We discuss properties of a cross junction composed of active areas, in which the Belousov-Zhabotinsky reaction proceeds, and passive stripes. The response of such a junction with respect to pulses of excitation arriving from perpendicular directions is studied. It is shown that the device works as a coincidence detector because the second pulse is stopped if it arrives earlier than a certain characteristic time after the first one. Using the Rovinsky-Zhabotinsky model, we calculate the size of the cross junction and specify its temporal characteristics. We suggest how the cross junction can work as a switch of a chemical signal.