BECKHOFF BK7300 - Manual (Page 18)

Basic information
14 BK7300
WD
RX
TX
Error
MODBUS
If a K-bus error occurs during operation, the procedures for reaction to a K-
bus error are executed in accordance with the parameterization. If the K-
bus error occurs during booting, the slave is not included in the data
exchange.
Fieldbus errors
WD A fieldbus error only occurs when the watchdog (WD) period has elapsed.
The watchdog is preset to 1000 ms. The WD is activated as soon as a
"write" access has been made to the coupler's process data (WD LED
goes on). After this, another "write" command must be sent to the process
data within the set WD time, in order to start the WD from zero again.
Once a WD error has occurred, data communication can only be restarted
by resetting the coupler (see "Coupler Reset", under Diagnostics).
The maximum watchdog time is 65000 ms, and it can be set by rotary
switch or via the KS2000 software.