S5-95F
Rules for Failsafe Operation of an S5-95F
18.17
Connecting Text Displays via the Serial Interface
In addition to programmers and SINEC L1 components, failsafe technology also allows the
interfacing of text displays to the S5-95F via the latter's serial interface.
If you have any questions about text displays, please consult your Siemens contact, who will be glad
to tell you which text displays can be connected to the S5-95F.
Safety-Related Data Areas Modifiable via Text Displays
In the safety mode, the S5-95F allows text displays to modify only
•
the parameter control DB (while the PLCs are at STOP)
•
the SINEC L1 Receive mailbox for non-failsafe data traffic
In order to ensure that the data entered in the parameter control DB cannot lead to unsafe system
states, this data must be checked for plausibility, validity and range limits in the user program. This
check routine must be run before the S5-95F processed this data.
Text displays may not be used to transfer failsafe frames to the S5-95F.
Initiating a STOP via Devices Connected to the Serial Interface
Safety Note
A STOP initiated via text displays connected to the serial interface must never be
regarded as safe, as the S5-95F could conceivably be switched to RUN via that very
device.
For this reason, switch the S5-95F off via its own switch when doing maintenance.
Conditions for Connecting Text Displays over the Serial Interface
Before interfacing the text displays, note the following carefully:
•
The text displays must be connected using shielded cables. All connections, wiring and cabling,
and cable routing must meet all EMC requirements (see section 3.4)
•
The text displays must be operated using power supply units with protective separation to DIN
VDE 0551 or EN 60742 and DIN VDE 0160
No Modification of the User Program via Text Displays
Safety Note
Modifications to the user program via text displays are not permitted, as COM 95F
cannot execute on these devices.
EWA 4NEB 812 6210-02
18-35
