How to use method variables

Introduction

Method variables can be used to edit suitable methods. Variables can be assigned to most instruction parameters including breakpoints. Variables also form the foundation for automatic method scouting.

Each parameter defined as a variable is also assigned a default value, which is used if no changes are made to variable values at the start of a run. Up to 500 variables can be defined in a single method.

All variables are listed on the Variables tab of the Run Setup, grouped according to the block in which they appear. See The Variables tab.

Identifying variables

Parameters defined as variables can be identified in two ways:

  • In the Text pane in Text instructions, the parameter is given as the default value in parentheses followed by the variable name. The illustration below shows an example of this:

  • When the instruction is shown in the Instructions field of the Instruction box, the VAR button beside the parameter field is displayed in capital letters, that is VAR not Var.

    The illustration below shows an example of the Instruction box where UV1 and UV2 are defined as variables and the UV3 position is fixed.

When to change variable values

Variable values can be changed immediately before the start of a method run without using the Method Editor, allowing one method to be used for runs under a variety of conditions.

How to change variable values

To change default variable values, you can either

  • edit the instruction in the Instruction box

or

  • change the value in the Variables tab of Run Setup.

Changes made in the Text pane are automatically updated on the Variables tab and vice versa.

The figure below illustrates the relationship between variables in the Text pane and on the Variables tab of Run Setup:

Breakpoints or gradient lengths

If a breakpoint or gradient length is defined as a variable, changing the variable value in the Variables tab when the method run is started will shift other instruction breakpoints accordingly. This functionality is equivalent to using the Change button to alter a breakpoint or gradient length (see How to change or move method instructions for how the Change button affects instructions within gradients).

How to define new variables

Only one variable that affects block length (breakpoint or gradient length) may be defined within each block. However, any number of parameters may be defined as variables within a block. The table below describes how to define a new variable.

Step

Action

1

Select the instruction where you want to define the variable in the Text pane of Text instructions.

Result: The parameters for the instruction are shown in the Instruction box.

2

  • Locate the breakpoint or the required parameter in the Instruction box.

  • Click the Var button.

Result: The Variable Name Definition dialog box opens.

3

  • Enter a name for the variable.

  • Select the Visible in details only check box if you want to set the variable as a "details" variable. Detail variables only become visible on the Variables tab if the Show details check box is selected. This option is useful for hiding less important variables.

  • Click OK.

Result: The Var button changes to VAR to confirm the new variable. The variable is displayed in the Text pane.

Variable names

Variables are defined with names that can be explicit descriptions of the variable function, for example Sample_volume and Gradient_length. Suitable choices of variable names can make the method easier to read and understand, and also help the operator in setting variable values at the start of a method run.

The names can be up to 32 characters long and the following characters can be used:

  • Letters (A-Z)

  • Digits (0-9)

  • The underscore character (_)

The case of letters is retained, but not significant. The names Flow_Rate and FLOW_RATE are treated as identical.

How to rename a variable

The table below describes how to rename a variable:

Step

Action

1

Select the instruction that includes the variable you wish to rename in the Text pane of Text instructions.

Result: The parameters for the instruction are shown in the Instruction box.

2

  • Locate the required parameter in the Parameters field.

  • Click the VAR button.

3

Enter a new variable name in the dialog box and click OK.

Note: Variables can also be renamed in the Edit Variables dialog box in the Method Editor. See The Variables tab for more information.

How to remove a variable

The table below describes how to remove a variable by converting it into a fixed value:

Step

Action

1

In the Text pane of Text instructions, select the instruction with the variable you want to remove.

Result: The parameters for the instruction are shown in the Instruction box.

2

  • Locate the required parameter in the Parameters field.

  • Click the VAR button.

3

  • Click the Clear button to delete the variable.

  • Click OK.

Result: The VAR button changes to Var to confirm that the variable is removed.

Note: Variables can also be deleted in the Edit Variables dialog box in the Method Editor. See The Variables tab for more information.

2005-06-15