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MCC USB-1808X Resolution in Dasylab and File Size Limit



1.  MCC USB 1808X is a 18 bit DAQ with +/-5 or +/- 10 V input.  This should give me a resolution of 38 or 76 micro Volt resolution.  Data captured via Dasylab has only 0.01 V (10 mV) resolution.  Is there some place in Dasylab where the user specifies / selects the resolution?

2.  What is the largest file size that is allowed by Files/Write Data module?  The concern is that the due to time duration of data acquisition, number of channels and sampling rate, we will exceed the 2 GB limit of 32 bit app.  Assuming a slight delay in opening a new file is acceptable, one work around could be to close the file before the file size upper limit and open a new file.  Is this feasible?  How can this be done?   

3.  I notice that Dasylab creates a blank file name on the disk for data but does not write the data until the <Stop> is executed.  How can one force Dasylab to write the data to disk as it is acquired?

Thanks much.  

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1. DASYLab uses the Double data type, so there are plenty of digits to choose from. If you're using a Digital Meter module, there is a decimals field; under Options, there's a Digits field. Set Digits to 12 and Decimals to 4. If you're writing to a CSV or Text file, there is a setting in file Options to set the number of digits per channel.

The resolution numbers you listed are theoretical. Please look at page 19 in the user manual for absolute accuracy and noise specification. 

2. The DASYLab DDF format is very efficient, and you can choose between 4-byte floats or 8-byte doubles as the data type. You could do a rough calculation of channels * data type * block size to determine how many blocks it will take to come close to the max file size. The Multi-File setup will allow switch files based on the number of blocks. 

3. DASYLab buffers files data and writes it to disk periodically. To force, there is a Save File Every setting on the Write Data module setup dialog.

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