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Chapter
9
Operating Instructions
UE4155
52
© SICK AG • Industrial Safety Systems • Germany • All rights reserved
8010178/TF82/2010-03-05
Subject to change without notice
Fault diagnosis
9.6
System performance in the case of malfunctions in
connected devices
9.6.1
Fault with respect to the safety-related communication of FPLC
If no safety-related communication takes place to the higher-level FPLC …
the bus node switches off all outputs controlled by the FPLC;
the bus node signals an I/O error to the device connected to the SDL connection;
an error message appears on the 7-segment display of the connected SDL device
(also refer to the operating instructions of the connected device).
After the communication error to the higher-level FPLC has been fixed, the whole process
image of the bus node remains deactivated because the error status bit has been set (the
bus node is kept in a passive state)
Program an error acknowledgement!
Ensure that the FPLC program uses error acknowledgement. The FPLC program may not
acknowledge the error until it has been resolved.
The bus node automatically deletes the I/O error as soon as the FPLC acknowledges the
error. Valid I/O data are then exchanged again with the device connected to the SDL
connection.
WARNING