Siemens SIMATIC PANEL PC 877 - Manual (Page 164)

Alarm, error and system messages
13.2 Introduction to the BIOS beep codes
SIMATIC Panel PC 877
13-4
Operating instructions, Release 07/2006, A5E00877780-01
Special codes
The following special code are provided in addition to the beep codes:
Special code Meaning
3x short The key is pressed during the system start: The on-board device
installation is skipped. The on-board graphic controller is used as the default
display.
1x long 8x short Error reading the MPI system information. Contact customer service.
4x short MPI-EPROM programmed for the first time.
1x long 5x short Ethernet error Contact customer service.
2x short Error in checksum test of the BIOS:
This can occur following a battery replacement or when the battery is empty.