PyVISA

The PyVISA project offers a solution to the tediousness of programming measurement instruments. With different protocols being sent over various interface and bus systems, finding libraries that support both your device and bus system for every programming language can become a real pain. However, the VISA specification was developed in the 90s to ease the unfortunate situation. Today, VISA is implemented on all significant operating systems, and many vendors offer VISA libraries. While some libraries might be limited to certain interface devices, most can work with arbitrary peripheral devices.

The VISA specification has explicit bindings to Visual Basic, C, and G (LabVIEW's graphical language). But you can also use VISA with any language capable of calling functions in a DLL. Python is one such language, and the PyVISA project is a VISA binding for Python. It relies on an external library file that you can download from your interface vendor's web pages. PyVISA implements a convenient and Pythonic access to this library in two layers.

First, there is the lower level vpp43, which directly calls the VISA functions from Python. This layer is only for those who require full control or need the official VISA functions for some reason. On top of it, an object-oriented Python module has been created called visa, which is easier and more convenient to use. The PyVISA manual contains more information.

The latest release of PyVISA addresses several issues, such as timeout errors passing silently and problems arising due to missing functions in older VISA DLLs. Overall, PyVISA is an efficient and reliable solution for working with measurement instruments, especially when using Python.