If you use a debugger on a C program that uses the Sensel API, set a breakpoint, and hit the breakpoint after calling a few APIs, all subsequent APIs will fail (with a "Failed to receive ack from sensor" error). I believe that any pause (due to a breakpoint or some other non-debug-related pause in the program) will cause the same failure. I noted this behavior very early on (at this no-longer-valid link):
but that issue didn't make it over to this new forum. This issue can often be worked around, but ultimately this is a pretty serious issue, since if someone ships a program that uses the API, and that program pauses after startup, for any reason, it will fail completely. I currently use a separate executable for tracking things with the Morph, and send OSC/TUIO to a second program. I would like to embed Morph support directly in the second program, but this issue prevents me from doing that.