User`s guide

Universal Library User's Guide Analog Input Boards - USB-1208 Series
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RegNum LOADREG1
Event notification
Even notification functions and methods supported
UL: cbEnableEvent(), cbDisableEvent()
UL for .NET: EnableEvent(), DisableEvent()
Event types: ON_SCAN_ERROR (analog input), ON_DATA_AVAILABLE, ON_END_OF_AI_SCAN
The USB-1208FS also supports ON_END_OF_AO_SCAN and ON_SCAN_ERROR (analog
output)
Hardware considerations
Acquisition Rate (USB-1208FS)
Since the maximum data acquisition rate depends on the system connected to the USB-1208FS, it is possible
to "lose" data points when scanning at higher rates. The Universal Library cannot always detect this data loss.
Maximum rates may be lower in Windows operating systems that predate Windows XP.
Most systems can sustain rates of 40 kS/s aggregate in BLOCKIO mode, and 1 kS/s aggregate in SINGLEIO
mode.
BURSTIO (USB-1208LS)
BURSTIO mode allows higher sampling rates for sample counts up to the size of the FIFO. The USB-1208LS
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 USB-1208LS 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 87). To avoid
the BURSTIO default, specify BLOCKIO mode.
EXTCLOCK (USB-1208FS)
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.
RETRIGMODE (USB-1208FS)
When using cbAInScan()/AInScan(), you can use RETRIGMODE to set up repetitive trigger events.
Resolution
When configured for single-ended mode, the resolution of the data is 11 bits (data values between 0 and
2047). However, the Universal 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 when the NOCALIBRATEDATA option is used.