like you I like the SupportedCaps capability and enjoy using Get to determine what the appropriate values are, seems kinda natural to use the capabilities as they are documented and as they are used in sample code.
that said, if you see different values returned from a driver than are displayed on the driver’s Ui there is a good chance you are either doing something wrong, have a close to worthless driver on your hands or both.
what are you using for units and how is the tranfer set? try switching to file mode for the transfer to check the memory issue. if you have not taken a look at Dosadi’s twirl & twister utilities with that datasource.
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