Kl1904, Kl2904 - Bus Terminals With 4 Fail-Safe Inputs Or Outputs; Kl6904 - Twinsafe Logic Terminal With 4 Fail-Safe Outputs; The Fail-Safe Principle (Fail Stop) - Beckhoff KL6904 Operating Instructions Manual

TwinSAFE digital input (KL1904) and output terminal (KL2904)
• All current safety sensors can be connected
• Operation with a TwinSAFE logic terminal
• KL1904 with 4 fail-safe inputs for sensors (24 V
• KL2904 with 4 safe channels for actuators (24 V
• Conforming to IEC 61508:2010 SIL 3
3.2.3 KL1904, KL2904 - Bus Terminals with 4 fail-safe inputs or
outputs
The KL1904 and KL2904 Bus Terminals enable connection of common safety sensors and actuators. They
are operated with the KL6904 TwinSAFE logic terminal. The TwinSAFE logic terminal is the link unit between
the TwinSAFE input and output terminals. It enables the configuration of a simple, flexible and cost-effective
decentralized safety control system.
Therefore, there are no safety requirements for the higher-level controller! The typical safety functions
required for the automation of machines, such as emergency stop, protective door, two-hand etc., are
already permanently programmed in the KL6904. The user configures the KL6904 terminal according to the
safety requirements of his application.
3.2.4

KL6904 - TwinSAFE logic terminal with 4 fail-safe outputs

The KL6904 TwinSAFE logic terminal is a digital output terminal with four fail-safe outputs with 0.5 A, 24
VDC. The KL6904 meets the requirements of IEC 61508:2010 SIL 3 and DIN EN ISO 13849-1:2006 (Cat 4,
PL e).
3.2.5

The fail-safe principle (Fail Stop)

The basic rule for a safety system such as TwinSAFE is that failure of a part, a system component or the
overall system must never lead to a dangerous condition. The safe state is always the switched off and
wattless state.
KL6904
) with floating contacts
DC
, 0.5 A per channel)
DC
Version: 3.0.0
System description
19