BECKHOFF EL1904 - Manual (Page 15)

Product description
EL1904 13
3.2 Intended use
WARNING
Caution - Risk of injury!
TwinSAFE terminals may only be used for the purposes described below!
The TwinSAFE terminals expand the application range of Beckhoff Bus Terminal system with functions
that enable them to be used for machine safety applications. The TwinSAFE terminals are designed for
machine safety functions and directly associated industrial automation tasks. They are therefore only
approved for applications with a defined fail-safe state. This safe state is the wattless state. Fail-safety
according to the relevant standards is required.
The TwinSAFE terminals enable connection of:
 24 V
DC
sensors (EL1904) such as
emergency off pushbutton switches, pull cord switches, position switches, two-hand switches,
safety mats, light curtains, light barriers, laser scanner, etc.
 24 V
DC
actuators (EL2904) such as
contactors, protection door switches with tumbler, signal lamps, servo drives, etc.
Note
Test pulses
When selecting actuators please ensure that the EL2904 test pulses do not
lead to actuator switching or diagnostic message from the EL2904.
The following modules were developed for these tasks:
 The EL1904 terminal is an input module with digital inputs.
 The EL2904 terminal is an output module with digital outputs.
 The EL6900 terminal is a logic module.
These modules are suitable for operation with
 Beckhoff EKxxxx series Bus Couplers
 Beckhoff CXxxxx series Embedded PCs with E-bus connection
CAUTION
Follow the machinery directive
The TwinSAFE terminals may only be used in machines according to the Machinery
Directive.
CAUTION
Ensure traceability
The buyer has to ensure the traceability of the device via the serial number.