The VKG 420-1020 is suitable for feeding two 2-wire liquid level indicators for a current loop signal 4 ... 20 mA. The liquid level indicators are connected to terminals + 24 V and I1 resp. I2 of the VKG 420-1020. Additional SKG 420, ZKG 420 or VKG 420-1020 switching units can be integrated in the current loop (terminals I and GND). If the input value is a current 0 ... 20 mA or 4 ... 20 mA, the input terminals I and GND are to be used. If the input value is a voltage 0 ...10 V or 2 ...10 V, the input terminals U and GND are to be used. Two input channels, A and B, are available for comparison of the magnitude of two measuring signals.