Fail-Safe Blocks
Fail-Safe Systems
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functions may take several seconds to complete. Upon completion, the disabled F-
run-time groups will become reenabled and if the FULL_SD was TRUE indicating a
Safety Program shutdown, this output will be set to FALSE.
Note
After restarting the Safety Program, reintegration of your I/O may be necessary
through the use of the F_QUITES function block.
Note
If all Safety Programs are deleted except for the shutdown logic @F_ShutDn, the
@F_ShutDn will not be removed. This must be removed manually.
Alarm and Notify Messages
The F_SHUTDN function block generates Alarm Messages and Notify Messages
captured by an HMI (using WinCC) when a state transition occurs within the
shutdown logic. However, these messages are only reported if the F_SHUTDN
function block’s ALARM_EN input is TRUE. The state transitions are as follows:
• Full Shutdown Incoming (Alarm Message) – F_SHUTDN block entered the Full
Shutdown state either through manual request of a full shutdown or an F-Block
tripped diagnostic.
• Full Shutdown Outgoing (Alarm Message) – F_SHUTDN block exited the Full
Shutdown state because of a user requested restart.
• Partial Shutdown Incoming (Alarm Message) – If the F_SHUTDN function
block is configured with RQ_FULL set to FALSE, the first detected shutdown F-
run-time group will be alarmed as a FAILURE. While there remain shutdown F-
run-time groups, subsequent failures of this F-run-time group will not be
alarmed.
• Partial Shutdown Outgoing (Alarm Message) – F_SHUTDN block restarted the
shutdown F-run-time groups.
• Restart Incoming (Notify Message) – The user requested a restart of the
F_SHUTDN function block while it was in a full or partial shutdown state.
• Restart Outgoing (Notify Message) – The shutdown logic completed the restart
sequence.
• Safety Mode Incoming (Notify Message) – Safety Mode has been enabled
(Test Mode exited).
• Safety Mode Outgoing (Notify Message) – Safety Mode has been disabled
(Test Mode entered).
The F_SHUTDN function block calls the SFB 34 “ALARM_8 to report the Alarm
Messages and SFB 31 “NOTIFY_8P to report the Notify Messages. When an
Alarm Message is reported, the MSG_XXX outputs return the status of the
ALARM_8 SFB call. To obtain help on the ALARM_8 error outputs, obtain help for
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