ConfigureChangeDetection

[Phosfor]

Hi,
 
I want to detect the falling edges of the digital I/O's of my DAQ-card (PCI-6013).
When I write the code, I use the following command:
 
DigitalTask.Timing.ConfigureChangeDetection("", Channels, SampleQuantityMode.ContinuousSamples, 1000);
 
The string Channels has the value: "Dev1/port0/line0:7"
When this command is run, the compiler (C#) gives an error, with the following comment:
Requested value is not a supported value for this property.
Property: National Instruments.DAQmx.Timing.SampleTimingType
You Have Requested: NationalInstruments.DAQmx.SampleTimingType.ChangeDetection
You Can Select:
NationalInstruments.DAQmx.SampleTimingType.OnDemand
Task Name: _unnamedTask<5>
Status Code: -200077
 
How is this possible. The same line of code is used in the examples from NI. These exampples give the same error!
The exapmle is:
C:\Program Files\National Instruments\MeasurementStudioVS2005\DotNET\Examples\DAQmx\Digital\Read Values\
ReadDigChan_ChangeDetection\Cs\ReadDigChan_ChangeDetection.2005.sln
Please advise!
 
Kind regards...

[RikP]

Hello,
The reasson why you are seeing this error is as follows: The PCI-6013 has static digital I/O lines. This means that you can only check the value of the lines by a software call, or the other way around: you can only update output lines by a software call. The function you are using is only supported for Digital I/O boards that have hardware timed digital I/O lines.
The only way of setting up a change detection with this board is by polling a line in software and comapre its value with the previous one. This is offcourse much slower and far less deterministic as a hardware change detection. But this is the only way to do it with this board. If you realy need the changedetection functionality in hwardware you have to switch to a board that supports that functionality.
Regards,
RikP
National Instruments
 
 Message Edited by RikP on 12-19-2006 04:46 AM

[Phosfor]

Hello,
Thanks for your reply. In the mean time I found out that my board indeed doesn't support change detection.
I actually don't need a fast digital IO detection so that's no problem at all. I already have a software sollution.
So the problem is fixed already, but thanks anyway.
 
Regards,
Phosfor