Fail-Safe Modules   
7.8 1 F-RO DC24V/AC24..230V/5A Digital Electronic Module 
  ET 200S Distributed I/O System - Fail-Safe Modules 
184  Installation and Operating Manual, 08/2008, A5E00103686-07 
If the 24 VDC control voltage falls below the required value for relay pick-up or the wire to 
the input connections breaks, the relays will be released and "0" will be read back instead of 
"1." This fault is only detected if the control voltage is switched on. 
The value "1" is read back from the module if one of the two relays gets stuck (NO contacts 
remain closed). The fault is detected by comparing this readback value with the expected 
value "0" in the safety program. This fault is only detected if the control voltage is switched 
off. 
 
 
Note 
SIL3/Category 4/PLe requires the readback of process states and at least daily signal 
transitions. 
 
7.8.4  Diagnostic functions of EM 1 F-RO DC24V/AC24..230V/5A 
Output status display 
Behavior of the output status display at the F-RO module: 
●  Relay not activated: LED is not lit 
●  Relay is activated: LED is lit 
●  Relay not activated and relay contact welded: LED is lit 
Causes of Faults and Corrective Measures 
In S7 Distributed Safety F-systems you can run diagnostics by evaluating output "DIAG" of 
FB 216 "F_FDBACK" when using this F-application block in your safety program to read 
back the relay contacts (refer to the 
S7 Distributed Safety, Configuring and Programming
 
manual). 
7.8.5  Technical specifications of the EM 1 F-RO DC24V/AC24..230V/5A 
Overview 
 
Technical Specifications 
Dimensions and Weight 
Dimensions W x H x D (mm)  30 x 81 x 52 
Weight  Approx. 90 g 
Data for Specific Module 
Number of outputs   
•  Relay outputs 
1 (2 channels) 
Assigned address area