![background image](http://html1.mh-extra.com/html/keithley/2651a/2651a_reference-manual_661729261.webp)
Model 2651A High Power System SourceMeter® Instrument Reference Manual
Section 6: Instrument programming
2651A-901-01 Rev. A / March 2011
6-17
NOTE
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
Value
Notes
"nil"
not declared
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"
true or false
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
.
"number"
number
All numbers are real numbers; there
is no distinction between integers
and floating-point numbers.
"string"
sequence of words or
characters
"function"
a block of code
Functions can carry out a task or
compute and return values.
"table"
an array
New tables are created with {}
braces. For example,
{1, 2, 3.00e0}.
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))
nil nil
Example: Boolean
y = false
print(y, type(y))
false boolean