StepUp of DSAO 120 to DSAO 120A Analog Output Board DSAO 120A replaces DSAO 120 (when DSTA 170 is used) if DSTK 169 is added. DSAO 120A is galvanically isolated, DSAO 120 is not. Note! The replaced part with RMA to be returned according to T&C otherwise an extra charge will be required.