User`s manual

CYDAS UDR Library User’s Guide CYDAS UDR Library Description and Use

The Windows library contains four functions for managing these Windows global memory buffers:

 cbWinBufAlloc()

 cbWinBufFree()

 cbWinArrayToBuf()

 cbWinBufToArray()

Real-time acquisition under Windows

Real-time acquisition is available for Windows. To operate at full speed in Windows, the A/D board must

have an onboard FIFO buffer. All of our advanced designs have FIFO buffers, including our CYDAS xP

boards (except for the CYDAS 8P), and many of our ISA boards, such as the CYDAS 80x, CYDAS 160x,

CYDAS 140x, and CYDAS 1802ST. All of these data acquisition boards will operate at full speed in

Windows.

Applying software calibration factors in real time on a per-sample basis eats up machine cycles. If your CPU

is slow, or if processing time is at a premium, withhold calibration until after the acquisition run is complete.

Turning off real-time software calibration saves CPU time during a high speed acquisition run.

Processor speed

Processor speed remains a factor for DMA transfers and for real-time software calibration. Processors of less

than a 150 megahertz (MHz) Pentium class may impose speed limits below the capability of the board (refer

to specific board information.)

If your processor is less than a 150 MHz Pentium and you need an acquisition speed in excess of 200 kilohertz

(

kHz), use the NOCALIBRATEDATA option to a turn off real-time software calibration and save CPU time.

After the acquisition is run, calibrate the data with

cbACalibrateData().

Visual Basic for Windows

To use the CYDAS UDR Library with Visual Basic, include the CYDAS UDR Library declaration file

CBW.BAS in your program. Include the file as a module in the project, or include it by reference inside those

Forms which call into the CYDAS UDR Library. Once the declarations for the CYDAS UDR Library have

been added to your project, call the library functions from any Form's event handlers.

When using the 32-bit version of Visual Basic, CBW.BAS references CBW32.DLL to call CYDAS UDR

Library functions. This is accomplished with conditional compile statements. When using 16-bit versions of

the Visual Basic (such as versions 3.0 or older), these conditional compile statements must be deleted.

For Visual Basic 6.0 and older, Windows memory buffers cannot be mapped onto arrays. As a consequence,

the

cbWinArrayToBuf() and cbWinBufToArray() functions must be used to copy data between arrays and

Windows buffers.

Example:

Count = 100

MemHandle = cbWinBufAlloc (Count)

cbAInScan (......,MemHandle,...)

cbWinBufToArray (MemHandle, DataArray(0), 0, Count)

For i = 0 To Count

Print DataArray(i)

Next i

cbWinBufFree (MemHandle)