How to log data at different logging rate in LabVIEW DSC

[Suki]

Is it possible to log data at different logging intervals into Citadel database using LabVIEW DSC

[Jochen]

Suki,

DSC doesn't log data periodically anyway. Instead DSC logs data on a event driven base. DSC logs data everytime a tag value changes by an amount that is higher than the log deadband value you have defined for the tag in the Tag Configuration Editor.
The data is logged with a timestamp. This data logging technique dramatically minimizes the size of logging database and improves overall system performance without loosing information. Please refer to the LabVIEW DSC User Manual for more information.

Best regards,

Jochen Klier
Application Engineering Group Leader
National Instruments Germany GmbH

[craige]

The question still remains regarding the frequency of events.....

Say I have a +-10v sin wave running at 1Hz placed into one of my input channels and I have my deadband set to 1%.  How many values will be logged into my database each second since this value is continuously changing? Will this in effect give me the sampling capability of the Citidel Database, my shared variable engine, or my cpu marriaged with some NI framework?

Something tells me that if I duplicated this signal 1000 times that the frequency of events would decrease due to CPU performance but I could be wrong. Any help on this would be appreciated.

[Aashish_M]

Hey Craige,

If you refer to Logging Data with National Instruments Citadel you find some interesting benchmarking figures with National Instruments Citadel.

"Benchmarks have demonstrated that you can write single-point data to a Citadel trace at approximately 80,000 points per second on a 3Ghz Pentium IV"

Hopefully this helps!!