VLT General Purpose I/O MCB 101, ctd. MCB 101 - Advanced I / O option, Expands the number of freely programmable, Control inputs and outputs around the following I / Os: 3 digital inputs opto-decoupled 0 - 24 V. 2 analog inputs 0 - 10 V. 2 digital outputs NPN / PNP switchable 24 V. 1 analog output 0/4 - 20 mA with reinforced coating