| 摘要 |
<p>The ticket machine includes two light emitting diodes (D1, D2) serving as indicators, each being intended to draw attention to particular anomalies in the machine operation. One diode may be red and one green, with flashing signals indicating complete failure, loss of power, printer failure etc. or just the approach of the end of the paper printing roll. The diodes are controlled by a microprocessor (10). Photodetectors (T1, T2) are arranged to detect the light signals from the LED's via optical fibres (F1, F2). These photodetectors are linked to a second microprocessor which may then be linked to a modem in order to transmit the error signals to a remote station.</p> |
