Siemens SINUMERIK 840D sl Function Manual page 222

Connecting Sensors/Actuators
7.3 Safe programmable logic (SPL)
Limitations and constraints
System variables $A_PLCSIOUT[1...32] and $A_PLCSIIN[1...32] are protected so
that they cannot be accessed from other programs, except the NCK-SPL program
(SAFE.SPF). A corresponding programming command is rejected with the Alarm
17070 "Channel %1 Block %2 Data write-protected".
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 03.2006 Edition
© Siemens AG, 2006. All rights reserved
03.06