Change detection in PCIe 6509 in shared board

[Derek_Hopkins]

I have a situation where I have multiple applications sharing the ports of a pcie 6509.  This works correctly for static dio, However, when I set up a change detection, I can only set up on one application at a time, in spite of addressing a different port on each application.  Is this a feature or is there a way to do this?  I am interfacing using:

Daqmx 18.6

Measurement Studio

C#

Visual Studio 2017

thanks, Derek Hopkins

[croohcifer · Accepted solution]

It is expected.  There is only one change detection engine on the 6509 (and every DAQ board NI makes if I'm not mistaken).  You can see here on the list of internal signals that there's only one:

In general, accessing the same device from multiple applications is risky.  If one crashed, for example, you could leave the DAQ board in a bad state that could affect the other applications.  Is there a reason you couldn't make multiple parallel processes within the same application that each communicate with a central DAQ monitoring module?  Or perhaps have some independent DAQ application that then broadcasts state and transition information over a network protocol for other applications to consume?

[Derek_Hopkins]

yes, both of those options are possibilities and we will explore whether they give us the response time for up to 8 channels that we require.

thanks,

Derek Hopkins