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LabPy / lantz

Lantz is an automation and instrumentation toolkit with a clean, well-designed and consistent interface. It provides a core of commonly used functionalities for building applications that communicate with scientific instruments allowing rapid application prototyping, development and testing. Lantz benefits from Python’s extensive library flexibility as a glue language to wrap existing drivers and DLLs.
http://lantz.readthedocs.org/
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Create a driver with a different resource manager #53

Open bizarri opened 9 years ago

bizarri commented 9 years ago

I am trying to create a message based drivers using the pyvisa-py backend. I am obviously missing something, somewhere. How can I define the backend resource manager that will be used in lantz?

I tried to create a class for my driver something looking like: class LantzSignalGenerator(MessageBasedDriver): """Lantz Signal Generator. """

DEFAULTS = {'ASRL': {'read_termination': '\n', 'baud_rate': 9600}}
__resource_manager = visa.ResourceManager("@py")

.....

and I have the error: Traceback (most recent call last): File "mydriver.py", line 20, in inst = LantzSignalGenerator('ASRL/dev/ttyACM0::INSTR') File "/home/bizarri/bin/miniconda3/lib/python3.4/site-packages/lantz/messagebased.py", line 299, in init self.resource_manager = get_resource_manager() File "/home/bizarri/bin/miniconda3/lib/python3.4/site-packages/lantz/messagebased.py", line 40, in get_resource_manager _resource_manager = visa.ResourceManager() File "/home/bizarri/bin/miniconda3/lib/python3.4/site-packages/pyvisa/highlevel.py", line 1488, in __new visa_library = open_visa_library(visa_library) File "/home/bizarri/bin/miniconda3/lib/python3.4/site-packages/pyvisa/highlevel.py", line 1460, in open_visa_library return cls(argument) File "/home/bizarri/bin/miniconda3/lib/python3.4/site-packages/pyvisa/highlevel.py", line 96, in new raise OSError('Could not open VISA library:\n' + '\n'.join(errs)) OSError: Could not open VISA library:

That I interpret as the creation trying to find the "standard" ni backend (not installed).

When I directly changing the backend in Lantz messagebased.py file:

_resource_manager = None

_resource_manager = visa.ResourceManager("@py")

Everything works fine...

In the init of Lantz messagebased.py, it seems that the first thing done to look for the resource_manager via get_resource_manager() self.__resource_manager = get_resource_manager() Does it make sense??? Define like this, _resource_manager will always be None? global _resource_manager if _resource_manager is None: _resource_manager = visa.ResourceManager() return _resource_manager

I am certainly missing something trivial but unfortunately it is beyond my limited understanding of python.

Thanks in advance for your time and help.

vascotenner commented 9 years ago

I have the same issue. I would even like to have different resource managers for different drivers

vascotenner commented 7 years ago

I think this can be bypassed by setting the resourcemanager:

import lantz.messagebased as mb
mb._resource_manager = visa.ResourceManager("@py")

And then start the device.