Siemens SINUMERIK 840D Description Of Functions page 158

3 Safety-Related Functions
3.10 Safe programable logic (SPL) (840D SW 4.4.18)
The criterion "commissioning phase must have been completed", is derived
from the NCK MD $MN_PREVENT_SYNACT_LOCK[0,1] in the NCK. If one of
the two field entries is not equal to 0, "commissioning phase completed" is set
internally by the crosswise data comparison. On the PLC side, this criterion is
entered using DB18.DBX36.0. If this bit is set to "1", then the commissioning
phase is considered to have been completed.
Any changes to data on the NCK and PLC side do not take effect until after
power on.
3.10.10 Direct communications between the NCK and PLC-SPL
(from SW 6.3.30)
In SPL applications, a certain degree of single-channel communications
between the two SPLs (NCK and PLC) is always required in addition to the
two-channel connection of safety-relevant switching elements. The test stop
and emergency stop acknowledgement are typical applications. There are
various ways to do this today:
1.
2.
3.
The availability of these communication paths depends on the functional scope
of the machine.
NCK
SPL
DMP-Peripherie
Fig. 3-37 Communication paths NCK-PLC
3-158
SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
The NCK and PLC are connected via external wiring
Communications via simulated NCK I/Os ($A_OUT/$A_IN; DB10)
Communications via FC21 and NCK system variables $A_DBB etc.
VDI-Nahtstelle
$A_OUT DB10.DBDxxx
$A_IN DB10.DBDxxx
FC21
$A_DBB
$A_DBW
$A_DBD
DB18.DBD128
$A_PLCSIOUT
$A_PLCSIIN DB18.DBD132
PLC
SPL
PLC-Peripherie
© Siemens AG 2003 All Rights Reserved
11.03