Flexability vs. Usability

I've had some family and work issues lately but I'm going to continue this blog, it makes me thinks about what's important in testing.

Lately I've been working with National Instruments PXI 6229 Multi-function I/O board and NI DAQmx drivers. Using DAQmx has made me think about flexibility versus Usability. First, DAQmx is a departure from the standard method of get a handle to a device and use it. DAQmx functions wants a DAQmx task to be created and used. The task is associated with a set of operations, whether they're Digital I/O, Analog I/O, counter operations, A/D operations, etc. The task is then started and runs however long it takes to complete or how long is specified in one of the many operations setups.

This allows the general DAQmx routines to operate on any type of board. The problem is usability. Not all boards support all operations. A Digital I/O does not support counter or clock operations. Not all operations are as clearly unfit as those. Also, it's not known whether the function will work on the board until the software is run and the function returns an error. The PXI 6229 that allows clocked operations but doesn't have a clock which disallows any "clock" DAQmx functions. (Clock operation require using the counter or an external clock on a PFI line) Things like this are not obvious. Another usability problem is that there are many clock functions and it's hard to tell which one is needed. When trying to operate the [nonexistent] clock on a 6229 it's not clear if the function itself is not usable in the situation or if the board does not support it.

The examples NI provides aren't for all boards. The examples won't run on all boards. Some of the Digital I/O examples won't run on boards with Digital I/O.

Overall, the flexibility the DAQmx functions allow inhibit the usability of the functions. NI needs to apply the KISS principle, Keep It Simple Stupid.