Device for coagulation and/or cutting of biological tissue comprising an apparatus and an instrument electrically connected with the apparatus, wherein the apparatus is configured to provide a supply voltage or a supply current at a first apparatus output and wherein the apparatus comprises an evaluation circuit that is configured to provide an evaluation signal at a second apparatus output, wherein an operation circuit of the instrument comprises: - a supply connector that can be connected with the first apparatus output and a signal connector that can be connected with the second apparatus output, - a control circuit connected with the signal connector that is configured to create a control signal depending on a polarity (S1, S2) of the evaluation signal and that comprises a manually operable first switch, - a switch unit that can be controlled by the control signal and that can be switched between a first switch condition and a second switch condition and that is connected with the supply connector and a cutting output, - wherein the control circuit is configured to adjust the characteristic of the evaluation signal depending on the operating condition of the first switch and wherein the evaluation circuit is configured to detect the characteristic of the evaluation signal and to adjust the polarity (S1, S2) of the evaluation signal depending on the characteristic. wherein the apparatus is configured to provide a supply voltage or a supply current at a first apparatus output and wherein the apparatus comprises an evaluation circuit that is configured to provide an evaluation signal at a second apparatus output, wherein an operation circuit of the instrument comprises: - a supply connector that can be connected with the first apparatus output and a signal connector that can be connected with the second apparatus output, - a control circuit connected with the signal connector that is configured to create a control signal depending on a polarity (S1, S2) of the evaluation signal and that comprises a manually operable first switch, - a switch unit that can be controlled by the control signal and that can be switched between a first switch condition and a second switch condition and that is connected with the supply connector and a cutting output, - wherein the control circuit is configured to adjust the characteristic of the evaluation signal depending on the operating condition of the first switch and wherein the evaluation circuit is configured to detect the characteristic of the evaluation signal and to adjust the polarity (S1, S2) of the evaluation signal depending on the characteristic. - a supply connector that can be connected with the first apparatus output and a signal connector that can be connected with the second apparatus output, - a control circuit connected with the signal connector that is configured to create a control signal depending on a polarity (S1, S2) of the evaluation signal and that comprises a manually operable first switch, - a switch unit that can be controlled by the control signal and that can be switched between a first switch condition and a second switch condition and that is connected with the supply connector and a cutting output, - wherein the control circuit is configured to adjust the characteristic of the evaluation signal depending on the operating condition of the first switch and wherein the evaluation circuit is configured to detect the characteristic of the evaluation signal and to adjust the polarity (S1, S2) of the evaluation signal depending on the characteristic.