Keithley 2651A Reference Manual page 261

Model 2651A High Power System SourceMeter® Instrument Reference Manual
Do not create variable names that are the same as the base names of Model 2651A Instrument
Control Library (ICL) commands. Doing so will result in the loss of use of those commands. For
example, if you send the command digio = 5, you cannot access the digio.* commands until
the power to the instrument is turned off and then back on.
Variables can be one of the following types.
Variable types and values
Variable type returned
"nil"
"boolean"
"number"
"string"
"function"
"table"
To determine the type of a variable, you can call the type() function, as shown in the examples
below.
Example: Nil
x = nil
print(x, type(x))
Example: Boolean
y = false
print(y, type(y))
2651A-901-01 Rev. A / March 2011
NOTE
Value
not declared
true or false
number
sequence of words or
characters
a block of code
an array
nil
false
Section 6: Instrument programming
Notes
Nil is the type of the value nil,
whose main property is to be
different from any other value;
usually it represents the absence of
a useful value.
Boolean is the type of the values
false and true. In Lua, both nil
and false make a condition
false; any other value makes it
true.
All numbers are real numbers; there
is no distinction between integers
and floating-point numbers.
Functions can carry out a task or
compute and return values.
New tables are created with {}
braces. For example,
{1, 2, 3.00e0}.
nil
boolean
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