Python API Library Descriptions?

[mch-UT]

Looking for reference documentation for developing in python.

For example, what's the difference between BeginReadAnalogF64Request() and ReadAnalogF64Request()? They both look very similar in the hint file, but can't find any descriptions.

Thanks for help in advance!

[bkeryan]

BeginReadAnalogF64 uses "data monikers" to allow streaming data via a non-gRPC mechanism such as shared memory or RDMA, using https://github.com/ni/grpc-sideband/blob/main/README.md .

ReadAnalogF64 synchronously returns the data in the gRPC response message.

I agree this needs more documentation.

[mch-UT]

Thanks for your help, basically confirming what I feared... there's very limited documentation for python.

[bkeryan]

If you are not specifically trying to use data monikers, then take a look at the nidaqmx Python package. It supports the same API for in-process driver access and gRPC remoting.

Documentation: https://nidaqmx-python.readthedocs.io/en/stable/

Enable gRPC support by passing grpc_options= to the Task constructor.

with grpc.insecure_channel("localhost:31763") as grpc_channel:
    grpc_options = nidaqmx.GrpcSessionOptions(grpc_channel, session_name="")
    with nidaqmx.Task(grpc_options=grpc_options) as task:
        task.ai_channels.add_ai_voltage_chan("Dev1/ai0")
        ...

[mch-UT]

@bkeryan thanks for the suggestion. I did actually try this at first, but I think it won't work for my application. I'm using a local server to remotely operate a PXI, and the nidaqmx task function searches for the module on the host computer and not the target. I'm open to ideas however.

[bkeryan]

Do you mean "module" as in data acquisition device or "module" as in shared library?

If you specify grpc_options=, the nidaqmx.Task object will send requests over gRPC using the channel specified in the GrpcSessionOptions object. If you open a gRPC channel to a remote machine, you should be able to control data acquisition devices on that remote machine.

I think you should be able to load the nidaqmx package and use it with gRPC without having NI-DAQmx installed locally. It should only try to load the NI-DAQmx shared libraries when you don't specify grpc_options=. Note that in addition to the Task constructor, you also need to pass grpc_options to nidaqmx.system.System.remote() if you access the System object.

[mch-UT]

I was referring to "module" as the data acquisition device. Using the grpc_options argument in the Task object fixed the problem I was having earlier. Thanks so much for your time!