BECKHOFF BK7000 - Manual (Page 9)

Basic information
BK 7000 8
The operating modes
When it is first switched on the bus coupler carries out a self-test to check
the functions of its components and the communications of the K bus, and
while this is going on the red I/O LED will flash. When the self-test has
been completed successfully, the bus coupler will begin to test the at-
tached bus terminals (the "bus terminal test”) and read in the configuration
from which it constructs an internal structure list, which is not accessible
from outside. If an error occurs the bus coupler will enter the operating
mode "STOP”. If the start-up sequence is completed without errors the bus
coupler will enter the mode "fieldbus start”.
Start-up behavior of the bus
coupler
The bus coupler reports the error by means of the IO-ERR-LED. Clearing
the error returns the bus coupler to its normal operating mode.