User`s manual

CYDAS UDR Library User’s Guide Analog Input Boards - UMDAS 0802 Series
78
Event notification
Even notification functions and methods supported
UDR:
cbEnableEvent(), cbDisableEvent()
UDR for .NET:
EnableEvent(), DisableEvent()
Event types:
ON_SCAN_ERROR (analog input), ON_DATA_AVAILABLE, ON_END_OF_AI_SCAN
The UMDAS 0802 also supports
ON_END_OF_AO_SCAN and ON_SCAN_ERROR (analog
output)
Hardware considerations
Acquisition Rate
When using the UMDAS 0802, most systems can sustain rates of 40 kS/s aggregate in
BLOCKIO mode, and 1
kS/s aggregate in
SINGLEIO mode.
BURSTIO (UMDAS 0802L)
BURSTIO mode allows higher sampling rates for sample counts up to the size of the FIFO. The UMDAS
0802L FIFO holds 4096 samples. Data is collected into the device's local FIFO. Data transfers to the PC don't
occur until the scan completes. For
BACKGROUND scans, the Count and Index returned by cbGetStatus() and
GetStatus() remain 0, and Status=RUNNING until the scan finishes. The Count and Index are not updated
until the scan is completed. When the scan is complete and the data is retrieved,
cbGetStatus() and
GetStatus() are updated to the current Count and Index, and Status = IDLE.
The UMDAS 0802L uses
BURSTIO as the default mode for non-CONTINUOUS fast scans with sample counts up
to the size of the FIFO (4096 samples).
BURSTIO mode allows higher sampling rates for sample counts up to
the size of the FIFO. Maximum
Rate values of non-BURSTIO scans are limited (see Rate on page 75). To
avoid the
BURSTIO default, specify BLOCKIO mode.
EXTCLOCK (UMDAS 0802)
By default, the SYNC pin is configured for pacer output and provides the internal pacer A/D clock signal. To
configure the pin for pacer input, use the
EXTCLOCK option.
If you use the
EXTCLOCK option, make sure that you disconnect from the external clock source when you test
or calibrate the device with InstaCal, as the SYNC pin drives the output.
Resolution
When configured for single-ended mode, the resolution of the data is 11 bits (data values between 0 and
2047). However, the CYDAS UDR Library maps this data to 12-bit values, so the range of data is no different
from the differential configuration. Consequently, the data returned contains only even numbers between 0
and 4094.
Continuous scans
When running
cbAInScan() with the CONTINUOUS option, consider the packet size and the number of channels
being scanned. To keep the data aligned properly in the array, make the total number of samples an integer
multiple of the packet size and the number of channels in the scan.