Special Measure provides a simple frontend for MATLAB's instrument control toolbox, allowing users to quickly set up flexible scans through parameter space.
Please see Installation for install instructions.
Please see the Overview page for a list of Special Measure functions, and Error Messages for a list of common error messages and what to do.
Each hardware device is represented by an instrument (not to be confused with MATLAB instrument objects) that contains information about how to control it and what channels (see below) it provides. This information roughly corresponds to the hardcoded instrument drivers and channel array in Labview SM.
The channel concept is very similar to that of Labview SM - each channel represents some parameter, input or output value of an instrument. In most cases, it will be some physical quantity. There is currently no distinction between write and read channels. All channels should support a read operation, but it is up to the user to make sure that channels that do not support write operations (typically acqusition devices) are not used as set channels. Writeable channels should always accept and return a single double, but read-only channels can also return matrices of arbitrary dimension - e.g. a vector representing a complete scan line. Writeable channels can be self ramping, in which case its variable can be ramped by the corresponding instrument. If available, this feature is always used to set channel values (function smset), and can also be used for measurements.
Information about instruments, channels (i.e. the rack) and other configuration is stored in the global struct smdata. Channels and instruments are stored in the struct array smdata.channels and smdata.inst. Major changes to smdata.inst are only required when adding new instruments or updating drivers, but it may occasionally be necessary to change certain instrument parameters, such as the data dimension for read channels.
Internally, channels and instruments are identified by their indices to the struct arrays smdata.inst and smdata.channels. These indices (printed at the beginning of each line by smprintchannels and smprintinst can also be used to specify channels and instruments in function arguments, including scan definition. Alternatively, channel and instruments names can be used. Lists of names can be given as a char arrays or cell vectors of strings. The conversion from names to indices is typically done with smchanlookup and sminstlookup. Channel names should always be unique. Instruments can be called by their instrument type identifier (smdata.inst().device, e.g. SR830) if there is only one such instrument in the rack, or an optional name, which should be unique amongst instrument types and names. Instruments with a name should generally be called by that name.
To add a channel, use the smaddchannel function. Note that depending on the instrument, further configuration may be necessary. (Particularly for channels to be ramped for data taking, or matrix-valued channels).
To remove one or several channels ch, just type "smdata.channels(ch) = [];"
Note that this will change the indices of all subsequent channels.
Use the smprintfunctions to display the most important configuration information.
The current values of all scalar channels can be displayed in figure 1001 if this figure is initialized by calling "sminitdisp". The displayed values will be updated by every call of smget and smset for each channel. To disable this feature, close figure 1001.
The measurement task to be excecuted by smrun is defined by a scan struct passed to smrun. For explanations of its fields, see scan. Note that some of the parameters are optional.