[yoyodyne]

I'm no PID expert, but the output of the PID (at least the P part) has no bearing on the dT. I think that you want to set dT long enough so that the physical system will have started to respond to the last setting and more or less leave it alone and then adjust the gains. We typically test this by running a motor at control setting X and then jump to setting Y and plot the output of the sensor providing feedback. We then set dT to the time it takes the system to reach about 60% response. There is probably a better way to determine the right value for dT but it seems to allow us to stay stable and respond reasonably fast.

Greg