Siemens SINUMERIK 840D sl Function Manual page 519

System variables $A_PLCSIOUT[1..96]
Single-channel direct communication between NCK and PLC-SPL. Signals can be read by the
PLC and read and written by the NCK.
System variable $AC_SAFE_SYNA_MEM
Variable $AC_SAFE_SYNA_MEM contains the number of free synchronizing action elements
Safety Integrated. The number before and after SAFE.SPF has run is read in order to determine
the value of the required elements. The difference between the two values is then the number
that (with a safety margin) must be entered into machine data
$MC_MM_NUM_SAFE_SYNC_ELEMENTS.
System variable $A_FSDP_ERR_REAC
The response when a communication error occurs is set using the system variable. Depending
on the actual interdependency of the two plant/system components involved, the response to
a communication error, caused by a communication path error or by consciously switching off
one the plant/system components can be specifically entered.
0 = Alarm 27350 + Stop D/E
1 = Alarm 27350
2 = Alarm 27351 (only display, self-clearing)
3 = no system response
Note
The user interface is set in all cases:
$A_FSDP_ERROR = 1
$A_FSDP_SUBS_ON = 1
$A_FSDP_DIAG corresponding to the detected communication error
Whether initiated as fault response STOP D or STOP E, can be parameterized using:
NCK: $MN_SAFE_SPL_STOP_MODE
PLC: DB18.DBX36.1
Default value: After the control boots, initially, the values saved in MD
$MN_SAFE_SDP_ERR_REAC become active.
System variable $A_FSDP_ERROR
The system variable is used to indicate that there is a communication error. The error cause
determined by F_SENDDP is contained in the diagnostics data $A_FSDP_DIAG.
0 = normal operation
1 = communication error
Safety Integrated
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Data descriptions
9.7 System variable
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