HP 2500C Series - Manual (Page 149)

Functional Overview 6-29
Firmware
Interface with Key Panel
The Key Panel consists of 3 buttons and 2 LEDs. The buttons allows you to perform
some rudimentary interactions with the firmware. The indication of the LEDs allows you
to troubleshoot any printer problems. (See Indicator Lights (Chapter 2) for more
information on the LEDs).
The firmware is running if there is AC power supply to the printer even if the printer
LEDs are off. The LEDs will light up when data is sent to the printer or when the Power
button is pressed.