Dustin,
Thanks again for your suggestion. I'm sure your example will be useful to others, but I'm afraid it doesn't actually address my question. I guess I'm not being very clear.
The point is that I want to keep track of the values currently being sourced on my analog output channels. In my application, users can specify max and min values for the sources, which may reflect the hardware limits of the device (e.g. +/-10V in my case) or a more constrained set of software limits determined by whatever the channel is driving. If the user tries to write a value outside this range, it will be coerced and the limiting value will be sourced instead (without generating an error in this case). It is then this limiting value which should be saved in output memory, rather than the out-of-range value requested, to avoid users believing they have sourced a value they have not.
If I then allow users to choose a custom scale, then the requested values are given in scaled units, while the device max and min are still unscaled (volts). This means I need a way to convert the unscaled limits to scaled limits based on an arbitrary custom scale in order to accomplish the procedure described above. I have attached an example VI that handles linear scales only. Obviously this could be extended by adding a case structure to handle the other types of scales, but it just seemed a bit silly to me that there is no VI to accomplish this scaling already, given that it most certainly happens inside the various NI-DAQmx routines that accept custom scales.
Much of this would also be easier if it were possible to 'read back' the currently sourced value from DAQ output channels, so I wouldn't have to fake it by keeping a local memory of them, but that is a separate issue.
-Lee
