Abstract: A programmable action sampler system (PASS) is described which holds a large number of discrete samples in a matrix of separate sample cups. The system is capable of dispensing a sample from a sample line into any one of the sample cups. At a pre-determined later time, using a cannula, the system addresses the sample from the cup for further measurement or analysis. In the preferred system, the samples flow sequentially through a tube, the liquid intermediate the samples being dispensed into a liquid waste line. The cannula between samples is bathed constantly in a wash tube, even while moving from one sample location to another. Further, in the preferred application, bacterial samples are employed, the sample cups being immersed in a constant temperature liquid bath to hold the bacterial samples at a constant incubation temperature. Among the various novel features employed in the system is a blade brake structure that accurately locates the sample head and cannula over any selected sample cup.