Measurement Computing Data Acquisition Systems rev.10.4 - Manual (Page 22)

The program will then collect one sample of channels 0 through 7 using the VBdaqAdcRdScan function.
ret& = VBdaqAdcRdScan&(handle&,0, 7, buf%(), DgainX1&,
DafAnalog&+DafUnipolar&)
Print “Results of AdcRdscan:”
For x& = 0 To 7
Print Format$“& # & ####”; “Channel:”; buf%(x); “Data:”; buf%(x)
Next x&: Print
Counted Acquisitions Using Linear Buffers
This section sets up an acquisition that
collects post-trigger A/D scans. This
particular example demonstrates the setting
up and collection of a fixed-length A/D
acquisition in a linear buffer.
First, the acquisition is configured by
setting up the channel scan group
configuration, the acquisition frequency,
the acquisition trigger and the acquisition
mode. When configured, the acquisition is
then armed by calling the
daqAdcArm
function.
At this point, the Daq device trigger is
armed and A/D acquisition will begin upon
trigger detection. If the trigger source has
been configured to be
DatsImmediate& ,
A/D data collection will begin
immediately.
This example will retrieve 10 samples from
channels 0 through 7, triggered
immediately with a 1000 Hz sampling
frequency and unity gain. Functions used
include:
•
VBdaqAdcSetMux&(handle&, startChan&, endChan&, gain&, flags&)
•
VBdaqAdcSetFreq&(handle&,freq!)
•
VBdaqAdcSetTrig&(handle&, triggerSource&, rising&, level%,
hysteresis%,channel&)
•
VBdaqAdcSetAcq&(handle&,mode&,preTrigCount&,postTrigCount&)
•
VBdaqAdcTransferSetBuffer&(handle&,buf%(), scanCount&, transferMask&)
•
VBdaqAdcTransferStart&(handle&)
•
VBdaqAdcWaitForEvent&(handle&,daqEvent&)
This program will initialize the Daq device hardware, then take readings from the analog input channels in
the base unit (not the expansion cards). The functions used in this program are of a lower level than those
used in the previous section and provide more flexibility.
Dim buf%(80), handle&, ret&, flags&
The following function defines the channel scan group. The function specifies a channel scan group from
channel 0 through 7 with all channels being analog unipolar input channels with a gain of ×1. Specifying
this configuration uses
DgainX1 in the gain parameter and the DafAnalog and the DafUnipolar values
in the flags parameter. The flags parameter is a bit-mask field in which each bit specifies the
characteristics of the specified channel(s). In this case, the DafAnalog and the DafUnipolar values are
added together to form the appropriate bit mask for the specified flags parameter.
ret& = VBdaqAdcSetMux&(handle&,0, 7, DgainX1&, DafAnalog&+DafUnipolar&)
2-12 API Programming, General Models 988594 Programmer’s Manual