National Instruments 653X Manuale Utente

© National Instruments Corporation

For example, if you specify a timebase of 100 kHz and a timebase divisor 
of 25, the resulting acquisition/generation rate would be 4 kHz. 
100 kHz/25 = 4 kHz.

If you are using a version of NI-DAQ prior to version 6.8, the minimum value for 

timebase divisor is 2.

In LabVIEW, you can specify the transfer rate directly using the Digital Clock 

Config VI (called by the DIO Start VI). The software will choose the closest transfer rate 
by selecting the frequency and divisor. To see the actual transfer rate, create an indicator at 
the actual clock frequency output of the Digital Clock Config VI.

By default, data transfer starts upon a software command (the Digital 
Buffer Control VI called by the DIO Start VI in LabVIEW and the 

DIG_Block_In

 and 

DIG_Block_Out

 functions in NI-DAQ C interface). 

However, you have the option of using a hardware trigger to start, stop, or 
start and stop data transfer.

The three types of trigger signals available are the start trigger, the stop 
trigger, or the start and stop trigger.

A start trigger is a trigger that initiates a pattern I/O upon receipt of a 
hardware trigger on the ACK (STARTTRIG) pin.

Starting Data Transfer Using a Trigger

When using a stop trigger, transfer starts upon a software command. Once 
a hardware trigger is received on the STOPTRIG pin, a predetermined 
amount of pretrigger and posttrigger data is saved in the buffer. Once this 

REQ

ACK (STARTTRIG)

Posttrigger Data