Reconnection Bug

[slartz42]

Hello,

I'm not sure if this is an issue with Windows 11 or the nidaqmx 1.2.0, but I'm having issues accessing device properties when a device is disconnected and reconnected. Specifically, I can't access the min or max analog input rates, but it may apply to all properties.

Here is some code that will reproduce the issue:

import nidaqmx
import nidaqmx.system


def test_reconnection_bug():
    # Find USB-6212
    system = nidaqmx.system.System.local()
    device = None

    for d in system.devices:
        if 'USB-6212' in d.product_type:
            device = d
            device_name = d.name
            print(f"Found {d.product_type} as {d.name}")
            break

    if not device:
        print("No USB-6212 found. Please connect one and retry.")
        return

    # Access properties - should work
    print(f"Before disconnect - Max rate: {device.ai_max_multi_chan_rate} Hz")

    input("\n>>> DISCONNECT the USB-6212 and press Enter...")
    input(">>> RECONNECT the USB-6212 and press Enter...")

    # Get completely fresh device reference after reconnection
    print("\nAfter reconnect - trying fresh device reference:")
    system = nidaqmx.system.System.local()

    for d in system.devices:
        if 'USB-6212' in d.product_type:
            print(f"Device found: {d.name}, Type: {d.product_type}")
            try:
                # This fails with error -88705 even with fresh reference
                rate = d.ai_max_multi_chan_rate
                print(f"Success: Max rate = {rate} Hz")
            except nidaqmx.errors.DaqError as e:
                print(f"ERROR: {e}")
                print(f"Error code: {e.error_code}")
            break


if __name__ == "__main__":
    print(f"nidaqmx version: {nidaqmx.__version__}")
    test_reconnection_bug()

Here is the output:

nidaqmx version: 1.2.0
Found USB-6212 as Dev1
Before disconnect - Max rate: 400000.0 Hz

>>> DISCONNECT the USB-6212 and press Enter...
>>> RECONNECT the USB-6212 and press Enter...

After reconnect - trying fresh device reference:
Device found: Dev1, Type: USB-6212
ERROR: The specified device is not present or is not active in the system. The device may not be installed on this system, may have been unplugged, or may not be installed correctly.

Device:  Dev1

Status Code: -88705
Error code: -88705

Process finished with exit code 0

System Information:

Windows 11 Home 10.0.26100
NI-DAQmx 25.5
nidaqmx-python 1.2.0
Python 3.13.6

AB#3251116

[zhindes]

I tried this with a USB-6421, and it worked fine. That is a newer device, but its also bus-powered (like the 6212). Let me see if I can find a device in that family, though...

[slartz42]

This might be specific to the older device, I just tried this with a USB-6001 and did not get an error

[zhindes]

OK - I can reproduce it on a 6212. This is an artifact of the digital architecture of that product - it has a a bus-loaded FPGA on it for controlling the hardware. It is not stored in the flash, so when DAQmx detects the device it starts the process of streaming that FPGA image down and loading it. There is a ~10s window where the device is available in the API, but we can't actually talk to it and you get those -88705 errors. Sadly there is no good way to detect when it is done aside from polling and waiting for errors like this to go away. I was also able to consistently pass with a fixed 10s wait after plugging it back in.

[slartz42]

Understood, thanks!