Siemens SINUMERIK 840D sl Function Manual page 239

3. Whether STOP D or STOP E is initiated as error response can be parameterized using:
NCK: $MN_SAFE_SPL_STOP_MODE
PLC: DB18.DBX36.1
4. The system variable $A_FRDP_ERR_REAC[1...n] is a part of the crosswise data
comparison SPL-CDC.
Note
Until the system variable is programmed for the first time, after the control boots, the value set
using MD $MN_SAFE_RDP_ERR_REAC is active.
System variable: Substitute values, $A_FRDP_SUBS
Using the system variable $A_FRDP_SUBS[1...n], substitute values are specified, which, in
the case of an error, are output to the SPL input data parameterized using machine data
$MN_SAFE_RDP_ASSIGN. A change to the substitute values only becomes effective in the
next F_DP clock cycle - also during an error.
The system variable $A_FRDP_SUBS[1...n] is a part of the crosswise data comparison SPL-
CDC.
Note
Until the system variables are programmed for the first time, after the control boots, the values
defined using MD $MN_SAFE_RDP_SUBS[1...n] are active.
System variable: User acknowledgment, interface signal: DB18.FRDP_ACK_Rei and
channel_1 reset
A user acknowledgment is always required after a communication error detected by
F_RECVDP (system variable $A_FRDP_ERROR = 1). Once the cause of the error has been
removed and F_SENDDP and F_RECVDP are again in cyclic communication, F_RECVDP
sets the request for user acknowledgment via the system variable $A_FRDP_ACK_REI = 1.
A user acknowledgment can be realized as follows:
• PLC: Interface signal DB18.FRDP_ACK_REI
• NCK: Channel_1 reset
Driver-specific interface signal: DB18.FRDP_ACK_REI
The user acknowledgment is realized with a 0/1 change of the interface signal level. The
interface signal must either be set or reset by the PLC user program. The applies to all
F_RECVDP drivers.
Safety Integrated
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
8.4 Safety-related CPU-CPU communication (F_DP communication)
Connecting sensors and actuators
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