How to have multiple VideoMASTER devices

[DanielID]

I currently have an application that makes color bar measurements.  This VI (seen below) was quickly written just to see how well it does a color bar measurement.  One thing that I realized is that I can't programmatically select a different video analyzer.  Our test setup will actually have multiple video analyzers (PXIe-1491s) in one PXIe chassis and I will need to run VMS functions on different devices.  From what I'm seeing is that there is no way.  In case you are wondering why I just simply don't use an HDMI switch is because we are already one but we have time requirements that need us to test X amount of units per time.

[Joshua-B]

Hi DaniellD,

To change to a different device you need to first close the handles associated with the current hardware by calling the niVMS Close VI.  Next you need to specifiy which hardware you want to use by calling the niVMS Device Handles VI.  Then you need to initialize the hardware you are now going to use by calling the niVMS Initialise Devices VI.  

Hopefully this is helpful!

[DanielID]

Will this work if I'm trying to use the devices simultaneously? I'm hoping to use multiple pxie1491s at the same time. Could you provide some example code.

[DanielID]

I have attached a VI that appears to work.  The VI acquires an image from either a pxie-6545 or pxie-1491.  I can select from a PXIe-6545 or a PXIe-1491 and acquire and image.  I will next try and see what happens when I try to acquire and image from each device simultaneously.

[DanielID]

I tried the VI what I have previously posted to acquire 2 images simultaneously from a different device and I saw this error, "niMMT Manager - Handle Repository.vi, possible reason: niMMT Manager error: niMMT handle has become invalid. This could be because the first niMMT caller has stopped execution."  I get the impression that the VMS LabVIEW API can't handle simultaneous calls. 

I have attached a screenshot as well as the VI.

[Joshua-B]

Please let me know how this goes DaniellD, but I don't believe we can have simultaneous acquisitions.  The VMS VIs pull the hardware information from the configuration file Video Hardware.ini.  I don't think there is a way to specify multiple devices at once within this ini file. 

[DanielID]

I see, we were hoping to speed up our testing by having multiple video analyzers and acquiring from different HDMI sources simultaneously...