Muratec MFX-2500 Field Engineering Manual page 418

Options 2-Bin/Shift Tray
(2) Shift Tray
In the Shift Tray, a photointerruptor (PWB-B2, -C2) is used. When light from the PWB-C2 LED is blocked
by a sheet of paper being fed out onto the tray, a full-of-paper condition is detected.
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