4.2 Function Reference
The LabJack driver file is named LabJackUD.dll, and contains the functions described in this
section.
Some parameters are common to many functions:
• LJ_ERROR – A LabJack specific numeric error code. 0 means no error. (lon
32-bit integer).
• LJ_HANDLE – This value is returned by OpenLabJack, and then passed on to other
functions to identify the opened LabJack. (long, signed 32-bit integer).
To maintain compatibility with as many languages as possible, every attempt has been
keep the parameter types very basic. Also, many functions have multiple prototypes. The
declarations that follow, are written in C.
To help those unfamiliar with strings in C, these functions expect null terminated 8 bit ASCII
strings. How this translates to a particular development environment is beyond the scope
g, signed
made to
of this
documentation. A const char * is a pointer to a string that won’t be changed by the driver.
Usually this means it can simply be a constant such as “this is a string”. A char * is a pointer to
a string that will be changed. Enough bytes must be preallocated to hold the possible strings
that will be returned. Functions with char * in their declaration will have the required length of
the buffer documented below.
Pointers must be initialized in general, although null (0) can be passed for unused or unneeded
values. The pointers for GetStreamData and RawIn/RawOut requests are not optional. Arrays
and char * type strings must be initialized to the proper size before passing to the DLL.
4.2.1 ListAll()
Returns all the devices found of a given DeviceType and ConnectionType. Currently only USB
is supported.
ListAllS() is a special version where DeviceType and ConnectionType are strings rather than
longs. This is useful for passing string constants in languages that cannot include the header
file. The strings should contain the constant name as indicated in the header file (such as
“LJ_dtU3” and ”LJ_ctUSB”). The declaration for the S version of open is the same as below
except for (const char *pDeviceType, const char *pConnectionType, …).
Declaration:
LJ_ERROR _stdcall ListAll ( long DeviceType,
long ConnectionType,
long *pNumFound,
long *pSerialNumbers,
long *pIDs,
double *pAddresses)
Parameter Description:
Returns: LabJack errorcodes or 0 for no error.
Inputs:
• DeviceType – The type of LabJack to search for. Constants are in the
labjackud.h file.
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