ERES81 is a short-range transceiver (less than 1 meter) operating at a frequency of 13.56 MHz. It is a mono-block device with built-in antenna, equipped with two circular connectors. Based on inductive transmission, it dialogs with a second identical device facing it in ground/aboard data exchange applications (railway applications). Through an RS 422 serial link (8 pins connector), it sends the received data from the transceiver facing to a control equipment, and receives from it the data to be transmitted to the facing device. A second connector (19 pins) brings together the inputs/outputs TOR (all or nothing). Three to four ERES outputs can be ordered by the other ERES and conversely (to refer to the user manual). Frames preregistered and selectionnables by the inputs can also be programmed via the serial link RS 422 by means of a software tool. ERES81 can function indifferently with any or the two connected connectors.