The KL3021 and KL3022 analog input terminals handle signals in the range from 4 to 20 mA. The current is digitised to a resolution of 12 bits and is transmitted, in an electrically isolated form, to the higher-level automation device. The input channels of the Bus Terminals have differential inputs and possess a common, internal ground potential. The KL3021 is the single-channel variant and is characterised by its fine granularity and electrical isolation. The KL3022 combines two channels in one housing. An open lead or overload condition are detected, and the terminal status is relayed to the controller via the K-bus. The run LEDs give an indication of the data exchange with the Bus Coupler. The error LEDs indicate an overload condition and a broken wire.