135
Fault State
AO Function Block
Fault State
As for Fieldbus-enabled positioners including the FVP110, not only a power failure but
also other errors (such as a communication error) can cause the fail-safe action. For
example, when the status of the CAS_IN input of the AO block from its upstream block
indicates a specific status, such as a communication error, the case is regarded as an
abnormality and fault state actions including a mode change are enacted.
When any of the following status exists for the moment of time specified in
FSTATE_TIME, the block goes to the fault state and the mode changes to LO mode:
❑ Target mode is Cas, and the status of CAS_IN is Bad: No Comm
❑ Target mode is Cas, and the status of CAS_IN is Good: IFS
❑ Target mode is RCas, and the status of RCAS_IN is Good: IFS
In LO mode, the block holds the output (OUT) or outputs FSTATE_VAL, according to
the setting of IO_OPTS. The factory setting is to hold the output.
Backward Path
The backward path functions as:
1. The valve position signal from the transducer block is written to the AO block
parameter READBACK.
2. Is scaled based on XD_SCALE and PV_SCALE for conversion to the process
variable PV.
3. The value of PV is fed back to the PID block or an upper-level system as the valve
position signal via the parameter BKCAL_OUT and RCAS_OUT.
If SIMULATE is set to Enable, the value of SIMULATE.Simulate_Value is always set in
READBACK.
SIMULATE contains the following data:
Simulate Status Status to be set in simulation mode.
Simulate Value Value to be set in simulation mode.
Transducer Status Status of input from transducer.
Transducer Value Value of input from transducer.
Enable/Disable Whether to enable 2 or disable 1 simulation.
To Next Page
Loading...
Need help?
General
