I am working with two cDAQ-9189 chassis networked together, and attempting to make use of the watchdog module on one or both to guard against possible controller and/or network failure. However, I find that the watchdog behaves inconsistently in the case of a network failure (tested by disconnecting ethernet cables while the controller is running). Approximately 60% of the time the watchdog acts as expected, but the remaining 40% of the time the watchdog does not trigger. I have tried my best to control for the initial conditions of each test, but cannot isolate the source of the inconsistency.
I am using the NI-DAQmx Python API (version 0.5.7) to control the two chassis. The problem first presented itself when the two DAQs were networked in line formation, but persists when switched to star formation (as per this page). The watchdog module performs perfectly if the code execution is abruptly stopped (simulating a controller failure), leading me to suspect that the issue comes from the DAQ chassis behaviour when the network connection is lost.
I have tried to access the 'expir_trig_trig_on_network_conn_loss' boolean stored in the watchdog task object, but when I attempt to access it I get the following error:
nidaqmx._lib.DaqFunctionNotSupportedError: The NI-DAQmx function "DAQmxGetWatchdogExpirTrigOnNetworkConnLoss" is not supported in this version of NI-DAQmx. Visit ni.com/downloads to upgrade your version of NI-DAQmx.
I have updated the base NI-DAQmx driver from the downloads page without success. As far as I can tell, version 0.5.7 is the most recent version of the Python API. Is there any way to access this functionality with the Python API, or is it impossible at this time? Does anybody have a similar experience they can share, or a potential solution to try?
