BK7520 | SERCOS II Bus Coupler

The BK7520 Bus Coupler connects the SERCOS bus system with the electronic terminal blocks, which can be extended in modular fashion. One unit consists of one Bus Coupler, any number from 1 to 64 terminals and one end terminal. The BK7520 allows, with the K-bus extension technology, the connection of up to 255 Bus Terminals to one Bus Coupler. The Bus Coupler recognizes the connected terminals and automatically generates the affiliations of the inputs/outputs to the bytes of the process image.

SERCOS is a fiber optic bus that was developed for use in drive technology as a digital drive interface for drives. SERCOS is an open fieldbus system, which since 1995 has been subject to the international standard IEC 61491 for numerically controlled machines. It is widely used in the drive technology sector.

The bus consists of a master and of a number of slaves. In SERCOS, most of the slaves are drive amplifiers. The bus topology is a ring system, in which it is possible to operate up to 254 stations. The transmission speed is 2 and 4 Mbaud. The BK7520 supports additionally 8 and 16 Mbaud. There are basically three types of telegrams. The master SYNC telegram is received by all the slaves at the same time, and is used for synchronization. The master data telegram is also received by all the slaves, and contains the cyclic data and the service data. The slaves send their data in what is known as a drive telegram.

Parameterization can also be carried out via the SERCOS interface.

Number of Bus Terminals 64 (255 with K-bus extension)

Max. number of bytes fieldbus 254 word I/O for the cyclic interface (depending on the master)

Digital peripheral signals 1,020 inputs/outputs

Analog peripheral signals 254 inputs/outputs

Configuration possibility via KS2000

Data transfer rates 2/4/8/16 Mbaud, adjustable by means of configuration switch

Bus interface FSMA standard, IEC 872-2

Data transfer medium 1,000 µm plastic fiber optic

Power supply 24 V DC (-15 %/+20 %)

Input current 70 mA + (total K-bus current)/4, 500 mA max.

Starting current 2.5 x continuous current

Recommended fuse ≤ 10 A

Current supply K-bus 1750 mA

Power contacts max. 24 V DC/max. 10 A

Electrical isolation 500 V (power contact/supply voltage/fieldbus)

Distance between stations 40 m plastic fiber optic

Weight approx. 170 g

Operating/storage temperature 0…+55 °C/-25…+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. rating/installation pos. IP20/variable

Approvals/markings CE, UL, ATEX, IECEx

Ex marking ATEX: II 3 G Ex ec IIC T4 Gc IECEx: Ex ec IIC T4 Gc

>>> Refer to technical document: bk7520en