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If you insert a "Preserve Run-time Class" primitive on the class after casting to an LVObject it will work. Variants don't know all the intricacies of class types. So between casting the variant to a LVObject and before casting back to a variant, insert the above-mentioned primitive and away you go. Shane. I would also simply name the constant input for the Variant to Data "Object" instead of renaming the item within the variant.

Hi Alex, SUre it was a new feature in 2012 I think. The DVR is created in the RIO driver and is really intended to be fired straight into the TDMS function. The help page is at http://zone.ni.com/reference/en-XX/help/371599J-01/lvfpgahost/fpga_method_fifo_acqread/ but can't find much else. There is an example of it under Hardware Input Output>>FlexRIO>>High Throughput>>High Throughput Streaming.lvproj One thing I have never worked out is that everything references it as an "external" DVR but I never found any documentation about what this differentiation means. The one important comment is that it must be deleted before the driver can acquire more data, it must be this. Cheers, James

Just to expand.......... TDMs is a flat-file database. Basically a data table with a look-up table (by name, index etc) with no relationship between entries .MySQL, Postgres, SQLite et. al. are relational databases. A simple way to decide which is preferable for your requirements is to think about what questions you want to ask of the DB. : If you just need to look up data based on a single criteria, e.g. channel names. Then TDMS.. If you need to ask "open" questions such as "How many", "What has" or "When did". Then relational database.

Maybe use a subpanel to switch out the visible controls depending on user preference?