Data Acquisition Idea Exchange

While running a test I developed I noticed an odd DAQmx behavior.  After a USB 6212 connection was momentarilly interupted all read and write tasks associated with the device hung until the USB cable was disconnected.  It would have been easy to code around if there was a Dev connection event and a Dev disconnection event that I could use to pause operations and trigger a Device reset.  Since the devices are PnP couldn't the DAQmx API simply make the system hardware connect/disconnect events visable?

When using a buffered counter output task, the initial delay value is not used at all.  Instead, the user specifies an array of high and low times and the first low time is used as the initial delay.

 

If the output pulse train is repeated multiple times (or continuously), the first low time represents both the time from the trigger until the first pulse as well as the time between the last pulse and the first pulse.

 

It would be desirable to decouple these parameters by allowing for the option to use Initial Delay on buffered counter output tasks (e.g. with a channel property).  Here are a couple use cases off the top of my head where Initial Delay would be very helpful (if not required):

 

1.  This is the case I ran into (posted here😞  if you want to repeat a pulse train continuously every N seconds, you have to either have that N second delay at the start of the task or use another counter as a trigger source.  Depending on high and low times you might be able to get away with writing new values to the counter on-the-fly but this isn't a universal solution.

 

2.  If you wanted to synchronize multiple continuous buffered counter output tasks (with each one sharing a fixed desired period) to a common trigger source but with a different initial delay, you would be unable to do so since the requirement of having different initial delay would affect the period of your actual signal.  You would have to compensate by tweaking the other high/low times in your waveform (giving you something that you don't really want).

Hello,

 

DaqMx Vis only works when the NI Device Loader service is running.

 

If this windows service is not running, DaqMx functions generates error like "Device not found..., undefined board, undefined hardware ...."

 

For some week, i get such an error and it take me a long time to point the real cause !

A windows or software update had changed the service startup sequence ... and the Ni device loader service was no more starting.

The solution to this problem was to configure the NI Device Loader service in order to force restart on start failure. 

 

It should be nice if daqMX functions could generate the "right error".

 

An error like : "Ni services are not running please check their current state ... The DaqMx devices could not be accessed when Ni Device Loader service is not running".

 

This problem also generates problem in MAX ! (The device treeview takes a long time to expand ... and the device autotest fail)

 

 

Thanks for kudossing this idea which could help understanding windows services problems.