An installation for processing plate-shaped substrates, especially for coating panes of glass, comprising a transport path on which the substrates to be processed are successively fed to a processing station, and a light barrier over the transport path in order to be able to control the flow of the substrates, wherein the light barrier comprises an emitter which emits a light beam over the transport path to a receiver connected to an electronic evaluation device, which is installed such that, as a result of the shading of the receiver by the substrates guided over the transport path, it generates a switching signal which indicates the presence of a substrate in the light beam, wherein the receiver has a plurality of light-sensitive cells arranged one above the other, wherein the evaluation circuit is set up such that the switching signal is emitted when more than a certain minimum number of cells is shaded.