BBH SCU Series, Installation Manual

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HB-37500-810-11-16F-EN SCU Installation Manual - Master and Slaves - SARC Page 31 of 303
Status: 09.06.2022
Man
4.1.2. Embedding into the EtherCAT network and into FSoE
4.1.2.1. FSoE data transfer
FSoE (Fail Safe over EtherCAT) is the safe data transfer via the EtherCAT network.
The application data are bundled into data packages and are additionally supplemented
with unique identifications and unique checksums.
Additionally, FSoE is monitored via timer (Watchdog). For each participant, these timers
are checked in the network. Thus, an interruption of FSoE can be safely recognized.
The checksum is calculated by means of a CRC16 (16-bit-Cycle-Redundancy-Check) and
permits to recognize errors with a residual error probability of < 10
-9 . Thus, FSoE permits
safe data transfer up to PL e or SIL 3.
Data package and CRC are transferred together (as one package) via the non-safe
EtherCAT network.
– Due to the additional calculation effort, the transfer of data package
and CRC takes place every 1ms.
4.1.2.2. EtherCAT network
The EtherCAT network consists of one Master and of a determined number of Slaves.
Data transfer takes place via Ethernet connections between the EtherCAT Master and
every participant. As a rule, these Ethernet connections are serial connctons from
participant to participant. Via these Ethernet connections, Ethernet Frames are sent. First,
every network participant must read the received data. Then, it must filter out the data
addressed to itim and insert the output data into the Frame. After the Frame has passed
all Slaves, it is sent back to the EtherCAT Master.
As thus every participant has influence on the transfer of a message, the network must be
exactly deifned, or rather, it must be specified. This specification takes place via the ESI
data. The ESI data determne the participants and their properties.