error 200524

[graceg]

we are getting error 200524

write cannot be performed because the number of channels in the data does not match the number of channels in the task

when writing supply data for all channels in the task

alternatively, modify the task to contain the same number of channels as the data written

number of channels in the task:1

number of channels in data:2

Could we also get an explanation for the difference between channels and samples.  Thanks!

[RavensFan]

Channels would be each DAQ input or output.  You could acquire 1 or more inputs at a time.

Samples would be how many data values to acquire for each channel,  it could be 1, it could be millions.

[Dennis_Knutson]

And the error would be caused by passing the incorrect data type especially with the DAQ Assistant and (evil) dynamic data. In other words, you might be passing a 1D array (multiple channels/single update) when you should be passing a scalar (single channel/single sample). Or, passing a 2D array (multiple channels/multiple samples) instead of a 1D array (single channel/multiple samples).

Message Edited by Dennis Knutson on 08-20-2009 10:43 PM

[graceg]

could you further explain with actual examples what the difference is between a channel and a sample?

[Anil_Reddy]

channel is physical point on the DAQ board........Sample is a data point to be acquired or generated.........

When you are acquiring a signal using one channel,  you mention how many data points you want to acquire on that channel.

Message Edited by Anil Reddy on 08-21-2009 01:50 AM

[RavensFan]

Channels  ai0, ai1, ai2, ....

Samples,  I want to acquire 1 data point on each channel, or I want to acquire 1000 datapoints, 1 million datapoints ......

[Dennis_Knutson]

For analog output, look at the example called Gen Mult Volt Updates-Int Clk. It writes to two different channel (ai0,ai1) and it writes multiple samples to each channel - a waveform data type array with two elements (one for each channel) and each waveform contains 750 elements (the number of samples to write).