The programs available include:
To connect to another computer, at the DOS prompt, enter
To transfer a file between the PC disk and a Unix account or ant ftp server, use the following steps:
Some useful commands are:
Each device connected to the GPIB bus must have its own GPIB Address. Each instrument provides a different mechanism for setting its address, so see the documentation in the library on the instrument you wish to use.
For experiments where data taking via GPIB occurs on a regular basis some pre-written LabVIEW programs have been provided to make data taking a comfortable, and pleasant experience. Currently the critical opalescence and ferroelectric experiments have data collection programs written for them.
While these programs make it easy to read data from the devices you should be very careful to understand what the settings on the meter mean and to choose them correctly.
Both the range and resolution settings may affect the current the meter uses to measure resistance.
The only interface to the EG&G 5209 lock-in is through the Generic Logging program.
The only interface to the K485 is through the Generic Logging program.
On the desktop of the critical opalescence machine there is a folder called LocalApps. Inside that folder you should find a shortcut named Data Collection for Critical Opalescence Experiment. Double clicking that shortcut will open up a LabVIEW program which will manage data collection from the two HP 34401A multimeters. If you want to modify the program please make a copy of all the relevant VIs (Virtual Instruments) in your own directory.
Start the VI running by clicking the arrow in the toolbar. Then click on the Configure button for the first HP multimeter. This will bring up a dialog box to configure the meter you wish to use to read the resistance of the thermistor. Configure the device appropriately (make sure to set the GPIB Address correctly). Then click the Done button at the bottom of the configuration screen to send the meter the proper configuration commands. If the meter beeps then something went wrong (this appears to happen on occasion, and if it does just reclick the configure button and click done again to resend the configuration string). The readings from this meter will be plugged into the formula given earlier before being written to the log file to give temperature in degrees C. The raw resistances will also be written to the file. After the configuration has been completed read §6 on how to operate the rest of the program. Any further changes to the configuration may only be done by stopping and restarting the logging program. After you are satisfied with the configuration of your meter you may save the configuration to a file so you can reload it quickly later by clicking on the Save Config button in the configuration dialog.
Make sure to write down the settings you chose for the meter so that you know the resolution of the numbers written to the logfile (as they are written with a fixed maximum precision) or use the Save/Load Config feature to keep track of it, but write down what file you saved the config to.1). The resistance measurement is done by a Keithley 193 System DMM. In the LocalApps Folder on the desktop you should find an application called Ferroelectric Temperature Logger. Double clicking that should start up the program to log the temperature of the bath to a file. Click the arrow in the toolbar to start the VI running. Then choose the ``Configure'' button for the K193. The GPIB address of the meter should be 30 (to change this see the manual). Use of the filtering feature of the K193 is suggested (the details of the filtering are described, once again, in the manual). When done with the settings click the Done button to close the configuration screen. Any further changes to the configuration may only be done by stopping and restarting the logging program. The meter should click and start displaying Kohms. After you are satisfied with the configuration of your meter you may save the configuration to a file so you can reload it quickly later by clicking on the Save Config button. See §6 on how to operate the rest of the logging program. There is a formula section on the front panel where you may specify the conversion formula from temperature to resistance. If you do change it you may want to right click the box and select ``Data Operations'', ``Set current value to default'' to avoid having to retype your changes later.
There is also a program tailored for doing recording from two HP 34401A multimeters (which you may decide to use for looking at hysteresis curves). The interface to this program is basically the same as that for the temperature logger and indeed both programs can be run simultaneously.
Make sure to write down the settings you chose for the meters so that you know the resolution of the numbers written to the logfile (as they are written with a fixed maximum precision) or use the Save/Load Config functionality.
In the ``Logfile Path'' type the name of the logfile you wish to write to. You should make a directory c:\user\yourname\ to store any important data, so the logfile for a given run might be c:\user\yourname\mmddyy.txt. If this is an old logfile that you want to append the data to (for example you stopped the data collection a few minutes ago and want to continue again) then make sure the ``overwrite logfile'' setting is false before continuing. If overwrite is false, the new data uses the same time base as the old logfile, that is the first column, time in seconds since logging started, is correctly calculated with respect to the initial logfile starting time.
Set the delay between readings to an appropriate number (for example 10 seconds) so you do not log more data than you can handle in an analysis program. The number in the delay setting is in milliseconds.
Click the large ``Collect Data'' button and if all is working well then the Run Indicator should turn from Red to Green. If it does not then look at the error indicator box and try to determine what went wrong. Worse comes to worse close the data logging window then restart it and try again (don't forget to click the Configure buttons before running).
If you want to pause data taking click the Pause button. If you want to stop data taking press the Stop button (this may take a few seconds to have an effect depending on what the delay between readings is).
Now the meters are reading every so often and the readings are being written to the log file you specified with a timestamp which says when the readings were taken. The format of the logfile is described in the next section. You may check that the logfile is being created by opening the logfile in notepad or some other file viewer.
Remember to CONFIGURE the device before you start logging.
After opening this program you will want to set the path for the logfile to what you are writing to in the logging program and click the run arrow in the toolbar.
The indicator ``Data Began'' should tell you when the logfile was first written to. The selections for datasets are now sized to the number of data columns in the file (4 for critical opalescence has time, resistance, temperature, ratio; 3 for ferroelectric time, resistance, and temperature).
This program provides two different graph types to watch your data with. The first is a ``Dual Strip Chart'' which displays two data sets as a function of time. For the critical opalescence experiment it might be useful to look at both the ratio and the temperature at the same time, so in the ``Dual Strip Chart'' area of the program set the First Plot to Dataset #2 and the Second Plot to Dataset #3 and click the Create button. This should pop-up a new window with an empty graph in it. You have to go back to the initial window and click the green ``Read Data'' button to begin sending data to the graph. You should now see the data as it is being collected. See the dual strip chart user interface section for more information on playing with the graph. If there is a tremendous amount of data in the logfile you might click ``Read Data'' before you create the graph so as to catch up to the end of the logfile. If you want to skip a large section of the file (if for example you are appending to a large data file and want to look at only the end) then modify the percent skip option before starting the VI.
The second type of plot is an ``XY Plotter''. This can be used to display either a real XY plot (one dataset vs. another) or just a single plot strip-chart (dataset vs. time). To watch the temperature as a function of time for the ferroelectric or critical opalescence experiment set x-axis to time and y-axis to dataset #2 and click the Create button and the Read Data button (if you have not already). For the critical opalescence experiment it might be nice to watch the ratio as a function of temperature, in this case set the x-axis to dataset #2 (temperature) and the y-axis to dataset #3 (ratio). See the later section on the user interface for the XY plotter to determine how to change the x-axis labels from time to a real decimal number (for displaying a real XY plot).
You may create up to five of each type of graph of the logfile by repeating the procedure above (you only need to click Read Data once either before or after you create the graphs).
There is also a program to review an old logfile that does not update in realtime, the ``Log File Review''. In the window that pops up, change the Path for logfile to be the logfile you are writing to with the data logging program and then select the run arrow in the toolbar. This program does not update in real-time and instead are geared toward reviewing a logfile that perhaps you left running over the weekend, or last night. It makes review plots much faster than loading the data through the ``Real Time Log File Plotter''.
To zoom in on a region turn off the auto-scaling features of the plots, and then select the magnifying glass and select a region. Holding the left button on the magnifying glass allows a selection of zoom types (zoom in y-axis only, zoom in area, etc.).
When using the dual-xy plotter this interface becomes a bit more complicated as there are really two plots stacked one on top of the other with a common x-axis. Using the toggle for showing one graph or both graphs in conjunction with the palette controls allows for control of both plots.
To change the x-axis from a time display to a decimal display (if you are viewing a real XY plot), press the right mouse button over the button right next to the x-axis auto-scaling tab and select the formatting menu.
It is recommended that you experiment with the logging programs and visualization tools to find the features available.
There should be a link to the program in the LocalApps directory called Generic Logging Program. The interface is the same as for the previous programs except in this case one is able to choose the device to Configure. Use the first few device slots and leave the rest as None. Make sure to click the checkbox under ``Log Raw'' for the devices you want to write to a logfile.
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