PyUniversalLibrary 20061020

Release 20061020

Current version

Rewrote as a pure-Python implementation, which uses ctypes and numpy (new requirements). There is no longer a requirement on Numeric, and this should work with any reasonably backwards-compatible future versions of Python, ctypes, and numpy. The analog output examples were changed to work on USB PMD-1208FS devices.

Release 20050624

Lots of Universal Library is now covered, including all analog I/O, digital I/O, and temperature input functions.

Release 20050623

First public release.

Optional

If you intend make significant use of PyUniversalLibrary, I suggest you buy Universal Library C API. It costs $50 and includes extensive documentation and example code.

Naming conventions

‘PyUL’ is used here to mean the UniversalLibray Python module. Because UniversalLibrary is cumbersome to type, the example programs actually use “import UniversalLibrary as UL”.

PyUniversalLibrary endeavors to keep function signatures identical to the C API. These sometimes result in non-Pythonic quirks: some arguments to a function have no effect on that function because in C they are output variables. In these cases, they are returned as outputs from the function.

Error handling

The PyUL checks for errors upon every call and raises a UniversalLibraryError if an error was encountered. Instances of UniversalLibraryError have an errno attribute which can be converted to a string with a call to _get_error_message(errno).

Initialization

The short story is that importing PyUL (“import UniversalLibrary”) will do all initialization necessary.

The long story is that C programs call the cbDeclareRevision() and cbErrHandling() functions upon initialization. PyUL calls cbDeclareRevision() automatically, and calling cbErrHandling() is not needed because the default state DONTPRINT, DONTSTOP, which is exactly what PyUL expects, because PyUL checks all the error codes anyhow.