Device for exchanging information between a cash register and a payment-processing device

The invention relates to a system for the processing of means of payment and a signal-processing device comprising a first data port for communication with a cash register (10). The signal-processing device (50) also comprises a second data port for communication with a display arrangement, a third data port for communication with a payment-processing device, and a buffer unit for storage of data. The device is intended, on receiving a first data quantity at the first data port, to deliver this first data quantity to a detector means for checking a first data quantity; the detector means is arranged to convey the first data quantity onwards to the buffer unit, the buffer unit is arranged to temporarily store the received data and thereafter deliver it to the second data port, the detector unit is arranged to generate a detection signal as a function of a detected final code and to deliver this detection signal to the third data port; a calculating unit is arranged to await a payment made signal from the third data port, and the calculating unit is arranged to generate an information quantity (380) as a function of receiving the payment made signal; the signal-processing arrangement is arranged to generate a second data quantity as a function of the first data quantity and of the generated information quantity générées (380), and to deliver this second data quantity to the second data port.