Measurement Computing DaqBoard 3000USB Series - Manual (Page 39)

o Variable pre-trigger with infinite post trigger. This is similar to the mode described above, except
that the acquisition is terminated upon receipt of a command from the program to halt the
acquisition. Driver support only.
Calibration
Every range of a DaqBoard/3000USB Series device is calibrated at the factory using a digital NIST
traceable calibration method. This method works by storing a correction factor for each range on the unit at
the time of calibration. The user can adjust the calibration of the board while it is installed in the
acquisition system without destroying the factory calibration. This is accomplished by having 3 distinct
calibration tables in the on-board EPROM.
The user can select any of the three cal tables provided [factory, user, or self-cal tables] by API call or from
within software. Self-cal can be performed automatically via the included software and without the use of
external hardware or instruments. Self-cal derives its tracebility through an on-board reference which has a
stability of 0.005% per year.
Note that a 2-year calibration period is recommended for DaqBoard/3000USB Series boards.
Reference Note:
Chapter 4, Calibration, discusses using a temperature calibrator with a DaqBoard/3000USB
Series board.
Analog Output
DaqBoard/3001USB and /3031 Only
DaqBoard/3001USB and /3031USB each have four 16-bit, 1 MHz analog output channels. The channels
have an output range of -10V to +10V. This can be read from PC RAM or from a file on the hard disk. In
addition, a program can asynchronously output a value to any of the D/As for non-waveform applications,
presuming that the D/A is not already being used in the waveform output mode.
A program can asynchronously output a value to any of the D/As for non-waveform applications,
presuming that the D/A is not already being used in the waveform output mode.
Each of the analog outputs can be used in a control mode, where their output level is dependent on whether
an associated analog, digital or counter input is above or below a user-specified limit condition.
When used to generate waveforms, the D/As can be clocked in several different modes. Each D/A can be
separately selected to be clocked from one of the following sources.
o Asynchronous Internal Clock. The on-board programmable clock can generate updates ranging
from 19 hours to 1 MHz, independent of any acquisition rate.
o Synchronous Internal Clock. The rate of analog output update can be synchronized to the
acquisition rate derived from 1 MHz to once every 19 hours.
o Asynchronous External Clock. A user-supplied external input clock can be used to pace the
D/A, entirely independent of analog inputs.
o Synchronous External Clock. A user-supplied external input clock can pace both the D/A and
the analog input.
DaqBoard/3000USB Series User’s Manual 988093 Device Overviews 1-13