Why does the maximum of TotalSampPerChanGenerated (output at the DAQmx Write node is double) is limited 2^32-1 on a PCI 6071E card? Where can I find an information about? On a PCI 6255 the maximum seems to be bigger.

[Stefan Heinzl]

Dear wschwab, I think I don't understand your question. The type of TotalSampPerChanGenerated is an unsigned int32. It doesn't matter with which card. (To be sure, I have simulated your two cards) The biggest number of unsigned int32 is 2^32-1. Isn`t this enough for your application? Why does this number seems bigger on an PCI-6255? best regards, Stefan Heinzl

[Werner_Schwab]

Hi Stefan,

thank you for your reply.

First, 2^32-1 on a PCI-6071E isn't enough for my application. It's a test system with an analog output sample rate of 44.100 Hz (44,1 kHz) and it should run many weeks.

Second, with all my 3 6255 cards (one PXI, two PCI) the property gives me an value greater than 2^32-1 (at this time I don't know the limit).

My disappointment is, that there is no hint in any documentation about the range the property 'TotalSampPerChanGenerated' will run on which card.

I have to implement an workaround. Ok, that's not the problem. But if the software is used with different cards, how big is the highest number before resetting to 0.

Br werner schwab

[Werner_Schwab]

Hi Stefan,

and third: The representation of the property 'TotalSampPerChanGenerated' in LabVIEW 8.5 and higher is 'Double'.

BR werner schwab

[Dennis_Knutson]

The number of samples written is NOT a dbl in LabVIEW 5.5 or higher. It is a U32

And what waveform are you be generating that requires that many points? And what connection to the waveform size is how long the test has to run? Are you under the impression that you would write that much data to the card instead of regenerating a single/small waveform?

[Werner_Schwab]

Sorry Dennis,

the output is definitely DOUBLE! Have a look at the attachment (I was not able to copy the .jpg in the message).

And otherwise, why is the right number of samples using the 6255 displayed? (after 3 weeks there is still the right number of generated samples displayed).

The period of my signal send to AO has a period of about 40s; and the amplitude may be recalculated,

Br werner schwab

[Dennis_Knutson]

I thought you were talking about the output from the DAQmx Write.It's also defined as a int32 in the DAQmx C reference,

 

I wonder if there would be difference if you just used the DAQmx Write output. With a 40 sec period, how many samples are you specifying? The  6255 also has a considerably higher sampling rate for analog out. Are you doing any error checking to see whether you have exceeded the buffer size?

Message Edited by Dennis Knutson on 03-24-2009 05:52 PM

[Werner_Schwab]

Hi Dennis,

there is a big difference.

'number of samples written per channel' shows how many samples written via DAQmx Write to the buffer (software buffer). Yes, it is possible to add them.

'TotalSampPerChanGenerated' shows how many samples written to Analog Output at this moment really.

As I use a software buffer of about 5 sec, the use of 'number of samples written per channel' ist ahead nearly 5 sec and in my application not the right choice.

Br werner schwab

[Stefan Heinzl]

Hallo Werner.

It is a known issue that some cards are having a rollover by 2^32-1.

I am sorry, but you must implement a workaround.

There are two ideas:

1. Use the Counters keep track of the samples been generated. If you dasy chain both 6255 counters, you will be able to count up to 2*(2^32-1)

2. Test when the rollover occus.

Best Regards, Stefan