User Documentation
3 System description of safe I/O modules | Sample design
9u-remote IP20 modules for functional safety manual 1484600000/07/11.2020
This chapter contains product-specic informa-
tion and notes about the use of safe I/O mod-
ules. Please also observe the system description 
in the u-remote manual (document number 
1432790000).
The u-remote system provides safe I/O modules for both 
safety protocols Safety over EtherCAT
1)
 (Fail safe over 
EtherCAT, FSOE) and PROFIsafe. Attached to a safety control 
they enable the selective switching off of plant devices.
The 4DI-4DO type as well as the 8DI type is available for 
each safety protocol. Each type is also available as type2 
variant (V2):
UR20-4DI-4DO-PN-FSOE, UR20-4DI-4DO-PN-FSOE-V2
UR20-8DI-PN-FSOE, UR20-8DI-PN-FSOE-V2
UR20-4DI-4DO-PN-FSPS, UR20-4DI-4DO-PN-FSPS-V2
UR20-8DI-PN-FSPS, UR20-8DI-PN-FSPS-V2
Both variants are identical in design, they only differ in the 
rmware and therefore in the parameters (see module de-
scriptions in Chapter5). The V2 modules enable to connect 
antivalent switching safety devices.
The V1 modules cannot be upgraded using the 
V2 rmware!
Single channel architectures (1oo1) as well as dual channel 
architectures (1oo2) can be realised with the safe inputs and 
outputs, also mixed operation is possible. In case of failure of 
the safety control the modules change into the safe status. 
X1
X2
DI
M
DI DO DIDODODO DO
FS
*
FS
*
AO DO
Safety control
Example set-up of safe I/O modules (FS
*
) in a u-remote station
1)  Safety over EtherCAT
®
 is a registered trademark and patented technology, licensed by 
Beckhoff Automation GmbH, Germany
Safety function
The information on the inputs are transferred to the safety 
control via a black channel according to EN61508-2). A safe 
input will send the input information “false” to the safety con-
trol if a signal is within the inactive range or a fault has been 
detected. 
Vice versa the information from the safety control are trans-
ferred to the outputs. The safe outputs will be deactivated if 
the output information “false” is sent from the safety control 
or a fault has been detected (safe status see technical data).
3.1  Sample design
Safe I/O modules can be placed at any position in the 
u-remote station. The only exceptions are safety segments 
built up from safe power feed modules (s. section 4.1). No 
safe I/O module with outputs (UR20-4DI-4DO-PN-FSOE or 
UR20-4DI-4DO-PN-FSPS
) may be placed within a safety 
segment.
The following picture exemplies how to design a u-remote 
station with safe I/O modules.
3  System description of safe I/O modules










