“Compact” coupler between E-bus and K-bus Terminals BK1250
I/O Error K-bus
I/O Run K-bus
Power contact
Bus Coupler
power supply
Error LED 
E-bus Link/Act LED 
Run LED 
+24 V
0 V
+24 V
0 V
Top view 
Bus Terminals
EtherCAT Terminals
extended temperature range
extended shock and vibration range

BK1250 | “Compact” coupler between E-bus and K-bus Terminals

The BK1250 is a “Bus Coupler in terminal housing” for mixed application of EtherCAT Terminals (ELxxxx) and standard Bus Terminals (KLxxxx) in a bus station. It enables implementation of compact and cost-effective control solutions. The wide range of Bus Terminals can thus be optimally combined with the communication speed and large bandwidth of EtherCAT Terminals. Up to 64 Bus Terminals (with K-bus extension up to 255) can be connected to a BK1250. The Bus Coupler recognizes the connected Bus Terminals and automatically allocates them into the EtherCAT process image.

Technical data BK1250
Number of Bus Terminals 64 (255 with K-bus extension)
Max. number of bytes fieldbus 1024 byte input and 1024 byte output
Digital peripheral signals 8,192 inputs/outputs
Analog peripheral signals 256 inputs/outputs
Protocol EtherCAT
Configuration possibility via KS2000 or EtherCAT (ADS)
Data transfer rates 100 Mbit/s
Bus interface via E-bus contacts
Power supply 24 V DC (-15 %/+20 %)
Input current 70 mA + (total K-bus current)/4, 200 mA max.
Starting current approx. 2.5 x continuous current
Recommended fuse ≤ 10 A
Current supply K-bus 500 mA
Power contacts max. 24 V DC/max. 10 A
Electrical isolation 500 V (power contact/supply voltage/Ethernet)
Weight approx. 55 g
Operating/storage temperature -25…+60 °C/-40…+85 °C
Relative humidity 95 %, no condensation
Vibration/shock resistance conforms to EN 60068-2-6/EN 60068-2-27
EMC immunity/emission conforms to EN 61000-6-2/EN 61000-6-4
Protect. class/installation pos. IP 20/variable
Approvals/markings CE, UL, ATEX
Ex marking II 3 G Ex nA IIC T4 Gc
Accessories/related products  
KS2000 configuration software for extended parameterisation
Cordsets cordsets and connectors
FC9001-0010 | FC9011 Ethernet PCI fieldbus cards
BK1120 EtherCAT “Economy plus” Bus Coupler for up to 64 Bus Terminals (255 with K-bus extension)
BK1150 EtherCAT “Compact” Bus Coupler for up to 64 Bus Terminals (255 with K-bus extension)
EtherCAT For further EtherCAT products please see the system overview.