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Datadisc Family FAQ

Version history  

System requirements

Calculation

Fitting a function

Networking

Recording data

Smoothing

Transferring data

Manipulating data with the table

Non-Western versions of Windows

Installation problems

Au / Ag - confused?

Serial ports COM10 and higher

Datamass for Windows questions

Most Datamass questions are covered in the appropriate Datadisc for Windows section above. Click here for specific Datamass for Windows questions.

Datadisc for Windows

Q. Can I use Datadisc on a network?
A. Yes ! Modern 32 bit networks are very complex to administer and, importantly, they protect strongly against unauthorised tampering so Datadisc Ag MUST be set up by a knowledgeable person ()about the network) who has Administrator rights.. Information on network installation.
Q. How do I choose which function to fit? [More questions on fits]
A. Datadisc currently offers six functions to fit to datA.
The buttons show the functions and their equations.
Linear
y = A + B x
Use this whenever you expect the data to fit a straight line graph.

If you prefer to "draw your own line" by eye then select the Fit: Manual option from the menu instead !

Quadratic
y = A + B x + C x2
Use this for all "square law" functions. It doesn't matter if the expected equation does not have one of the elements of the equation that Datadisc fits.
Example: Dropping a ball and measuring distance we expect that . But, if we are careful to start the ball from rest (no initial velocity) then the equation is and we expect the fit function to show near zero values for A and B. However, it is likely that we will not measure with the starting distance being zero so there is likely to be an A value in practice.
Logarithmic
y = A loge(Bx)
Use this where a logarithmic y dependency is expected.
Exponential
y = A eBx
Use this for exponential decay - eg Protactinium decay curve.
Negative Exponential
y = -A eBx

This will fit functions that grow exponentially towards zero. It is useful in fitting data that shows an exponential growth to a non-zero maximum (eg charging a capacitor) if you first re-calculate the y values to make the maximum value zero (ie subtract the expected maximum). This will then fit more reliably and quickly than the next function.

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Exponential to maximum
y = A(1 - eBx)
Datadisc can find an exponential growth fit and estimate the maximum value at the same time but it takes more time and may be less reliable with poor datA. The A value is the maximum value that is being approached.
Example: charging a capacitor.
Q. How can I fit data to a function Datadisc does not provide? [More questions on fits]
A. Consider whether you can perform a calculation on one channel first to create a function that can be fitted.
Example: Boyle's Law. We expect P µ 1/V. Hence if we calculate a channel of 1/V values then a linear fit of the P channel against the 1/V channel should be obtained.
Q. How do I calculate a function which Datadisc does not provide?
A. There are two possible answers now.
One is to enter your own formula in the large button provided (and obviously select that button). The syntax is relatively free and a wide variety of functions can be used. (More information)
The other answer is to perform a sequence of calculations. Then delete the intermediate stage channels. If you are feeling brave you can tell Datadisc to put each result in the same channel, over-writing the previous stage.
Example: Calculate e1/x for a channel. First calculate 1/x putting the result into a spare channel. Then calculate enewchannel putting the result in the same channel.
Q. How do I fit a function to just part of my data? [Another question on fits]
A. The Fit window has a button you may not have noticed - - Click this to see text boxes that show the first and last x values for the datA. Select the x channel you require for your fit and then adjust the values in the boxes. Be careful if time is involved to check which units the box is using.
You can set values outside the data range to get an extrapolation. (There are some restrictions to this but you will get a message to explain if your extrapolation is too ambitious.)
Q. Why are there three function in the fit option that look almost the same?
A. The three exponential functions all fit basically the same kind of curve but different fit functions are required for the case where the A parameter is negative or where an exponential growth is fitted and you do not know the limit being approached. The latter fit takes longer and is more likely to fail with bad datA.
Q. What is the best way to smooth my data? [Another smoothing question]
A. The best way to smooth data is probably to fit the expected function but not all data sets are suitable for this. Smoothing is usually cosmetic - it can only lose significant information from your data, it cannot create significance where it does not exist.
Datadisc currently offers two smoothing techniques:
Fourier smoothing removes higher frequency components from the function. It is a valid technique when you know that the real data could not have changed at a rate implied by the "noise" in the recording. You can choose the degree of smoothing on a scale of 0 - 100 in preferences. Experiment to see what results you get. Always save the original data first.
Median smoothing is effective in removing odd rogue points from data that is expected to change smoothly.
Q. Why isn't the smoothing function available with a graph that requires calibration using a keyboard? (Charles Bonello, Malta)
(e.g.The variation of Magnetic flux density B vs distance d for a straight wire)
[Another smoothing question]
A. The smoothing function only really works properly with data where the x values are evenly spaced - as they always are when recording against time so we restrict this to data plotted against time only.
Q. When one repeats the smoothing process a number of times does the graph actually become smoother? (Charles Bonello, Malta)
A. With the Fourier smooth option (see Utilities: Preferences) the smoothing does carry on changing the data every time (and the danger of losing "real structure" increases). For the median method it soon settles down to no change.
Q. How can I get my data into Excel? [Another data transfer question]
A. There are at least two ways.
You should be able to select all the data in the table and use Copy from the edit menu, followed by Paste into Excel.
Use the button at the top left of the table to select all the datA. And don't worry if your table extends to several pages - selecting all like this will select all the datA.
Alternatively you can save the data using a text format - we recommend CSV. Use ".CSV" as your file extension for the save and the data will be in a form Excel can readily read.
When opening the file into Excel you will need to select "Text files (*.prn, *.TXT, *.CSV)" or similar description from the list at the bottom left of the Open window.
Q. How can I record values when I choose? [Another recording question]
A. We call this a "spacebar" recording - admittedly a name of rather historical significance as the idea was that data was recorded every time the spacebar was pressed. It is now more usual to click the record button at the top of the recording form but the spacebar still works as long as you keep the Datadisc Window "in focus".
Use the recording demon (Record...) to set up your recording choosing your axes and selecting "spacebar" style.
Q. What is a frugal recording? [Another recording question]
A. Frugal recording is "intelligent recording". Recording as many points as possible over a period will probably catch your event but what a lot of data to wade through in the table! The point of a frugal recording is to record a set of values only when the values have changed significantly. Frugal recording against time is particularly valuable for investigations when you can't predict when rare events will happen (animal behaviour studies for example).
Datadisc can also record frugally when time is not on the x - axis. Valuable when you want to get on with controlling the experimental parameters and leave Datadisc to record at sensible ordinates.
Q. Why can't I choose 30 ms as the recording interval with DL plus? [Another recording question]
A. PCs have a clock that does not "tick" very frequently and this follows through to Windows. It is therefore difficult to time data capture precisely at particular interval below about 100 ms interval. What we do therefore is estimate how fast to run the code for a particular duration and number of points and can only give an estimate of the interval. The actual interval is computed accurately during the recording and stored with the datA.

(Newer interfaces such as the Logbook XD do allow recording at such intervals - down to 10 ms or less.)

Q. I want to make a recording including data I have to type in - what do I do?
A. Select Spreadsheet entry from the Measure menu. The data you type in here remains as text until you select Exit and return to Datadisc from the Spreadsheet File menu. Until then you can edit and enter your data freely.
Q. Can I use Datadisc to present and manipulate data generated elsewhere?
A. Yes. There are several ways to get data in to Datadisc. Get the data into comma-separated form first if you can. (Word tables are handy here - if you can get the data into a table in Word then just "Convert table to text" choosing a comma as the separator and save the file in text form using a .CSV extension to the filename).
The Datadisc Open command will then offer you the choice (bottom left) to list CSV files for loading.
Q. How can I sort my data? [Another table question]
A. You can do this with any data where there is no time channel recorded. Select the channel you want to sort in the table (click on the column heading) and then choose Edit: Sort. Data in the other channels will be adjusted accordingly (e.g. if reading 2 and 3 have to exchange positions then all the data for these readings will exchange positions, not just the channel you have chosen). You can sort part of the data by selecting part of a column in the same way. The same principle applies to the Spreadsheet. Data is always sorted in ascending order. (No-one has ever asked to do it any other way.) Note that X/Y recordings without a time channel have their dated sorted automatically based on the X-axis at the end of a recording.
Q. My data table contains hundreds of readings and it takes for ever to scroll through it and the print-outs are huge! [Another table question]
A. Assuming that you have a gradual change in your recording, you can choose to display a selection of the data (every 10th point or whatever you choose). Click on the box at the top of the table and choose one of the values on offer or enter your own. This can be very useful if you want a sensible length print-out of actual values.
Q. I don't want to print all my data channels in the table, but don't want to delete any. [Another table question]
A. You can hide channels temporarily by clicking on the buttons at the top of the table so as to display just the channels you want. Clicking the buttons again will bring them back. (You can achieve the same effect with Data: Table Options)
Q. I want to round off the figures in my table. How do I do this? [Another table question]
A. Datadisc displays the figures according to the resolution for each channel. You can go to Data: Edit Calibration, choose the channel and change the figure (if it is set to 0 then Datadisc will try to guess what you want). This is particularly appropriate if you are entering integers in the spreadsheet. You may need to experiment to get the effect you want.
Q. I don't like the way the table displays the time. Can I change it?
A. Datadisc tries to choose a suitable time format. If you don't like it then you can go to Data: Table Options and choose another one.
Q. Does Datadisc work in non-Western Windows versions?

A. Datadisc Ag has been modified and tested to work in Chinese editions of Windows. There are still some problems to iron out in some versions of non-Latin Windows which we are working to fix (email us with your experiences please). (The program itself is still in English though!)

Datamass for Windows

Q. Can I use balance "X" with Datamass?
A. We guarantee to support all the balances in the Philip Harris Education catalogue. Users of other balances with serial interfaces have successfully used Datamass. You will need a suitable serial lead and to set the appropriate configuration for communication with your balance. Unfortunately we do not have the resources to test and support every balance on the market.
Q. The graph of my recording has steps in it. This doesn't happen when I use sensors!
A. Datamass takes the exact reading it gets from the balance. If you use only a small part of the balance range (say 0.1g when it reads to the nearest 0.01g) then this is inevitable. Ensure that you get a greater mass change during the experiment. If you have an experiment where there will be times when the mass changes quickly initially and then slowly (e.g. the marble chips and acid experiment) try doing a frugal recording so that unnecessary points are not recorded and the steps will not be obvious.
For this reason, it is unlikely that balances that read to 0.1g will be much use for DataLogging although they may produce acceptable bar charts. If you attempted to make a sensor recording using such a small part of the operating range it is likely that electronic noise would render it meaningless - the balance has already removed the noise for you!
Q. Why can't Datamass be used to do recordings at shorter intervals?
A. Firstly, obtaining data from balances is quite slow - compared to the Philip Harris interfaces they take a long time to respond to a request for the current reading. Secondly, most balances will only transmit data when the reading is stable - they are not suitable for experiments where mass changes rapidly.
Q. How do I record a bar chart / histograms with Datamass?
A. If you choose the Mass Only recording option the data will be presented as a bar chart automatically. When you finish your recording, you can then open an additional window for your histogram.
Q. Can I use Datamass to produce a bar chart / histogram for other data?
A. Yes, if you go to the Graph: Set Axes dialogue you can choose Bar Chart and can include any or all of the channels recorded. Once this is done, the Histogram option can be activated. If you want to change the display permanently to this form, be sure to resave your datA. Of course, you can always reverse the change by reverting to the original X-axis.
Q. How do I get labels on my bar-charts like the sample file?
A. You can enter the text labels while you record by using the Recording Table. This works like a Spreadsheet but allows you to include balance and sensor data along with text (and keyboard data). Alternatively, you can copy your data to the spreadsheet and add a set of labels after you have completed your recording in the usual way.
Q. Can I use Datamass to record with just sensors and no balance?
A. Yes, but only if there is a copy of Datadisc installed on the same computer! Datamass is designed primarily for use with balances. We are bound to sell fewer copies of Datamass than Datadisc and this has been done to support our development costs. Sorry!
Q. I have an Oertling balance but the Oertling Datalogging option in the measure menu is not available.
A. This is a special option for the D-series balances (only). It will only appear if you enable it using the Utilities: Set Balance Type dialogue. Enable Oertling Balance Data Transfer, but this will be of no value for other kinds of Oertling balance which do not support this.
A. We guarantee to support all the balances in the Philip Harris Education catalogue. Users of other balances with serial interfaces have successfully used Datamass. You will need a suitable serial lead and to set the appropriate configuration for communication with your balance. Unfortunately we do not have the resources to test and support every balance on the market.
Q. The graph of my recording has steps in it. This doesn't happen when I use sensors!
A. Datamass takes the exact reading it gets from the balance. If you use only a small part of the balance range (say 0.1g when it reads to the nearest 0.01g) then this is inevitable. Ensure that you get a greater mass change during the experiment. If you have an experiment where there will be times when the mass changes quickly initially and then slowly (e.g. the marble chips and acid experiment) try doing a frugal recording so that unnecessary points are not recorded and the steps will not be obvious.
For this reason, it is unlikely that balances that read to 0.1g will be much use for DataLogging although they may produce acceptable bar charts. If you attempted to make a sensor recording using such a small part of the operating range it is likely that electronic noise would render it meaningless - the balance has already removed the noise for you!
Q. Why can't Datamass be used to do recordings at shorter intervals?
A. Firstly, obtaining data from balances is quite slow - compared to the Philip Harris interfaces they take a long time to respond to a request for the current reading. Secondly, most balances will only transmit data when the reading is stable - they are not suitable for experiments where mass changes rapidly.
Q. How do I record a bar chart / histograms with Datamass?
A. If you choose the Mass Only recording option the data will be presented as a bar chart automatically. When you finish your recording, you can then open an additional window for your histogram.
Q. Can I use Datamass to produce a bar chart / histogram for other data?
A. Yes, if you go to the Graph: Set Axes dialogue you can choose Bar Chart and can include any or all of the channels recorded. Once this is done, the Histogram option can be activated. If you want to change the display permanently to this form, be sure to resave your datA. Of course, you can always reverse the change by reverting to the original X-axis.
Q. How do I get labels on my bar-charts like the sample file?
A. You can enter the text labels while you record by using the Recording Table. This works like a Spreadsheet but allows you to include balance and sensor data along with text (and keyboard data). Alternatively, you can copy your data to the spreadsheet and add a set of labels after you have completed your recording in the usual way.
Q. Can I use Datamass to record with just sensors and no balance?
A. Yes, but only if there is a copy of Datadisc installed on the same computer! Datamass is designed primarily for use with balances. We are bound to sell fewer copies of Datamass than Datadisc and this has been done to support our development costs. Sorry!
Q. I have an Oertling balance but the Oertling Datalogging option in the measure menu is not available.
A. This is a special option for the D-series balances (only). It will only appear if you enable it using the Utilities: Set Balance Type dialogue. Enable Oertling Balance Data Transfer, but this will be of no value for other kinds of Oertling balance which do not support this.
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