Ocean Optics USB-AOUT - Manual (Page 3)

USB-AOUT Installation and Operation Instructions
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6. Specify the wavelength you wish to monitor in the Wavelength (nm) box.
7. Enter the number of pixels surrounding the monitored wavelength to include in the Time
Acquisition process (if desired) in the Bandwidth (pixels) box.
8. Once these options are configured, proceed to Setting the Dynamic Detection Range of the
USB-AOUT section below for instructions on customizing the current output scale.
Setting the Dynamic Detection Range of the USB-AOUT in
OOIBase32
Once you configure the Time Acquisition options, you must configure the dynamic range of the
analog output. By using the Offset and Factor boxes, you can customize the current output so that the
final output is between 4-20 mA.
• In Scope Mode, OOIBase32 outputs wavelength intensity based on a 0-4095 count scale.
• In Absorbance Mode, OOIBase32 outputs wavelength intensity based on an absorbance scale
of 0-4.
• In Transmission Mode, OOIBase32 outputs wavelength intensity based on a 0-100 percent
scale.
• Relative Irradiance mode is a customized mode where you can determine the output scale of
OOIBase32.
► Procedure
Follow the instructions below to scale the data for your mode of operation:
1. Specify the low limit of your expected data range for the offset in the Offset box of the Time
Acquisition Channel Configuration dialog box.
For example, if you are in Scope Mode and wish to monitor intensity from 350-3500 counts,
enter 350 for the offset. If you are in Transmission mode and wish to use 20% for the low
threshold, enter a 20 for the offset, etc.
2. Calculate the factor for the Factor box of the Time Acquisition Channel Configuration dialog
box. Factor calculation is determined by the expected upper threshold of your measurement
and by the mode you are in. Calculate the factor using the following equation:
Factor = 5 / (Upper Threshold – Lower Threshold)
Absorbance Mode Example
If you are in Absorbance Mode and wish to scale the 4-20 mA output for absorbance
measurements between 1.5 and 3.5, calculate the factor as follows:
Factor = 5 / (3.5-1.5) or Factor = 5 / 2
Thus, for this particular Absorbance Mode experiment, the Factor should be equal to 2.5.
Transmission Mode Example
If you are in Transmission Mode and wish to scale the 4-20 mA output between the values of
15% and 95%, calculate the factor as follows:
Factor = 5 / (95 – 15) or Factor = 5 / 80
Thus, for this particular Transmission Mode experiment, the Factor should be equal to .0625.