Abstract: A field device has a primary power supply generating circuit that generates a primary power supply from an electric current that is supplied through a pair of electric wires from a higher-level system, and a calculation processing portion and various functional circuit portions, which operate based on a supply of an operating power supply electric current produced from the primary power supply. The field device also has an operating power supply electric current supplying unit that supplies the operating power supply electric current to a calculation processing portion with maximum priority. The calculation processing portion receives the operating power supply electric current supplied with maximum priority, clears a self-reset operation after starting up itself, and then directs sequentially, following a predetermined sequence, supply of the operating power supply electric current to each of the various functional circuit portions.

Abstract: A current control element (variable resistance element) is provided on a supply path of the current from a voltage regulator to another voltage regulator. An alarm driving circuit is provided on a branch flow path of the current from the voltage regulator to the voltage regulator. When the alarm driving circuit needs to be operated, a current control element controlling unit controls the resistance value of the current control element to branch the current flowing through the supply path to the branch flow path. In this case, the current branched to the branch flow path is set to the amount required to operate the alarm driving circuit. Since the sum of the currents is supplied to the voltage regulator and is the same as the current flowing before the alarm driving circuit is activated, there is no shortage of supplied power to a CPU.

Abstract: 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.

Abstract: A field device has a primary power supply generating circuit that generates a primary power supply from an electric current that is supplied through a pair of electric wires from a higher-level system, and a calculation processing portion and various functional circuit portions, which operate based on a supply of an operating power supply electric current produced from the primary power supply. The field device also has an operating power supply electric current supplying unit that supplies the operating power supply electric current to a calculation processing portion with maximum priority. The calculation processing portion receives the operating power supply electric current supplied with maximum priority, clears a self-reset operation after starting up itself, and then directs sequentially, following a predetermined sequence, supply of the operating power supply electric current to each of the various functional circuit portions.

Abstract: A current control element (variable resistance element) is provided on a supply path of the current from a voltage regulator to another voltage regulator. An alarm driving circuit is provided on a branch flow path of the current from the voltage regulator to the voltage regulator. When the alarm driving circuit needs to be operated, a current control element controlling unit controls the resistance value of the current control element to branch the current flowing through the supply path to the branch flow path. In this case, the current branched to the branch flow path is set to the amount required to operate the alarm driving circuit. Since the sum of the currents is supplied to the voltage regulator and is the same as the current flowing before the alarm driving circuit is activated, there is no shortage of supplied power to a CPU.

Abstract: 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.