Valve positioner comprising: 1.1 a housing which has a window opening; 1.2 an operating status monitoring device; 1.3 an operating status display of the operating status monitoring device, which is arranged within the housing behind the window opening; 1.4 an interface for outputting data about the operating status; wherein the valve positioner is characterized by the following features: 1.5 an adapter for wireless data transmission, in particular according to the "Bluetooth Low Energy" standard, wherein the adapter comprises the following: 1.5.1 a cylindrical housing, the radius of which is at least twice and at most ten times its height; 1.5.2 a wireless transceiver; 1.5.3 a processor which is arranged in the cylindrical housing and connected to the wireless transceiver; and 1.5.4 a data interface which is connected to the processor; 1.5.5 wherein the processor is designed to control the transceiver and the data interface and can use them to wirelessly transmit data; wherein 1.5.6 the cylindrical housing has an optical signaling device (140, 150) on a side facing away from the processor; 1.6.1 wherein the adapter is connected to the interface in order to receive data about the operating status via the interface and, in response to the receipt of these data, to control the optical signaling device to emit a predetermined optical signal; and 1.6.2 wherein the adapter is positioned between the operating status display and the window opening in a position which allows the signaling device to be inspected through the window opening. 1.1 a housing which has a window opening; 1.2 an operating status monitoring device; 1.3 an operating status display of the operating status monitoring device, which is arranged within the housing behind the window opening; 1.4 an interface for outputting data about the operating status; wherein the valve positioner is characterized by the following features: 1.5 an adapter for wireless data transmission, in particular according to the "Bluetooth Low Energy" standard, wherein the adapter comprises the following: 1.5.1 a cylindrical housing, the radius of which is at least twice and at most ten times its height; 1.5.2 a wireless transceiver; 1.5.3 a processor which is arranged in the cylindrical housing and connected to the wireless transceiver; and 1.5.4 a data interface which is connected to the processor; 1.5.5 wherein the processor is designed to control the transceiver and the data interface and can use them to wirelessly transmit data; wherein 1.5.6 the cylindrical housing has an optical signaling device (140, 150) on a side facing away from the processor; 1.6.1 wherein the adapter is connected to the interface in order to receive data about the operating status via the interface and, in response to the receipt of these data, to control the optical signaling device to emit a predetermined optical signal; and 1.6.2 wherein the adapter is positioned between the operating status display and the window opening in a position which allows the signaling device to be inspected through the window opening. 1.5.1 a cylindrical housing, the radius of which is at least twice and at most ten times its height; 1.5.2 a wireless transceiver; 1.5.3 a processor which is arranged in the cylindrical housing and connected to the wireless transceiver; and 1.5.4 a data interface which is connected to the processor; 1.5.5 wherein the processor is designed to control the transceiver and the data interface and can use them to wirelessly transmit data; wherein 1.5.6 the cylindrical housing has an optical signaling device (140, 150) on a side facing away from the processor; 1.6.1 wherein the adapter is connected to the interface in order to receive data about the operating status via the interface and, in response to the receipt of these data, to control the optical signaling device to emit a predetermined optical signal; and 1.6.2 wherein the adapter is positioned between the operating status display and the window opening in a position which allows the signaling device to be inspected through the window opening.