BECKHOFF BK5200 - Manual (Page 11)

Basic Principles
BK52x0 11
Operating modes of the Bus Coupler
Immediately after being switched on, the Bus Coupler checks, in the
course of a “self test”, all the functions of its components and the
communication on the K-Bus. The red I/O LED blinks while this is
happening After completion of the self-test, the Bus Coupler starts to test
the attached Bus Terminals (the ”Bus Terminal Test”), and reads in the
configuration. The Bus Terminal configuration is used to generate an
internal structure list, which is not accessible from outside. In case of an
error, the Bus Coupler enters the “STOP“ state. Once the start-up has
completed without error, the Bus Coupler enters the "fieldbus start" state.
Start-up behaviour of the
Bus Coupler
Power on selftest
Bus Terminal test Structure list
The Bus Coupler reports the error to the master by means of the status
byte in the DeviceNet diagnostics (see section "Data exchange"). Clearing
the error returns the Bus Coupler to its normal operating mode.