The GLX has four screens for displaying data: Graph, Table, Digits, and Meter.
This chapter will describe the structure and use of each display.
Open any of the displays to monitor live data as it is collected. Open the Graph or Table to view previously recorded measurements or manually entered data.
G ra p h
The Graph plots data on a pair of axes. Use the Graph to view, compare, and ana-lyze data sets.
To Open the Graph
From the Home Screen, do one of the following:
press , the function key below the Graph icon;
use the arrow keys to highlight the Graph icon, then press ; or click the Graph icon.
From anywhere in the GLX environment, you can always open the Graph with the shortcut + .
In some cases, the Graph opens automatically when you connect a sensor.
The Graph Display
F1
The Graph icon on the Home Screen
F1
Active Fields
Active fields of the Graph
Active fields are the areas on the Graph (and other display screens) through which you control what data are shown. When you select an active field, a menu opens containing choices of data source, units, or run number. Follow the steps below to select an active field using the keypad.
1. Press to “light up” the active fields—shaded boxes appear around the active fields.
2. One of the shaded boxes is darker than the others, designating the high-lighted field. Use the arrow keys to move the highlight to the field that you would like to select.
3. Press again to select the highlighted field, which causes a menu to open.
To select an option from the menu:
• use the up and down keys to highlight the desired menu option, then press
; or
• press the number on the keypad corresponding to the desired menu option.
To turn off the highlight without selecting one of the fields, or to close a menu without selecting an option, press .
If you are using a mouse, you can left-click an active field to select it and open the menu, then click one of the menu options. (It is not necessary to press
first.)
Selecting a field with the mouse DataSource
Units
Data Source Units
Run Number
Highlighted field
on the keypad, press the number corresponding to the desired option.
or
Use the arrow keys to move the highlight to the desired menu option, then press ;
Press to light up the active fields.
Use the arrows to move the highlight to the desired field and press to open the menu.
Selecting a field with the keypad
Esc
Left-click the desired menu option.
Left-click one of the active fields.
Choosing Data to Display
Data Source A graph is generated from two data sources: one on the vertical axis and one on the horizontal axis. The possible types of data source are
• a sensor measurement,
• time (horizontal axis only),
• a calculation,
• manually entered numeric data, and
• manually entered text data (horizontal axis only).1
If you configure the Graph with data sources that already contain data, the data will appear immediately. If the selected data sources have not yet collected data, the Graph will initially be blank; when data collection starts, each data point will be plotted as it is acquired.
Data source menu for the horizontal axis
If there is at least one sensor connected to the GLX, the Graph will automatically set one of the sensor measurements as the vertical data source, with time as the horizontal data source. Select the vertical or horizontal data source field2 to choose a different source.
When you chose a data source, it replaces the previously displayed one.
See “Two Measurements” on page 23 and “Two Graphs” on page 24 for instructions on displaying two vertical data sources simultaneously.
If you do not see the sensor measurement that you want in the data source menu, select More to expand the menu.
For more information on selecting data from the Data Source menu when you are working with more than one sensor, or with a multiple-measurement sensor, see “Data Source Menus” on page 89.
Also from the Data Source menu, you can select Properties to edit the name and other properties of the currently displayed data set. See “Data Properties” on page 69 for more information.
Units Select the units field2 to choose different units (if available) for the chosen data source.
Run Number Select the run number field2 to choose a different data run. You can also choose to display no data.
1For more information on calculations, see page 41. For more information on manually entered data see page 32.
2To select a data source, units, or run number field
Keypad
1. Press to light up the active fields.
2. Use the arrow keys to move the high-light to the desired field.
3. Press again to open the menu.
4. Use the arrow keys to highlight the desired menu option and press ; or press the number on the keypad corresponding to the desired menu option.
Mouse
1. Click the desired field to open the menu.
2. Click the desired menu option.
Run number menu
In normal mode, one data set is displayed at a time. See “Two Runs” on page 24 for instructions on displaying two runs simultaneously.
The next-to-last option in the run number menu is Delete Run, which deletes the currently displayed run. That run will be deleted from all measurements, not just the one displayed in the Graph.
The last option in the run number menu is Rename Run. By default, data runs are names “Run #1,” “Run #2,” etc. When you select Rename Run, the GLX prompts you for a new run name. Enter the new name using multipress text entry (or an attached keyboard) and press to accept the change (or press to cancel the change). The new name will be applied to that run from all measure-ments, not just the one displayed in the Graph.
For more information on multipress text entry, see page 90.
Data Cursor and Coordinates
The circle around one of the data points is the Data Cursor. Use the arrow keys to move the Data Cursor; the left and right arrow keys step the Data Cursor to adja-cent data points, the up and down arrow keys make the cursor jump to the first and last visible data points. Press and hold the left and right arrow keys to move the cursor quickly.
The coordinate pair near the top of the Graph indicates the “X” and “Y” values of the Data Cursor.
If you have a mouse, you can move the Data Cursor by dragging it: click on the Data Cursor, hold down the mouse button, and move the mouse left and right to move the Data Cursor along the data plot.
Graph Function Keys
In the Graph, the function keys are used to change the scale and to open the Tools and Graphs menus.
F1 Autoscale
Press to make the scale of the Graph adjust automatically so that all data are visible.
F2 Scale/Move
Pressing cycles the graph through Scale mode (first press) and Move mode (second press).
F1 F2
The GLX prompts you to enter a new data run name
F1 F2
Coordinates Data Cursor
Use the arrow keys to move the Data Cursor
Jump to first point
Jump to last point
Step right to adjacent point Step left to
adjacent point
F3 F4 F1 F2
F1
F2
In Scale mode, the left and right arrow keys compress and stretch the Graph hor-izontally; the up and down arrow keys stretch and compress the Graph vertically.
In Move mode, the arrow keys make the graph move left, right, up, and down.
To return to normal mode (indicated when the function reads “Scale/
Move”), press . If the Graph is in Scale or Move mode and the arrow keys are not pressed for several seconds, the Graph will return to normal mode automati-cally.
See “Zoom” on page 21 for another way to rescale the Graph.
Scale and Move with a Mouse
If you have a mouse, you can scale and move the Graph by dragging it with the mouse cursor. (It is not necessary to press first.)
To change the scale, click and drag on (or between) the numeric labels on the edges of the Graph to change the vertical and horizontal ranges.
To move the plot up, down, left, and right, click and drag anywhere in the “back-ground” of the Graph.
To zoom in on part of the Graph, hold down while you click and drag to draw a rectangle. The area enclosed by the rectangle will enlarge to fill the screen.
F3 Tools Menu
Use the analysis tools contained in the Tools menu to obtain numerical informa-tion from the Graph (such as coordinates and statistics), to visualize different properties of the plotted data (such as slope and area), and to enlarge a selected area. This menu also contains an options to configure the Trigger (see page 20).
Scale
Mode Stretch
vertically
Compress vertically
Stretch horizontally Compress
horizontally
Move up
Move down Moveright Moveleft
ModeMove
Arrow key functions in Move and Scale modes
F2 Esc
F2
Vertical Scale Horizontal Scale
Esc
Esc
Move Zoom
When you select a tool from the Tools menu,3 a check mark ( ) appears next to it. To turn off a tool, select it from the menu again, which removes the check mark and returns the Graph to normal mode. If you have a tool turned on and you choose a different tool, the previous tool will automatically turn off.
The options in the Tools menu are described below.
Smart Tool When the Smart Tool is selected from the Tools menu, a pair of crosshairs appears on the Graph with labels indicating its coordinates. Use the left and right arrow keys to move the Smart Tool to adjacent data points. Use the up and down arrow keys to send it to the first and last visible data points. Press and hold the left or right arrow key to move the Smart Tool quickly.
If you have a mouse, you can move the Smart Tool by dragging the cir-cle at the intersection of the cross hairs left and right.
Delta Tool When the Delta Tool is selected from the Tools menu, a dashed rect-angle appears on the Graph. One corner is marked with a circle, the other is marked with a triangle. Labels on the edges of the Graph indicate the width (∆X) and height (∆Y) of the rectangle, measured from the circle to the triangle.
When you first turn on the Delta Tool, the circle and triangle appear at the same point. Press the left or right arrow a few times to separate them.
The left and right arrow keys move the triangle to adjacent data points; the up and down arrow keys send the triangle to the first and last visible data points.
Press and hold the left or right arrow key to move the triangle quickly.
If you have a mouse, you can move the triangle by dragging it left or right.
The triangle designates the active corner of the Delta Tool, which is the corner that moves when you press the arrow keys or drag it with the mouse. To make the other corner active, hold and press . The triangle and circle will swap places when you release both keys.
Note that when the cursors swap places, the signs of ∆X and ∆Y change. These values are always measured from the circle to the triangle; ∆X is the triangle’s X coordinate minus the circle’s X coordinate, ∆Y is the triangle’s Y coordinate minus the circle’s Y coordinate. You would most typically be interested in the values reported when the triangle is to the right of the circle.
3To select a tool from the Tools menu:
Keypad
1. Press to open the Tools menu.
2. Use the arrow keys to move the high-light to the desired tool and press ; or press the number on the keypad corresponding to the desired tool.
Mouse
1. Click “Tools” at the bottom of the screen to open the Tools menu.
2. Click the desired tool.
F3
Slope Tool Select the Slope Tool from the Tools menu to measure the slope of a tangent line at one point on the data plot. A pair of crosshairs marks the point at which the slope is measured. Labels on the Graph’s edges show the coordinates of the point, and the slope is displayed at the bottom of the screen.
Use the left and right arrow keys to move the Slope Tool to adjacent points. Use the up and down arrow keys to send it to the first and last points. Press and hold the left or right arrow key to move the Slope Tool quickly.
If you have a mouse, you can move the Slope Tool by dragging the circle at the intersection of the cross hairs left and right.
Statistics Select Statistics from the Tools menu to put the Graph into Statistics mode. The Graph displays the minimum, maximum, average, and standard devi-ation (σ) of the data inside the region of interest (ROI), which is indicated by a dashed box.
Statistics mode
Two cursors designate the left and right sides of the ROI. The larger cursor is the active one and can be moved with the arrow keys or mouse.4 As the active cursor moves, one side of the box moves with it.
The smaller cursor indicates the side of the ROI that does not move.
To switch the active cursor to the other side of the box, hold and press . Linear Fit When Linear Fit is selected from the Tools menu, a best-fit line is applied to the data in the ROI. (See “Statistics” above for instructions on setting the ROI.)
The slope, the Y-intercept, the mean squared error (MSE), and the root mean squared error of the linear fit are displayed at the bottom of the screen along with the correlation coefficient (r) of the data in the ROI.
Positive DX and DY Negative DX and DY
When the cursors swap places, the signs of ∆X and ∆Y change
X Y
Slope Tool
Slope Slope Tool
Statistics Region of interest
Stationary Cursor
Active Cursor
4See page 16 for detailed instructions on moving the cursor with the keypad or mouse.
Esc Õ
Region of interest
Linear Fit
( MSE)
When the Linear Fit is turned on, the special option Create Calculation from Lin-ear Fit appLin-ears in the Tools menu (see page 22).
Linear Fit can be useful even when the graphed data are not linear (qua-dratic or exponential, for instance). See “Graph Linearization” on page 47.
Area Tool Select the Area Tool from the Tools menu to measure the area between the data plot and the X-axis in the ROI. (See “Statistics” above for instructions on setting the ROI.)
For data plotted below the X-axis, the area is measured as negative. The value of area displayed at the bottom of the screen is the total area above the X-axis minus the total area below the X-axis.
Area Tool
Derivative This tool overlays a graphical representation of the derivative (or rate of change) of the data. In some cases, the Graph may need to be rescaled in order to see the overlaid derivative. The Derivative Tool is designed for titration experiments in which it is necessary to identify a point in a data set at which the maximum rate of change occurs.
Trigger The Trigger is a tool that allows you to control how the GLX collects data. With the Trigger, you make the GLX delay data recording (after you press
) until a certain condition is met by the incoming data. The Trigger has two parameters: Trigger Edge, which can be rising or falling, and Trigger Level, which specifies the data value that must be crossed. For example, on a voltage versus time graph, if you set the Trigger Edge to rising and the Trigger Level to 5 volts, data recording will not start until the measured voltage rises above 5 volts.
The Trigger can be used in normal graph mode to start continuous recording, or it can be used in Scope Mode (see page 22) to repeatedly trigger bursts of data col-lection. In both modes, the Graph must have time on the horizontal axis.
To turn on the Trigger, select it from the Tools menu.5 A horizontal dashed line appears on the Graph indicating the Trigger Level. Press the up and down arrow keys to change the Trigger Level. Press the right arrow key to cycle through ris-ing edge, fallris-ing edge, and disabled. (The Trigger is initially disabled, so you must press the right arrow key at least once to enable it.)
Positive
Area Negative
Area Total Area is area above the axis minus
area below the axis.
Trigger Level Arrow Indicating Trigger Edge
Trigger
5The Trigger turns on automatically when you turn on Scope mode. See page 22.
Increase Trigger Level
Decrease Trigger Level
Enable, Disable, and Change Trigger Edge Open Trigger
Settings
The Trigger affects data recording even if you are not viewing the Graph. If you have set up two or more triggers on separate Graph pages,6 data recording will start when the most recently set trigger condition is met.
Trigger Settings When the Trigger is turned on, you can open the Trigger Set-tings dialog box by pressing the left arrow key (you can also select it from the Tools menu). In the dialog box, use the arrow keys to highlight Trigger Enabled and press to enable or disable the Trigger. To change the edge from rising to falling, or vice-versa, use the arrow keys to highlight Trigger Edge and press
. To set the level, use the arrow keys to highlight Trigger Level, press , enter the desired value on the keypad, and press again.
You can also turn on the Stop Condition, which causes data collection to auto-matically stop at a specified time. To turn on the Stop Condition in the Trigger Settings dialog box, use the arrow keys to highlight Stop Condition and press
. When the Stop Condition is on, an icon ( ) and vertical dashed line appear on the Graph indicating the stop time. While viewing the Graph, hold down and press the left and right arrow keys to adjust the stop time. For the Stop Condition to work, the Trigger must be turned on (but does need to be enabled).
When you have finished changing the settings in the Trigger Settings dialog box, press to accept the changes, or press to cancel them.
Zoom Use the Zoom Tool to enlarge an area that you define by drawing a rect-angle. Select Zoom from the Tools menu; a zoom cursor ( ) appears. Move the cursor (using the arrow keys) to where you want one corner of the rectangle.
Press . Move the cursor to define the diagonally opposite corner of the rect-angle. Press again. The area enclosed by the rectangle enlarges to fill the screen.
If you have a mouse, you do not have to open the Tools menu to zoom.
If you have a mouse, you do not have to open the Tools menu to zoom.