Measurement Computing DaqBook 2000 Series - Manual (Page 71)

DaqBook/2000 and DaqOEM/2000 Series 959095 Calibration 9-1
Calibration 9
Overview …… 9-1
Using DaqCal.exe …… 9-1
Overview
The DaqBook/2000 and DaqOEM/2000 Series devices are digitally calibrated at the factory. The digital
method involves storing a correction factor on the circuit board for each range at the time of calibration.
Whenever a particular range is selected, the appropriate calibration constant is automatically applied to a
compensating DAC, thereby calibrating the specific range. The result is that readings generated by the A/D
are already calibrated, and do not require additional processing.
This is significantly better than the calibration method in which readings are adjusted in software after they
are transferred to the host PC. That method reduces the dynamic range of the A/D, and can adversely
affect the speed at which the PC obtains a calibrated reading.
The DaqBook/2000 and DaqOEM/2000 Series devices include a user-cal mode, whereby the user can
adjust the calibration of the unit’s board, without destroying the supplied factory calibration. This is
accomplished with two distinct calibration tables in the unit’s on-board EPROM, one which contains the
factory calibration factors, and the other which is available for user calibration.
Using DaqCal.exe
When calibration adjustments are needed they should be completed in the following order:
1.
2.
3.
4.
5.
6.
7.
8.
PGA Input and Output Offset
Sample/Hold Offset
A/D Offset and Gain
VDC Voltage Reference
DAC0 Full-Scale 1
DAC1 Full-Scale 1
DAC2 Full-Scale 1
DAC3 Full-Scale 1
1 DAC Full-Scale only applies to DaqBook/2020, DaBook/2001, and DaqOEM/2001.
A Windows-based program, DaqCal.exe, is used to calibrate Daq systems, including analog expansion
cards. DaqCal.exe is used in conjunction with:
• a 4.5 digit, digital multi-meter
• an adjustable voltage calibrator
• an ambient temperature meter
To use the calibration program:
1. Launch DaqCal.
Note: DaqCal is installed automatically from your data acquisition CD as a part of product
support. This takes place during software installation. DaqCal’s default location is the
IOtech DaqX Software folder, in the Programs group.
2. When DaqCal opens you will be prompted to select your device from a list. After doing so,
simply follow the illustrated on-screen instructions.