System description
14 Function blocks for TwinSAFE logic components
2.1.2 TwinSAFE connection
Each safe communication path between the TwinSAFE logic and TwinSAFE inputs, TwinSAFE outputs or
other TwinSAFE logic terminals are referred to as TwinSAFE connection.
A communication partner is thus always the TwinSAFE master, the other the TwinSAFE slave. The
TwinSAFE logic is in a TwinSAFE connection to a TwinSAFE input or TwinSAFE output is always
TwinSAFE master. In the TwinSAFE connection to another TwinSAFE logic it may be a TwinSAFE slave.
This assignment is automatically specified by the TwinCAT System Manager, although it can also be
defined by the user.
Both the TwinSAFE master and the TwinSAFE slave have a FSoE (Safety-over-EtherCAT) address that
can be set on the respective TwinSAFE terminal via a DIP switch in order to ensure that any mix-up of the
TwinSAFE data packets is always detected. These FSoE addresses are checked within the TwinSAFE
communication and must be unambiguous in the control system. The TwinSAFE Verifier for each
TwinSAFE logic terminal checks that.
If there are several TwinSAFE logic terminals in the control system, the user must ensure that FSoE
addresses are not assigned more than once. The TwinSAFE verifier/ editor can only check one
TwinSAFE logic terminal.
For each TwinSAFE connection a watchdog time and the corresponding FSoE address for the
communication devices must be set. TwinCAT 2 offers the option of setting a SIL level, however this
setting is not supported at the moment and has no effects on the safety behavior of the system. In
another configuration option a module error (Hardware error or diagnostic message) in the TwinSAFE
communication partner can be set to trigger a communication error in the TwinSAFE group.
The EL6910/EJ6910 support activation of a ComErrAck at each connection. If this signal is connected,
the respective connection must be reset after a communication error via the signal ComErrAck, in
addition to the ErrAck of the TwinSAFE group.
Figure 2-1:Connection
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