DataTypes

LabRAD Data Types

Overview

LabRAD data is stored together with a Type Tag describing its format. LabRAD supports several different Basic Data Types that can be combined into Composite Types and annotated by Type Modifiers.

For a formal description, refer to the EBNF LabRAD Grammar.

Basics Types

	Tag		Name		Description		Example Data
	b		Boolean		Flag		True
	i		Integer		Signed whole number		-1,500,000,000
	w		Word		Unsigned whole number		3,750,000,000
	s		String		Text		"Hello World"
	v		Value		Real number		-1.637e23
	c		Complex		Complex number		3.2 + 1.6i
	t		TimeStamp		Time and date		1/15/2006 12:53pm
	?		Any		Placeholder for any type		N/A
	__ _ __		Empty		Unspecified array type		N/A

Composite Types

	Tag		Name		Description		Example Type Tag and Data
	? or __n?__		Array		List of data with n dimensions		*s: "Karl", "Peter", "Tom"
	(...)		Cluster		Collection of data		(sw): "Karl", 27
	E or E?		Error		Error message		E: 15: "Can't divide by 0!"

Type Modifiers

	Tag		Name		Description		Example Type Tag
	[...]		Units		Units of a Value or Complex		v[GHz]
	{...}		Comment		Type tag annotation		s{Name}
	:...		End		Marks the end of the type tag		b: Turn instrument on(T)/off(F)

Examples of Valid Type Tags

	Type Tag		Example Data
	s		"Hello World"
	b {Trigger}		False
	v[m/s^2]: Acceleration		6.2
	c[ ]: Units of 1		2.8 - 6.3i
	v: No units given		-12.3e7
	(t, v[mV]) {timestamped data}		(5/17/2002 3:02:18pm, 150.1)
	*(s{name}, w{age}): members		("Karl", 27), ("Peter", 25)
	*3w {3D array of numbers}		[[[1,2,3],[4,5,6]],[[7,8,9],[10,11,12]]]
	*2_ {2D empty array of unknown type}		[[ ]]
	*2w {2D empty array of known type}		[[ ]]
	E		12, "Device unknown"
	Es		10, "Port in use", "COM3"

Examples of Invalid Type Tags

	Type Tag		Description
	g		Unknown tag
	(ws		Missing )
	w{age		Missing }
	s{no "}" here}		First } ends comment, following " is not a known tag
	w[GHz]		Only v and c can have units
	v[2]		See Units section for valid unit string
	w{frq}[GHz]		Units must follow type tag immediately; use w[GHz]{frq}
	_		Only for arrays; empty data has an empty type tag
	( ) or (_)		Clusters cannot be empty
	*		No array type specified; use __*_ __ instead
	**w		Use *2w for rectangular or *(*w) for jagged instead
	*w5		Dimensionality must immediately follow *
	*{test}5w		Dimensionality must immediately follow *
	*:w		: marks the end of the tag
	sE		E or E? must be the only tag
	Esw		Only E(sw) is allowed

 

~ Markus Ansmann, Dec 12th, 2007