Fault State; Backward Path - GE FVP110 Maintenance Manual

Fault State

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
Simulate Value
Transducer Status
Transducer Value
Enable/Disable
Status to be set in simulation mode.
Value to be set in simulation mode.
Status of input from transducer.
Value of input from transducer.
Whether to enable 2 or disable 1 simulation.
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AO Function Block