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USB-AOUT
Analog Output Module
Installation and Operation Instructions
Description
The USB-AOUT is a digital-to-analog accessory that connects directly to the 10-pin input connector
on the Ocean Optics USB2000 or USB4000 Spectrometer. It emits an analog current ranging from 4 to
20 mA (based on a user-configurable scale) from Pin 8 of its 10-pin output. The analog current varies
based on a specific wavelength intensity obtained from OOIBase32 or SpectraSuite Spectrometer
Operating Software. The USB-AOUT does not require an external power supply, as the spectrometer
powers the unit via the accessory connector.
The USB-AOUT is an ideal solution for system integration configurations. It is designed to be a
custom configurable trigger mechanism based on current levels. You must configure the specific
events to be triggered separately in your configuration.
Parts Included
The USB-AOUT ships with the following items:
• USB-AOUT digital-to-analog output module
• Thumbscrew (to secure the USB-AOUT to the spectrometer)
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USB-AOUT Installation and Operation Instructions
Using the USB-AOUT
The following sections provide instructions on setting up and using the USB-AOUT.
Connecting the USB-AOUT
► Procedure
Follow the steps below to configure the USB-AOUT:
1. Remove the USB-AOUT and thumbscrew from the product packaging.
2. Screw the thumbscrew into the metal connector located under the 10-pin output of the USB-
AOUT.
3. Connect the 10-pin input connector of the USB-AOUT to the 10-pin connector on the
USB2000 Spectrometer or the 22-pin connector on the USB4000 Spectrometer and secure the
USB-AOUT using the thumbscrew.
4. Connect the fiber, USB cable, etc. to the spectrometer as you normally would.
5. Connect the appropriate detection mechanism to Pin 8 of the 10-pin output connector on the
USB-AOUT.
6. Connect the ground wire to Pin 6 of the 10-pin output connector on the USB-AOUT.
You have now connected the USB-AOUT for operation.
Configuring the USB-AOUT in OOIBase32
The OOIBase32 and SpectraSuite operating software allow you to customize the intensities that
produce certain current levels in the USB-AOUT. This is achieved by configuring the USB-AOUT in
the Time Acquisition Channels configuration dialog box in OOIBase32. Using this feature in
OOIBase32, you can customize the USB-AOUT so that it outputs a current that scales (with a
maximum output of 20 mA, based on intensity) at the desired wavelength.
For specific instructions on using OOIBase32, consult the OOIBase32 manual at the following web
address:
http://www.oceanoptics.com/technical/ooibase32bit.pdf
► Procedure
Follow the instructions below to configure the USB-AOUT options in the Time Acquisition dialog
boxes of OOIBase32:
1. Ensure that OOIBase32 is in the desired mode of operation.
2. Open the Time Acquisition Channel Configuration dialog box (see the OOIBase32 manual for
specific instructions).
3. Select the Channel Tab associated with the USB-AOUT-equipped spectrometer.
4. Select the Enable button to enable Time Acquisition on the channel tab.
5. Select the Enable D/A Output (Channel X) check box on the channel tab.
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USB-AOUT Installation and Operation Instructions
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
USB-AOUT section below for instructions on customizing the current output scale.
Setting the Dynamic Detection Range of the
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 usi n g the follo wing 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.
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Scope Mode Example
If you are in Scope Mode and wish to scale the 4-20 mA output for Scope Mode intensities
between 1000 and 3500:
Factor = 5 / (3500 – 1000) or Factor = 5 / 2500
Thus, for this particular Scope Mode experiment, the Factor should be equal to .002
3. Click the Apply button to set the values, and then click the OK button to close the Time
Acquisition Channel Configuration dialog box.
You have now configured the USB-AOUT scale to output 4-20 mA based on the appropriate intensity
scale for your mode of operation.
Configuring the USB-AOUT in SpectraSuite
You must define a trigger. A wizard walks you through the necessary setup steps.
► Procedure
1. Click on the Tools menu item.
2. Choose Triggers and then click on Configure New Trigger.
3. Select Continuous current out and click the Next button.
4. Specify a name for your trigger and click the Next button.
5. Highlight the spectrometer to provide the intensity values. This may or may not be the
spectrometer with the attached USB-AOUT device. Then click the Next button.
6. Click the radio button corresponding to the type of monitoring you wish to perform. Enter a
wavelength or range of wavelengths, as needed. For the integration option, you must also
choose the method of integration (rectangular, trapezoidal, or Simpson’s). Then click the Next
button.
7. Highlight the spectrometer with the attached USB-AOUT you wish to control. When you click
the Next button, the monitoring will begin and the USB-AOUT will begin generating the
current-level signal accordingly.
8. Click the Finish button to exit the wizard.
To review your trigger settings, select on Tools | Triggers | View Triggers from the menu.
To remove or delete a trigger, select on Tools | Triggers | Remove a Trigger.
Note
When you remove a trigger, the USB-AOUT will continue to put out the current-level
that was in effect at the moment you removed the trigger.
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You can verify correct operation of your trigger and the USB-AOUT device by connecting a
multi-meter to the device. Pin 6 is ground. Pin 8 is “hot.” Be sure to set your multi-meter to
the milliamp setting. Then control your light source to see the corresponding change in
current-level. If the light source varies too rapidly, your multi-meter will not reflect the
transient current-level variations. Small variations in the current-level are normal, on the order
of a few hundredths of a milliamp, even under seemingly steady light conditions.
USB-AOUT Specifications
USB-AOUT Pinout Information
The following section contains information on the 10-pin output connector on the USB-AOUT.
Pinout Diagram of the 10-Pin Output Connector on the USB-AOUT
Pinouts
Pin Function
1 V
2 RS232 Tx
3 RS232 Rx
4 Lamp Enable
5 Continuous Strobe
6 Ground
7 External Trigger In
8 Signal Output (4-20 mA)
9 I2C SCL
10 I2C SDA
or 5V in
USB
4-pin TP Connector
The 4-pin TP connector on the side of the USB-AOUT has no function.
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