[WIP] pyVISA backend

[gribeill]

Replace NI c library backend with pure-python pyvisa-py.

Still a WIP as I occasionally get strange PyCall errors, but the basic functionality should be there. Use at your own risk!

[matthewware]

Could we write up some doc on configuring the Conda.jl environment? I'm having some issues getting this to work on some environments? I'll chat with you tomorrow.

[gribeill]

Yeah it seems to only work with some very specific combinations of python and conda. I keep getting python TypeErrors which I am very confused by... hence the WIP :)

[catosp]

Well, i tried on my work computer, but i cannot see the GPIB devices, i cannot connect to serial device:

(v1.1) pkg> add Conda
Updating registry at C:\Users\Adrian\.julia\registries\General
Updating git-repo https://github.com/JuliaRegistries/General.git
Resolving package versions...
Installed GR ─ v0.39.1
Updating C:\Users\Adrian\.julia\environments\v1.1\Project.toml
[8f4d0f93] + Conda v1.2.0
Updating C:\Users\Adrian\.julia\environments\v1.1\Manifest.toml
[28b8d3ca] ↑ GR v0.39.0 ⇒ v0.39.1
Building GR → C:\Users\Adrian\.julia\packages\GR\KGODl\deps\build.log

(v1.1) pkg> add Instruments#master
Cloning git-repo https://github.com/BBN-Q/Instruments.jl.git
Updating git-repo https://github.com/BBN-Q/Instruments.jl.git
Resolving package versions...
Updating C:\Users\Adrian\.julia\environments\v1.1\Project.toml
[2c6aeda0] ~ Instruments v0.1.0 #master (https://github.com/BBN-Q/Instruments.jl.git) ⇒ v0.1.0 #master (https://github.com/BBN-Q/Instruments.jl.git)
Updating C:\Users\Adrian\.julia\environments\v1.1\Manifest.toml
[2c6aeda0] ~ Instruments v0.1.0 #master (https://github.com/BBN-Q/Instruments.jl.git) ⇒ v0.1.0 #master (https://github.com/BBN-Q/Instruments.jl.git)
Building Instruments → C:\Users\Adrian\.julia\packages\Instruments\6mCPT\deps\build.log

julia> using Instruments
[ Info: Precompiling Instruments [2c6aeda0-45f5-11e9-10ba-f7b3d6416888]

julia> rm = ResourceManager()
0x00001001

julia> instruments = find_resources(rm)
1-element Array{String,1}:
"ASRL1::INSTR"

julia> uwSource = GenericInstrument()
GenericInstrument(0x00000000, false, 0x00000400)

julia> connect!(rm, uwSource, "ASRL1::INSTR")
ERROR: VISA C call failed with status VI_ERROR_RSRC_BUSY: The resource is valid, but VISA cannot currently access it.
Stacktrace:
[1] error(::String) at .\error.jl:33
[2] check_status(::Int32) at C:\Users\Adrian.julia\packages\Instruments\6mCPT\src\visa\VISA.jl:104
[3] #viOpen#1(::UInt32, ::UInt32, ::Function, ::UInt32, ::String) at C:\Users\Adrian.julia\packages\Instruments\6mCPT\src\visa\VISA.jl:154
[4] viOpen at C:\Users\Adrian.julia\packages\Instruments\6mCPT\src\visa\VISA.jl:153 [inlined]
[5] connect!(::UInt32, ::GenericInstrument, ::String) at C:\Users\Adrian.julia\packages\Instruments\6mCPT\src\instrument.jl:12
[6] top-level scope at none:0

julia>

[catosp]

I tried to use pyVisa-py in python 3.7 and the same results: i cannot see gpib devices.
Then i installed gpib_ctypes.
Then i added this line in python code:
from gpib_ctypes import make_default_gpib
and after this i wrote this line:
make_default_gpib()
and now i can see the gpib devices (only python) but i cannot se the usb devices.

[matthewware]

@catosp I would stick with the NI back end for now if it's working for you. We're still trying to figure out a configuration that works with all systems.