Measurement Computing WaveBook rev.3.0 - Manual (Page 189)

WaveBook User’s Manual, 6-22-99 daqX API - Programming Models C-15
Data Packing & Rotating
This section demonstrates an acquisition made up of pre-trigger and post-
trigger scans from multiple channels using a DSP-based analog trigger. It
also uses data packing and rotating. Functions used include:
•
VBdaqAdcArm&(handle&)
•
VBdaqAdcSetAcq&(handle&, DaamNShot&, 0, scans&)
•
VBdaqAdcSetFreq&(handle&, POST_freq!)
•
VBdaqAdcSetRawDataFormat(handle&, DadfPacked&)
•
VBdaqAdcSetScan&(handle&, chans&(), gains&(),
polarities&(), channels&)
•
VBdaqAdcSetTrig&(handle&, DatsHardwareAnalog&,
rising&, level%, HYSTERESIS%, chans&(0))
•
VBdaqAdcSoftTrig&(handle&)
•
VBdaqAdcTransferGetStat&(handle&, active&, retCount&)
•
VBdaqAdcTransferSetBuffer(handle&, buf%(), BLOCK&,
DatmCycleOff& + DatmUpdateSingle&)
•
VBdaqAdcTransferStart(handle&)
•
VBdaqClose(handle&)
•
VBdaqCvtRawDataFormat&(buf%(), DacaUnpack, retCount&,
BLOCK&, channels&)
•
VBdaqOpen("WaveBook0")
•
VBdaqSetErrorHandler(handle&, 100)
•
VBdaqWaitForEvent(handle&, DteAdcData&)
These declarations specify the number of channels, the pre- and post-scan
counts and frequencies, and block size for the acquisition:
Const channels& = 4
Const PRE_SCANS& = 5
Const POST_SCANS& = 9
Const PRE_freq! = 100#
Const POST_freq! = 200#
Const BLOCK& = (PRE_SCANS& + POST_SCANS&)
Also declared are the trigger level, hysteresis, and rising parameters:
Const level% = 0
Const HYSTERESIS% = 0
Const rising& = 0
daqAdcSetRawDataFormat
daqAdcArm
daqAdcSetAcq
daqAdcTransferSetBuffer
daqAdcSetFreq
daqAdcSoftTrig
daqAdcSetTrig
daqWaitForEvent
daqAdcSetScan
daqAdcTransferStart
daqAdcTransferGetStat
daqAdcCvtRawDataFormat
No Has all data
been collected?
Yes
The buffer is dimensioned, as well as arrays to hold values for channels, gains, and polarities:
Dim buf%(BLOCK& * channels&)
Dim chans&(channels&), gains&(channels&), polarities&(channels&)
Initialize the arrays with the channel numbers and gains for each channel:
chans&(0) = 1 ' channel numbers
chans&(1) = 3
chans&(2) = 5
chans&(3) = 7
For i& = 0 To channels& - 1
gains&(i&) = DgainX1& ' unity gain
polarities&(i&) = 1 ' bipolar
Next i&
Now to open the device and set up the error handler:
handle& = VBdaqOpen("WaveBook0")
ret& = VBdaqSetErrorHandler(handle&, 100)
On Error GoTo ErrorHandlerADC6
Specify the packed-data format for the transfer:
ret& = VBdaqAdcSetRawDataFormat(handle&, DadfPacked&)
Configure the acquisition for Nshot, with 9 post-trigger scans:
ret& = VBdaqAdcSetAcq&(handle&, DaamNShot&, 0, scans&)
Set the scan configuration using the arrays initialized earlier:
ret& = VBdaqAdcSetScan&(handle&, chans&(), gains&(), polarities&(),
channels&)