Siemens SINUMERIK 840D sl Function Manual page 238

Connecting Sensors/Actuators
7.3 Safe programmable logic (SPL)
Two acknowledge inputs Q1 and
Q2
Three timer initialization values
TI1 to TI3
One timer limit value TM1
Four output values A0 to A3
Initialization in the part program
The connections for the function block are defined when initialized. The input and
output quantities of the function block are assigned to the required system vari-
ables ($A_MARKERSI, $A_INSE, $A_OUTSE,...). The following functions must be
called:
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition
Q1 must be supplied with the signal from the real
acknowledge button.
Q2 is only used to automatically acknowledge the
safety software relay as part of the forced checking
procedure. The software relay itself does not have to
be subject to a forced checking procedure. However, if
the Emergency Stop function is executed and if exter-
nal actuators have be subject to a forced checking
procedure, if the relay drops out during the Emergency
Stop test, then it can be acknowledged using Q2 (in a
defined time window, refer to TM1). This input must
also be connected with a safety system variable (even
if the signal is not used) – preferably with a
$A_MARKERSI – in order to detect that this acknowl-
edge signal is available as steady–state signal in the
crosswise data comparison with the PLC. The associ-
ated comparison data in the PLC must have a steady–
state 0 signal level (error detection using different
states of the particular SPL marker for the PLC and
NCK).
The times after which outputs A1 to A3 are switched to
0 at a negative edge in output signal A0 are defined
here.
This limit value is used to define the maximum time
that the shutdown inputs E1 to E3 (and their AND logic
operation) may have been at a 0 signal level so that
they can still be acknowledged using Q2. This there-
fore guarantees that Q2 can only be effective as auto-
matic acknowledgment for the forced checking proce-
dure within a defined time window after the relay has
dropped out (after it has been de–energized). It is not
permissible that Q2 is used to acknowledge a "real"
shutdown.
A0 supplies the result of ANDing E1 to E3 without any
delay. Outputs A1 to A3 supply the same result for pos-
itive edges of A0; for negative edges, the results are
delayed by the timer initialization TI1 to TI3.
A0 to A3 do not produce a result after booting until an
acknowledgment has been received via Q1.
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05.08