Question Answer

DAQ Plot ► Support ► Question Answer

Below are answers to commonly asked questions about DAQ Plot. If you have a question please mail support@vvi.com.

Q: Why do DAQ Plot windows not look like the windows annotated in this manual?

It is probably because you are using the Simple Preference Style and in order to show all the features this manual describes the Professional Style. See the next question for additional information.

Q: How do I turn on the Pro features?

See: Preference Style.

Q: How do I totally reset DAQ Plot?

Launch the Terminal application and type this at the command line:
rm ~/Library/Preferences/com.vvi.DAQPlot.plist rm -r ~/Library/VVI/DAQPlot
Then relaunch DAQ Plot and reconfigure it. There should not be a situation where you need to reset DAQ Plot, but a reset can be used just incase.

Q: I attached the DAQ device but the program still says it is not attached. How do I get DAQ Plot to recognize the device?

First configure the device. See Hardware Preferences for example. Set the correct identification string and then click the Apply button. Then go to the Main Preferences and select the device type and click Start Acquisition.

Q: I just installed DAQ Plot and inserted the license key but it doesn't work. What do I do?

Try rebooting your computer. DAQ Plot installation does not need a reboot, but some computers may be configured in such a way that a reboot is required.

Q: What is the data limit of DAQ Plot?

By default, DAQ Plot will store the last 864,000 values per channel. At any point in time all data is retained until you reach 864,000 values per channel and then the last 864,000 are retained. For example, if you have sampled 1,000,000 points then DAQ Plot will retain the last 864,000 values and the first 136,000 values are lost forever. You can adjust this parameter. For additional information see Buffer.

Q: The voltage readings and curves of terminals I have not connected seem to dance around, how do I prevent that?

Turn all channels off except the ones you are using by clicking the switch next to the channel number in each row of the hardware preference pane. Turning off unused channels will cause the hardware to sample faster as well as eliminate spurious channel output whose values are voltage floaters (have no potential reference) and may appear random in the output.

Q: Is DAQ Plot a real-time data collection application?

Technically the answer is no. In practice, DAQ Plot is designed so that there is no data loss or failure of any kind. However, you can overwhelm your computer and cause data to be lost. For example, if you run a huge program that fills up all your computer's RAM and it starts paging and at the same time you are using the backup option then there is a chance that the hard disk backup and paging operations will temporarily lock one another and for that brief moment data will be lost. For additional information see Hardware Failure.

Q: I want to collect data with DAQ Plot, but want to post-process it myself. How do I do that?

Turn on the DAQ Plot backup facilities and then when you quit DAQ Plot, or actually at any time even while running DAQ Plot, you can write a program to read the backup files and process the data yourself. The backup files always contain the most recent data. See Decoding Backup for additional information. You can also finish a data run and Export the data to a spread sheet using tab delimited text.

Q: Where do I get sensors that can work with DAQ Plot?

You can use the DAQ hardware and software to measure and display nearly anything. All you have to do is find the appropriate sensor to convert what you want to measure into voltage of the appropriate range (and amp limits).
For example Digi-Key sells discrete sensors. If you click on that URL (http://www.digikey.com) and search for "temperature sensor LM34" (without the quotes) you will get a list of various temperature sensors. Click the LM34CZ-ND link to by your own temperature sensor. You can also buy other sensors by typing in other keywords, for example, type "pressure sensor".
Another good source for sensors is Omega. They sell packaged sensor devices so you will not have to solder the leads to a wire.

Q:	Why do DAQ Plot windows not look like the windows annotated in this manual?
	It is probably because you are using the Simple Preference Style and in order to show all the features this manual describes the Professional Style. See the next question for additional information.

Q:	I attached the DAQ device but the program still says it is not attached. How do I get DAQ Plot to recognize the device?
	First configure the device. See Hardware Preferences for example. Set the correct identification string and then click the Apply button. Then go to the Main Preferences and select the device type and click Start Acquisition.

Q:	I just installed DAQ Plot and inserted the license key but it doesn't work. What do I do?
	Try rebooting your computer. DAQ Plot installation does not need a reboot, but some computers may be configured in such a way that a reboot is required.

Q:	The voltage readings and curves of terminals I have not connected seem to dance around, how do I prevent that?
	Turn all channels off except the ones you are using by clicking the switch next to the channel number in each row of the hardware preference pane. Turning off unused channels will cause the hardware to sample faster as well as eliminate spurious channel output whose values are voltage floaters (have no potential reference) and may appear random in the output.