National Instruments Welding System 321645c-01 사용자 설명서

Chapter 2

Function Reference — SCAN_Start

NI-DAQ FRM for PC Compatibles

2-314

National Instruments Corporation

If you have selected external start triggering of the data acquisition operation, a high-to-low
edge at the STARTTRIG* I/O connector input on the MIO-16/16D, or the EXTTRIG*
connector on the MIO-F-5/16X initiates the data acquisition operation after the

SCAN_Start

call is complete. Otherwise,

SCAN_Start

issues a software trigger to initiate the data

acquisition operation before returning.

Note

If your application calls

DAQ_Start

SCAN_Start

, always ensure that you

call

DAQ_Clear

before your application terminates and returns control to the

operating system. Unless you make this call (either directly, or indirectly through

DAQ_Check

DAQ_DB_Transfer

), unpredictable behavior can result.

You must use the

SCAN_Setup

and

SCAN_Start

functions as a pair. Making a single call to

SCAN_Setup

with multiple calls to

SCAN_Start

will fail and return error noSetupError.

If you have an SC-2040 connected to your DAQ device, NI-DAQ will ignore the
sampTimebase and sampInterval parameters. NI-DAQ automatically supplies these
parameters to optimally match your hardware.

If you select sampTimebase = 0 and scanTimebase = 0, you must use the same source for
both. This requirement is enforced on most MIO devices through hardware because you
connect both timebases to the SOURCE5 I/O connector pin. On E Series devices, if you use
the

Select_Signal

function to specify the source of an external sample and external scan

timebase, you must specify the same source for both timebases.