Measurement Computing TempBook rev.3.0 - Manual (Page 112)

10-16 Enhanced API Programming Models (TempBook) TempBook User’s Manual
Background Acquisition
This example reads scans from several channels into a user-allocated
buffer in the background. Functions used include:
•
VBdaqAdcArm&(handle&)
•
VBdaqAdcSetAcq&(handle&, DaamNShot&, 0, scans&)
•
VBdaqAdcSetFreq&(handle&, freq#)
•
VBdaqAdcSetMux&(handle&, 1, channels&, DgainX1&,
1)
•
VBdaqAdcSetTrig&(handle&, DatsSoftware&, 0,0,0,0)
•
VBdaqAdcSoftTrig&(handle&)
•
VBdaqAdcTransferGetStat&(handle&, active&,
retCount&)
•
VBdaqAdcTransferSetBuffer(handle&, buf%(),
scans&, DatmCycleOff& + DatmUpdateSingle&)
•
VBdaqAdcTransferStart(handle&)
•
VBdaqClose(handle&)
•
VBdaqOpen("TempBook0")
•
VBdaqSetErrorHandler(handle&, 100)
The constants used are defined as follows:
Const channels& = 8
Const scans& = 9
Const freq# = 200
As usual, the device is opened and the error handler set up:
handle& = VBdaqOpen("TempBook0")
ret& = VBdaqSetErrorHandler(handle&, 100)
On Error GoTo ErrorHandlerADC4
The acquisition is configured for 9 post-trigger scans and Nshot mode:
ret& = VBdaqAdcSetAcq&(handle&, DaamNShot&, 0,
scans&)
Set up the scan configuration for channels 1 to 9 with a gain of ×1:
ret& = VBdaqAdcSetMux&(handle&, 1, channels&,
DgainX1&, 1)
Set the post-trigger scan rates:
ret& = VBdaqAdcSetFreq&(handle&, freq#)
Set the trigger source to a software trigger command; the other trigger
parameters are not needed with a software trigger.
ret& = VBdaqAdcSetTrig&(handle&, DatsSoftware&,
0,0,0,0)
Arm the acquisition:
ret& = VBdaqAdcArm&(handle&)
Now to set up the buffer for a background acquisition in update-single
mode with cycle-mode off:
ret& = VBdaqAdcTransferSetBuffer(handle&, buf%(), scans&, DatmCycleOff& +
DatmUpdateSingle&)
Start the transfer, and trigger to begin transferring data:
ret& = VBdaqAdcTransferStart(handle&)
ret& = VBdaqAdcSoftTrig&(handle&)
These next few lines wait for the first data to be received, by checking the retCount value after calling
daqAdcTransferGetStat()
:
retCount& = 0
While retCount& = 0
ret& = VBdaqAdcTransferGetStat&(handle&, active&, retCount&)
Wend
With the same function, wait for the acquisition to complete:
While active& <> 0
ret& = VBdaqAdcTransferGetStat&(handle&, active&, retCount&)
Wend
Print "Acquisition complete:"; retCount&; "scans acquired."