The Input/Output Box, in short IOB 4000, is an ideal addition for electromagnetic immunity test systems. With its 12 digital inputs, as many signals on one test item can be monitored. In doing so, there are two available voltage ranges; 0 V … 24 V and TTL level. There are 4 analogue inputs available which have a voltage range of 0 V … 24 V for monitoring analogue voltage values.