BECKHOFF EP1908 - Manual (Page 9)

Product description
EP1908-0002 7
3 Product description
3.1 EP1908-0002
The EP1908-0002 is an EtherCAT Box with digital inputs for 24 V
DC
encoders or for potential-free
contacts. The EtherCAT Box has eight fail-safe inputs.
In addition to the possibility to read potential-free contacts, the EP1908-0002 also supports the
connection of encoders with OSSD signals whose test pulse length does not exceed 350 µs and of safety
mats that operate based on the cross-circuit principle.
Frequency measurement is also supported, in order to enable standstill and speed monitoring. The
frequency below which a logical 1 is reported at the input is specified in steps of 0.1 Hz. The module
supports a minimum frequency of 2 Hz and a maximum frequency of 500Hz. Frequencies above of 500
Hz result in a diagnostic message for the module. In this case all inputs are set to safe state (logical 0).
This message can be reset through a rising edge of the safe output signal ErrAck of the EP1908-0002.
With a two-channel connection, the EP1908-0002 meets the requirements of EN 61508-1:2010 SIL 3 and
DIN EN ISO 13849-1:2006 (Cat 4, PL e).
The control voltage U
S
supplies the module electronics. The sensors are supplied from the control voltage
Up.
The TwinSAFE EtherCAT Box has the typical design of an EtherCAT Box.