Siemens SINUMERIK 840D sl Function Manual page 240

Connecting sensors and actuators
8.4 Safety-related CPU-CPU communication (F_DP communication)
The driver-specific interface signals are single-channel signals and are therefore
the crosswise data comparison SPL-CDC.
Note
The user acknowledgment via the interface signal only refers to acknowledging a
communication error. If an alarm is initiated when a communication error is detected, this is
not acknowledged, and neither the alarm nor the stop responses are reset.
Channel_1 reset
The user acknowledgment is internally realized in the system by initiating the channel_1 reset
by pressing the reset key on the machine control panel
The interface signal is a single-channel signal and is therefore not part of the crosswise data
comparison SPL-CDC.
Note
If an alarm is initiated when a communication error is detected, the alarm is acknowledged,
and the alarm and stop responses are reset.
Output data F_RECVDP
System variable: Error signal, $A_FRDP_ERROR
The system variable $A_FRDP_ERROR[1...n] is used to indicate that there is a communication
error. The specific cause, determined by F_RECVDP, is communicated using the diagnostics
data (system variable $A_FRDP_DIAG[1...n]).
System variable $A_FRDP_ERROR[1...n] is cyclically compared with the corresponding PLC
variables FRDP[1...n].ERROR. If unequal, there is a system error and Alarm 27355 "F_DP:
%1 communication, connection %2 reports a system error %3 (%4)" is output.
System variable: Substitute value signal, $A_FRDP_SUBS_ON
System variable $A_FRDP_SUBS_ON[1...n] is used to signal that the substitute values,
specified using the system variable $A_FRDP_SUBS[1...n] should be output to the SPL inputs
$A_INSE[1...n].
System variable $A_FRDP_SUBS_ON[1...n] is cyclically compared with the corresponding
PLC variables FRDP[1...n].SUBS_ON. If unequal, there is a system error and this is displayed
using Alarm 27355 "F_DP: %1 communication, connection %2 reports a system error %3 (%4)".
System variable: Request signal for user acknowledgement, $A_FRDP_ACK_REQ
System variable $A_FRDP_ACK_REQ[1...n] is used to signal that after a communication error,
cyclic F-telegrams are again being exchanged, but in order to acknowledge the error and to
output the process values, a user acknowledgment is still required via the interface signal
DB18.FRDP_ACK_REI or Channel_1 reset.
System variable $A_FRDP_ACK_REQ[1...n] is cyclically compared with the corresponding
PLC variables FRDP[1...n].ACK_REQ. If unequal, there is a system error and this is displayed
using Alarm 27355 "F_DP: %1 communication, connection %2 reports a system error %3 (%4)".
240
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
not part of
Safety Integrated