun
TerrNoError - No error
See Also tbkSetTrigPreT, tbkSetTag, tbkRdNForePreTWait, tbkRdNBackPreT
Program References PRETEX1 (all languages)
tbkRdNForePreT reads multiple A/D scans, initiated by the tbkSetTrigPreT command, in
the foreground. Unlike the tbkRdNBackPreT command, this function does not use interrupts and
does not return control immediately to the application program. It will only return when either the
specified count has been satisfied or the acquisition completes.
This function may be called subsequent to configuring a pre-trigger acquisition using the
tbkSetTrigPreT
command. Once this command has been called, it will return only when one of
two possible conditions are met: 1) The specified number of scans has been collected, or, 2) the
trigger has been detected and the acquisition has completed. In the latter case, the returned 'active'
flag will be 0 and the number of scans actually collected will be returned in 'retcount'.
Note: If the A/D converter has not been configured to acquire data, this function may wait
indefinitely, hanging the computer.