4 Safety Function Blocks
4 - 108
NX-series Safety Control Unit Instructions Reference Manual (Z931)
• This FB sends a request to change to safe mode to an actuator that has a safe mode and monitors
the status.
• S_SafetyRequest is used to send a request to change to safe mode to the actuator according to the
mode given by S_OpMode.
• The actuator returns the results of attempting to change to safe mode to S_Acknowledge.
• The FB outputs S_SafetyActive if the actuator changes to safe mode within the monitoring time
(MonitoringTime) from when the safe mode request was made.
This FB is used as an interface between the safety-related system and an actuator. This means that the
actuator’s safety-related functions can be used in the application program. However, there are only two
binary signals (the request signal and acknowledge signal) that are used to control the safe state of the
actuator.
• This safety function is provided by the actuator. Therefore, the FB only starts a request, monitors the
request, and sets an output after confirming the safe state of the actuator. This output is given by the
S_SafetyActive output.
• This FB does not define actuator-specific parameters. The parameters must be defined in the actua-
tor. The FB changes the actuator from operation mode to the safe state.
DiagCode WORD Depends on state
code.
16#0000 Refer to Safety FB Common Output Variables on page
4-4.
Function
Variable Data type Valid range Default Description
SF_SafetyRequest
Activate
S_OpMode
S_Acknowledge
BOOL
User program
Valve block
Acknowledgment
System level
SAFEBOOL
SAFEBOOL
BOOL
Ready
S_SafetyActive
S_SafetyRequest
Error
WORD
DiagCode
BOOL
SAFEBOOL
SAFEBOOL
TIME
MonitoringTime
BOOL
Reset
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