User Manual
Section 5
GFK-2958L
May 2021
Detailed Description of I/O Modules
390
5.37
Safe Feed-in Modules EP-1901, EP-1902, and
EP-1922
Figure 215: Safe
Feed-in Module EP-
1901
Figure 216: Safe Feed-in
Module EP-1902
Figure 217: Safe Feed-in
Module EP-1922
Emerson provides three variants of RSTi-EP safe feed modules EP 1901: one safe input, EP
1902: two safe inputs and EP 1922: two safe inputs, with delayed disconnection, which are
intended for connecting safety-related equipment. The RSTi-EP safe feed-input modules are
controlled using contact-based safety transducers and/or safety transducers with OSSD
(Output Signal Switching Device) inputs. The safety function consists of the safe
disconnection of 24 V outputs, the safe state of which is 24 V switched off (current path for
outputs and the OSSD output is switched off).
All input sensors are independently supplied via separate voltage paths and report the
current machine status to the control unit.
Each RSTi-EP safe feed-input module safely switches off all following modules that are
supplied by the output current path (until the next EP-7641 power module) and thus creates
a safety segment. To switch the 24 V OSSD voltage back on, either an automatic or a manual
start can be selected.
•
Automatic start: the safe output current path is switched on immediately after resetting
the safety circuit(s).