Agilent VISA and NI-VISA coexistence and PyVISA

Question

Is there a solution to get PyVISA to interface with an Agilent VISA library and a National Instruments VISA library from within the same python application? Agilent VISA library doesn't work with the National Instrument devices and vice-versa. I'm constrained by the hardware available to me. Running Python 2.7, PyVISA 1.4, on Win7 32 bit, Agilent GPIB, and NI Digital I/O.

I have an Agilent 82357A USB/GPIB interface and National Instruments 6534A Digital I/O instrument. I have the Agilent VISA driver installed and that works for interfacing with Agilent hardware using PyVISA but I also need to get the NI-6534 PCI Digital I/O working with National Instruments VISA.

Per the PyVISA installation document, you can define which VISA DLL file to use by creating a file called ".pyvisarc". However, you cannot switch between DLLs while the program is running. PyVISA is defined to use a Singleton design pattern (referring to vpp43.py which contains the initialization code).

Answer 1

Set them according to this diagram: