User`s manual

CYDAS UDR Library User’s Guide Analog Input Boards - PCYDAS 8
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PCYDAS 8
Analog Input
Analog input functions and methods supported
UDR:
cbAIn(), cbAInScan(), cbATrig(), cbFileAInScan()
UDR for .NET AIn(), AInScan(), ATrig(), FileAInScan()
Analog input argument values
Options BACKGROUND, CONTINUOUS, EXTCLOCK, CONVERTDATA, SINGLEIO, NOTODINTS,
EXTTRIGGER, NOCALIBRATEDATA
HighChan
0 to 7
Rate 25000 max. For other restrictions, refer to the PCYDAS 8 User's Manual
Range This board does not have programmable gain so the Range argument to analog
input functions is ignored.
Digital I/O
Digital I/O functions and methods supported
UDR:
cbDIn(), cbDOut(), cbDBitIn(), cbDBitOut()
UDR for .NET:
DIn(), DOut(), DBitIn(), DBitOut()
Digital I/O argument values
PortNum AUXPORT
DataValue
0 to 7
BitNum 0 to 2
Hardware considerations
Pacing analog input
Internal or external clock
Maximizing sampling rates
When paced by the onboard clock, the rate is set by an onboard oscillator running at 25 kHz. The oscillator
output may be divided by 2, 4 or 8, resulting in rates of 12.5 kHz, 6.25 kHz or 3.13 kHz. When pacing a single
channel from the onboard clock, these are the four choices of rate available. When a rate is requested within
the range of 3000 to 25000, the library selects the closest of the four available rates.
Scanning more than one channel divides the rate requested among the number of channels requested. The
maximum rate when scanning eight channels is 3130 (25000 divided by eight channels).
Although the PCYDAS 8 is capable of 25 kHz analog to digital conversions, not all computers in all
configurations can transfer the converted samples fast enough to sustain a 25 kHz sample and transfer rate
without missing some samples. This is especially true in the windows environment. Unfortunately, there isn't
much you can do to improve sampling rates in windows, but in DOS, where you have more control over the
process, you may be able to attain the full 25 kHz sampling rate.