to
cause the
digital line to be turned on if the value of the selected item is
greater than or equal to the comparison value. Select 
to turn the line on if the
value of the
selected item is less than or equal to the comparison value. The Digital Out feature allows you to control up to 3 output lines of a Digital Control Unit (DCU) connected to DIG/SONIC 1 or DIG/SONIC 2 of a compatible data-collection interface (e.g. LabQuest or LabPro). Each of the three lines can be individually controlled based on user-configured conditional statements. This allows you to develop projects that turn on and off DC motors, lamps, LEDs, buzzers, and other DC electrical devices based on sensor readings or time, for example. You can even develop more elaborate projects, such as a heating and cooling system, a fixture to follow the sun's trajectory, or an automated scientific apparatus.
Use the following procedure to set up the DCU:
You can test the 3 output lines of the DCU by selecting Line 1 On, Line 2 On, and/or Line 3 On. The LEDs visible through the transparent top of the DCU will turn on when the line is on. This is a good way to test that your DCU and electrical device are working properly before running your experiment.
Select the ouput line you want to control and then create an appropriate conditional statement based on your project.
Select to
cause the
digital line to be turned on if the value of the selected item is
greater than or equal to the comparison value. Select to turn the line on if the
value of the
selected item is less than or equal to the comparison value.
The comparison value is a value you define. There are two methods to set this value. One way is to manually enter a value directly into the Digital Out dialog box. Using this method, the comparison value is static during the experiment.
The other method for setting a comparison value is to choose a User Parameter from the drop-down menu at the far right. The default User Parameters include pi, Limit1, Limit2, and Limit3. Select the User Parameter and click the OK button to close the Digital Out dialog box. Choose Parameter Control from the Insert menu, double-click the Parameter Control box, and select the User Parameter that was selected as your comparison value. The Parameter Control gives you the ability to update the User Parameter value as the experiment runs. This provides the user with a dynamic comparison value.
Choose AND, UNTIL, or OR
to set additional conditions . For example, if you would like your line
to turn on within a window of 20 to 25 degrees, you could configure
line 1 to turn on if the temperature is
20 AND the temperature is
25.
When using additional conditions the logic of when a line turns on and
off might become confusing. Consider creating a logic table to
understand how the line reacts during the experiment.
You can choose when to activate the digital output. If Start activation when dialog is closed is selected, your settings will take effect when you select OK in the Digital Out dialog. The other option is to select Start activation when experiment run is started (Collect button clicked). With this option, digital output will start when you click the Collect button.
Note: The Digital Out feature is unable to scan all data at fast data collection rates. This may mean that peaks or valleys that fall above or below the user-defined comparison value, but are of very short duration, might not activate or deactivate a line as configured.
For complete details about the Digital Control Unit, consult the Digital Control Unit (DCU) Manual that comes with the unit. The manual can also be downloaded from the Vernier web site www.vernier.com.