Abstract: A two-wire transmitter is connected to two transmission lines which transmit an electric signal regarding a physical quantity detected by a sensor. The two-wire transmitter includes a current control section which controls a transmission current of the electric signal, and a starter circuit which starts at a starting time of the two-wire transmitter so that the transmission current flowing through the current control section under steady operation of the two-wire transmitter detours the current control section to flow through the starter circuit. The starter circuit stops when an output voltage of the current control section reaches a predetermined value or more after the two-wire transmitter starts.

Abstract: Since voltages of two input terminals of an output unit having an online download function are decided by voltages which are not correlative to each other, a value of an incoming current on the start-up becomes large. The present invention solves the problem of turning-on of a parasitic transistor due to a transitional minus potential even when the voltage of the output unit on a stationary state is set to 0 V in order to reduce the incoming current. In this invention, a switch is turned on and off by a download switching digital signal, and an input from a delay circuit for charging and discharging a condenser in the delay circuit whose one end is connected to a reference potential is input to one of the input terminals of the output terminal while the reference potential is applied to the other input terminal of the output unit. Thus, an input error in the output unit is reduced to prevent an excessive incoming current.

Abstract: A two-wire transmitter is connected to two transmission lines which transmit an electric signal regarding a physical quantity detected by a sensor. The two-wire transmitter includes a current control section which controls a transmission current of the electric signal, and a starter circuit which starts at a starting time of the two-wire transmitter so that the transmission current flowing through the current control section under steady operation of the two-wire transmitter detours the current control section to flow through the starter circuit. The starter circuit stops when an output voltage of the current control section reaches a predetermined value or more after the two-wire transmitter starts.

Abstract: Since voltages of two input terminals of an output unit having an online download function are decided by voltages which are not correlative to each other, a value of an incoming current on the start-up becomes large. The present invention solves the problem of turning-on of a parasitic transistor due to a transitional minus potential even when the voltage of the output unit on a stationary state is set to 0 V in order to reduce the incoming current. In this invention, a switch is turned on and off by a download switching digital signal, and an input from a delay circuit for charging and discharging a condenser in the delay circuit whose one end is connected to a reference potential is input to one of the input terminals of the output terminal while the reference potential is applied to the other input terminal of the output unit. Thus, an input error in the output unit is reduced to-prevent an excessive incoming current.