TOTAL POWER refers simply to data acquistion without any of the other 3 fast Switching Modes. (Even in this case the same type of hardware synchronization signals is used to control the regular readout of the backends. In this case there is only one switching phase.)
Normally, when using TOTAL POWER one or several positions ``ON'' the source are observed alternating with one or several ``OFF''-source reference positions, and the signal is calculated as the difference between ``ON'' and ``OFF''.