The START pin must be set high or the START command sent to begin conversions. When START is low or if the START command has not been sent, the device does not issue a DRDY signal (conversions are halted).
When using the START opcode to control conversion, hold the START pin low. The ADS1291, ADS1292, and ADS1292R feature two modes to control conversion: continuous mode and single-shot mode. The mode is selected by SINGLE_SHOT (bit 7 of the CONFIG1 register). In multiple device configurations the START pin is used to synchronize devices (see the Multiple Device Configuration subsection of the SPI Interface section for more details).