Field device
Disclosed is a field device which determines whether or not an abnormality which was detected is the type of abnormality which may not allow the output of a burn-out H signal, and sets a signal output for the abnormality to a burn-out L signal when the type of abnormality was one which may not allow the output of a burn-out H signal. For example, an abnormality in the D/A converter or the power supply. Therefore, a burn-out L signal is always output for an abnormality judged likely not to be able to output a burn-out H signal, and the certainty of reporting an abnormality when burn-out H is set is enhanced.
1. A field device comprising:
electric current regulator regulating the value of an electric current that flows in a two-wire transmission circuit in accordance with a measured value, with a specific electric current range as a normal regulating range;
fault detector detecting various types of faults that occur within the device itself;
burnout direction setting device able to set whether to output to the transmission circuit a first burnout signal of a level higher than an upper limit value of the normal regulating level or to output to the transmission circuit a second burnout signal that is less than a lower limit value for the normal regulating range, when a fault has been detected by the fault detector;
and burnout direction changing device evaluating whether or not it is possible to output the first burnout signal in relation to a fault that has been detected by the fault detector, and causing the signal that is outputted in response to the fault to be the second burnout signal if it is determined that it is not possible to output the first burnout signal.
2. A field device as set forth in claim 1 , wherein:
the burnout direction changing device comprises:
fault type identifyer identifying, when a fault has been detected by the fault detectors, whether or not that fault is a fault of a type wherein there is a possibility that the first burnout signal cannot be outputted; and
burnout signal changing device using the second burnout signal as the signal to be outputted for the fault when a fault of a type wherein there is a possibility that the first burnout signal cannot be outputted has been identified by the fault type identifyer.
3. A field device as set forth in claim 1 , wherein:
the burnout direction changing device comprises:
burnout signal setting status checking device checking the setting status, by the burnout direction setting device, for the burnout signal when a fault has been detected by the fault detector; and
burnout signal changing device checking, when it has been confirmed, by the burnout signal setting status checking means, that the setting status is that of outputting the first burnout signal, whether or not it is actually possible to output the first burnout signal, and for using the second burnout signal as the signal that is outputted for the fault if it was not actually possible to output the first burnout signal.
4. A field device as set forth in claim 1 , set in advance statically to use the first burnout signal has the burnout signal to be outputted to the transmission circuit.