Siemens SINUMERIK 840D sl Function Manual page 238

Connecting sensors and actuators
8.4 Safety-related CPU-CPU communication (F_DP communication)
MD13348 $MN_SAFE_RDP_ERR_REAC: Error response
Machine data $MN_SAFE_RDP_ERR_REAC[1...n] is used to set the default alarm response,
which is initiated when an F_DP communication error occurs. The alarm response can be
dynamically changed by the appropriate user programming via system variable
$A_FRDP_ERR_REAC[1...n].
After programming the error response using the system variable, the value saved in the
machine data is no longer active until the control re-boots.
The significance of the values for the machine data correspond to the values for the system
variable $A_FRDP_ERR_REAC[1...n].
MD13349 $MN_SAFE_RDP_SUBS: Substitute values
MD $MN_SAFE_RDP_SUBS[1...n] is used to set the default substitute values that are active
after the control boots, which are output from an F_RECVDP driver to the SPL during an F_DP
communication error.
In the SPL program, the user can dynamically enter other substitute values by writing to the
system variable $A_FRDP_SUBS[1...n]. The substitute values set in the machine data are only
active again when the control reboots the next time.
Input data F_RECVDP
System variable: Error response, $A_FRDP_ERR_REAC
The response when a communication error occurs is set using the system variable
$A_FRDP_ERR_REAC[1...n]. This means, depending on the actual coupling or as a function
of the plant/system components involved in the SPL connection, the response to a
communication error, caused by an error in the communication path or by consciously
switching one of the plant/system components, can be specified. The following error responses
can be set:
● Alarm 27350 and also STOP D/E
● Alarm 27350
● Alarm 27351 (display only, self-clearing)
● No alarm is displayed.
Supplementary conditions
1. For a communication error, the following system variables are always set independent of
the error response set using the system variable $A_FRDP_ERR_REAC[1...n]:
$A_FRDP_ERROR[1...n] = 1
$A_FRDP_SUBS_ON[1...n] = 1
SPL input values $A_INSE[1...n] = $A_FRDP_SUBS[1...n]
2. When a communication error occurs, the currently programmed error response is realized.
If the error response is changed, it only becomes effective when the next communication
error occurs.
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Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated