JPH089649Y2 - Current input type signal converter - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current input type signal converter for converting a supplied input current into an output signal of current, voltage, air pressure or the like corresponding to the current value and outputting the signal.

[0002]

2. Description of the Related Art As shown in FIG. 6, in a current input type signal converter 2, output terminals 11 and 12 of a device 1 are connected to a positive side input terminal 21 and a negative side input terminal 22, respectively.
The output terminals 24 and 25 of the current input type signal converter 2 are connected to the input terminals 31 and 32 of the other device 3. When a signal current of, for example, 4 to 20 mA whose polarity is limited is supplied from the device 1 to the current input type signal converter 2, the current input type signal converter 2 corresponds to the input current in its conversion circuit 23. , An output signal such as a current signal in another current range, a voltage signal, or an air pressure signal, and supplies the output signal to the device 3.

[0003]

In the conventional current input type signal converter, in order to check the operation of the converter 2 when it is already installed and connected, a temporary current generator is used. When supplying the input current, it is necessary to take measures such as disconnecting the wiring so that the device 1 connected to the input terminals 21 and 22 is not adversely affected, and the inspection work is complicated.

[0004]

According to the present invention, a diode is inserted in series with one of the positive side input terminal or the negative side input terminal and in the forward direction of the input current, and is opposite to the input terminal of this diode. A third terminal connected to the side is provided.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an embodiment of the present invention, in which parts corresponding to those in FIG. In this embodiment, a diode 26 is inserted between the negative side input terminal 22 and the conversion circuit 23 in series and in the forward direction. A third terminal 27 is connected to a connection point between the input terminal 22 side of the diode 26 and the conversion circuit 23 on the opposite side, and the third terminal 27 is led to the outside.

With this configuration, when the normal signal conversion operation is performed, the device 1 is connected to the input terminals 21 and 22 and the output terminals 24 and 25 are connected to the device 2 as in the conventional case. Good. When checking the operation of the current input type signal converter 2 with the devices 1 and 2 connected in this way, connect the short-circuit wire 5 between the input terminals 21 and 22 as shown in FIG. Then, the positive side output terminal 41 of the test current generator 4 is connected to the positive side input terminal 21, and the negative side output terminal 42 is connected to the third terminal 27. In this state, the output current of the device 1 passes from the output terminal 11 through the short-circuit wire 5 to the output terminal 12
Then, the signal is not supplied to the conversion circuit 23.

The current from the output terminal 41 of the current generator 4 is supplied from the terminal 21 to the conversion circuit 23, passes through the inside thereof, further passes through the third terminal 27, and returns to the output terminal 42. At this time, the action of the diode 26 does not cause a short circuit between the terminals 22 and 27. Moreover, since the terminals 11 and 12 are short-circuited by the short-circuit wire 5, the current of the current generator 4 is
There is no possibility that it will flow into the side and adversely affect the device 1. In addition,
The current generator 4 used is insulated from the device 1.
The operation of the converter 2 can be checked by varying the current generated by the current generator 4.

The output terminal 41 of the current generator 4 may be connected to the negative side input terminal 22 instead of the positive side input terminal 21.
In this case, the current from the output terminal 41 flows from the terminal 22 through the short-circuit wire 5 to the conversion circuit 23 from the terminal 21.
In the normal use state (FIG. 1), the diode 26 helps prevent backflow of current, and if an ammeter is connected between the input terminal 22 and the third terminal 27 when necessary, the input current value can be checked. can do.

As shown in FIG. 3, a diode 26 is inserted in series and in the forward direction between the positive side input terminal 21 and the conversion circuit 23, and the diode 26 and the conversion circuit 23 are connected at a third point from the connection point. The terminal 27 may be led out. In this case, when inspecting the operation of the converter 2, as shown in FIG. 4, the input terminals 21 and 22 are short-circuited by the short-circuit wire 5, and a current is generated between the third terminal 27 and the input terminal 22 (or 21). The output terminals 41 and 42 of the container 4 may be connected to each other.

Depending on the output circuit of the device 1, if the load resistance value cannot be reduced to a certain value or less, the input terminals 21 and 22 cannot be short-circuited. In this case, for example, as shown in FIG.
An empty terminal 28 is provided in the
1 and the dummy load 6 is connected to the output terminal 1 of the device 1.
1 is connected to the empty terminal 28, and the output terminal 12 is connected to the input terminal 2
2, the terminal 41 of the current generator 4 is connected to the input terminal 21, and the terminal 42 is connected to the third terminal 27. By doing so, the dummy load 6 is connected between the output terminals 11 and 12 of the device 1, the load of the device 1 is prevented from becoming zero, and the current is supplied from the current generator 4 to the converter 2. Can be inspected, and the current does not affect the device 1.

[0011]

As described above, according to the present invention, the diode is inserted in the forward direction in series with one input terminal of the current input type signal converter, and the third terminal is provided from the side opposite to the input terminal of the diode. Since the terminals are derived, the current input type signal converter can be inspected by supplying current from the current generator without disconnecting the wiring in its installed state.In that case, connect it to the converter. It is possible to prevent the device from being adversely affected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a state where the converter of the embodiment of FIG. 1 is inspected.

FIG. 3 is a block diagram showing another embodiment of the present invention.

FIG. 4 is a block diagram showing a state where the converter of the embodiment of FIG. 3 is inspected.

FIG. 5 is a block diagram showing still another embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional current input type signal converter.

Claims (1)

[Scope of utility model registration request] 1. A current input type signal converter, which is supplied with an input current and outputs an output signal according to the input current, in series with one of a positive side input terminal or a negative side input terminal to which the input current is supplied. And a diode inserted in the forward direction with respect to the input current thereof, and a third terminal connected to the side opposite to the input terminal of the diode, the current input type signal converter.