JP2009055656A - Inverter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate connection of a switch means and a load with terminals by decreasing the number of terminals for inputting/outputting the digital signal as much as possible. <P>SOLUTION: Switches 6 and 34 are interlocked to operate according to a selected input form, and switches 15 and 37 are interlocked to operate according to a selected output form. When a source input form is selected, a current route leading from a power source wire 9 to a switch 34, a common terminal 33, a contact 18, an input terminal 3, a switch 6 and a signal input circuit 7 is formed and when a sink input form is selected, a current route leading from a signal input circuit 8 to the switch 6, the input terminal 3, the contact 18, the common terminal 33, the switch 34, and a power source wire 10 is formed and a digital signal is inputted according to the open/close state of the contact 18. It is similar when a source output form or a sink output form is selected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inverter device including an input circuit capable of inputting a digital signal in a source input format and a sink input format, and an inverter device including an output circuit capable of outputting a digital signal in a source output format and a sink output format.

  The inverter device is used alone or incorporated in a host control device. In this case, in order to give an operation command to the inverter device and to obtain an operation state from the inverter device, the inverter device has a large number of input terminals and output terminals. A contact input terminal is a terminal for inputting a digital signal according to the switch means connected to the outside, for example, the contact or logic ON / OFF state. Forward / reverse operation command, operation preparation command, multistage speed command, DC braking command, reset Commands and other signals are input. The contact output terminal is a terminal that outputs a digital signal to an externally connected load such as a relay coil or logic, and is a frequency lower limit (upper limit) limit signal, low speed detection signal, specified speed arrival signal, trip signal, A load detection signal is output.

  The digital signal input format is configured so that current flows out to externally connected contacts, etc., and the source input format that inputs digital signals depending on the presence or absence of the return current, and the return current from the contacts etc. There is a sink input format in which a digital signal is input depending on the presence or absence of a flowing current to the contact or the like. Similarly, for the digital signal output format, a source output format that outputs a digital signal by flowing current to an externally connected relay coil, etc., and a sink that outputs a digital signal by sinking current from the relay coil, etc. There is an output format.

In order to reduce the number of manufacturing models, inverter manufacturers manufacture an inverter device that includes a switch for switching between the source format and the sink format and is configured to be usable in both formats. For example, the inverter device described in Patent Document 1 includes a switch that switches between a connection state in which an input terminal is pulled up and a connection state in which a pull-down is performed, and determines a sink input format and a source input format based on the switch switching state. In addition, an interface circuit that inverts the input signal or outputs it to the microcomputer in a non-inverted state according to the determination result is provided. This interface circuit further has a function of switching between the sync output format and the source output format based on the determination result.
JP-A-11-161391

  FIG. 7 shows a schematic configuration of a digital input / output circuit included in a conventional inverter device including the inverter device described in Patent Document 1. The digital input circuit 2 of the inverter device 1 includes a source input type common terminal 4 and a sink input type common terminal 5 in addition to a plurality of input terminals 3 (only one is shown in the figure). The input terminal 3 is connected to either a source input type signal input circuit 7 or a sink input type signal input circuit 8 via a switch 6, and the common terminals 4 and 5 are respectively connected to power supply lines. 9, 10 (24V, 0V).

  Similarly, the digital output circuit 11 includes a common terminal 13 for a source output format and a common terminal 14 for a sink output format in addition to a plurality of output terminals 12 (only one is shown in the figure). The output terminal 12 is connected to either the source output type signal output circuit 16 or the sink output type signal output circuit 17 via the switch 15, and the common terminals 13 and 14 are connected to the common terminals 13 and 14, respectively. Connected to power supply lines 10 and 9.

  However, in this configuration, two common terminals 4 and 5 and common terminals 13 and 14 are required for the input circuit 2 and the output circuit 11, respectively. Therefore, the number of terminals is increased and miniaturization of the inverter device 1 is prevented. Further, the source input type contact 18 must be connected between the terminals 3-4 as indicated by the solid line, and the sink input type contact 19 must be connected between the terminals 3-5 as indicated by the broken line. The output type relay coil 20 needs to be connected between the terminals 12-13 as shown by a solid line, and the sink output type relay coil 21 needs to be connected between the terminals 12-14 as shown by a broken line. As described above, since the external connection is different between the source format and the sink format, there is a possibility that the connection becomes complicated and erroneous connection occurs.

  The present invention has been made in view of the above circumstances, and its purpose is to reduce the number of terminals for inputting and outputting digital signals as much as possible and to facilitate the connection of switch means and loads to the terminals. An object of the present invention is to provide an inverter device including a circuit.

  In order to achieve the above object, the inverter device according to claim 1 is an inverter device capable of inputting a digital signal according to an open / close state of a switch means connected to the outside in a source input format and a sink input format. The input terminal to which one end of each means is connected, the common terminal to which the other end of each switch means is connected in common, and the common terminal corresponding to the first common potential corresponding to the source input format and the sink input format First switching means connected to any one of the second common potentials, and first and second input circuits provided for each of the input terminals for inputting digital signals of the source input format and the sink input format, respectively. In conjunction with the first switching means, the input terminal is connected to one of the first and second input circuits according to each input format. Characterized in that it comprises a second switching means.

  According to this configuration, if each switch means is connected between each input terminal and a common common terminal regardless of the input format, the first and second switching means are interlocked. The common terminal is connected to the first common potential and the input terminal is connected to the first input circuit, so that a signal can be input in the source input format. On the other hand, when switching to the sink input format, the common terminal is connected to the second common potential and the input terminal is connected to the second input circuit, so that signals can be input in the sink input format.

  The inverter device according to claim 2, wherein the inverter device is capable of outputting a digital signal in a source output format and a sink output format to a load connected to the outside, and an output terminal to which one end of each load is connected, A common terminal to which the other ends of the loads are connected in common, and a first terminal for connecting the common terminal to either the first common potential corresponding to the source output format or the second common potential corresponding to the sink output format. Switching means, first and second output circuits provided for each of the output terminals for outputting digital signals in a source output format and a sink output format, respectively, and in conjunction with the first switching means, the output And a second switching means for connecting the output terminal to one of the first and second output circuits according to the type.

  According to this configuration, if each load is connected between each output terminal and a common common terminal regardless of the output format, the first and second switching means work together, so when switching to the source output format, The common terminal is connected to the first common potential and the output terminal is connected to the first output circuit, so that a signal can be output in the source output format. On the other hand, when switching to the sink output format, the common terminal is connected to the second common potential and the output terminal is connected to the second output circuit, so that a signal can be output in the sink output format.

  According to the inverter device of the present invention, since common terminals can be shared, the number of terminals for inputting and outputting digital signals can be reduced as much as possible. Further, it is not necessary to change the switch means or the terminal for connecting the load in accordance with the input format or the output format, so that the connection is facilitated.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a schematic configuration of a digital input / output circuit built in the inverter device, and the same parts as those in FIG. The digital input circuit 32 of the inverter device 31 can input switch means connected to the outside, for example, a digital signal corresponding to the on / off state of the contact 18 in a source input format and a sink input format. The input digital signal is a plurality of signals such as a forward / reverse operation command, an operation preparation command, a multistage speed command, a DC braking command, a reset command, and the like. The inverter device 31 includes a plurality of input terminals 3 (only one is shown in FIG. 1) to which one ends of a plurality of contacts 18 (only one is shown in FIG. 1) are respectively connected, and the other ends of the plurality of contacts 18 are And a common terminal 33 connected in common.

  Each input terminal 3 is connected via a switch 6 (corresponding to the second switching means) to a signal input circuit 7 (corresponding to the first input circuit) of the source input format and a signal input circuit 8 (second filter) of the sink input format. To the input circuit). The switch 6 and the signal input circuits 7 and 8 are provided for each input terminal 3. On the other hand, the common terminal 33 is connected to one of the power lines 9 and 10 via a switch 34 (corresponding to the first switching means). The power supply line 9 has a potential of Vd (24 V) that is a first common potential corresponding to the source input format, and the power supply line 10 has a potential of 0 V that is a second common potential corresponding to the sink input format. Have. The switch 6 and the switch 34 are switched in conjunction with each other by a source input format or sink input format selection operation by the user.

  The digital output circuit 35 of the inverter device 31 can output a digital signal in a source output format and a sink output format to a load connected to the outside, for example, the relay coil 20. The digital signal to be output is, for example, a plurality of signals such as a frequency lower limit (upper limit) limit signal, a low speed detection signal, a designated speed arrival signal, a trip signal, and an overload detection signal. The inverter device 31 includes a plurality of output terminals 12 (only one is shown in FIG. 1) to which one ends of a plurality of relay coils 20 (only one is shown in FIG. 1) are connected, and other than these relay coils 20. And a common terminal 36 whose ends are commonly connected.

  Each output terminal 12 has a source output type signal output circuit 16 (corresponding to the first output circuit) and a sink output type signal output circuit 17 (second output) via a switch 15 (corresponding to the second switching means), respectively. To the output circuit). The switch 15 and the signal output circuits 16 and 17 are provided for each output terminal 12. On the other hand, the common terminal 36 is connected to one of the power supply lines 10 and 9 via a switch 37 (corresponding to the first switching means). The power supply line 10 has a first common potential corresponding to the source output format, and the power supply line 9 has a second common potential corresponding to the sink output format. The switch 15 and the switch 37 are switched in conjunction with each other by a selection operation of the source output format or the sink output format by the user. The switches 6 and 34 and the switches 15 and 37 described above are not limited to mechanical switches and may be analog switches.

  According to this configuration, in the digital input circuit 32, the contact 18 that is a switch means can be connected between each input terminal 3 and the common terminal 33 regardless of the input format. When the switches 6 and 34 are switched to the source input format side in conjunction with each other, a current path is formed from the power line 9 to the signal input circuit 7 via the switch 34, the common terminal 33, the contact 18, the input terminal 3, and the switch 6. Thus, a digital signal can be input in a source input format according to the on / off state of the contact 18. When the switches 6 and 34 are switched to the sink input format side in conjunction with each other, the current path from the signal input circuit 8 to the power supply line 10 via the switch 6, the input terminal 3, the contact 18, the common terminal 33, and the switch 34. And a digital signal can be input in a sink input format according to the on / off state of the contact 18.

  Similarly, in the digital output circuit 35, the relay coil 20 as a load can be connected between each output terminal 12 and the common terminal 36 regardless of the output format. When the switches 15 and 37 are interlocked and switched to the source output format side, a current path from the signal output circuit 16 to the power supply line 10 via the switch 15, the output terminal 12, the relay coil 20, the common terminal 36, and the switch 37 is established. The digital signal can be output from the signal output circuit 16 to the relay coil 20 in the source output format. Further, when the switches 15 and 37 are switched to the sink output format side in conjunction with each other, the current from the power line 9 to the signal output circuit 17 through the switch 37, the common terminal 36, the relay coil 20, the output terminal 12, and the switch 15. A path is formed, and a digital signal can be output from the signal output circuit 17 to the relay coil 20 in a sink output format.

  According to the present embodiment described above, in the digital input / output circuits 32 and 35, the switch means connected externally and the common terminals 33 and 36 for the load are shared by one regardless of the input / output format. The number of terminals can be reduced as compared with the conventional configuration (see FIG. 7), which has conventionally required a separate common terminal for each source / sink input / output format, and the inverter device can be downsized. . In addition, since the common terminal is shared while the input / output format selection operation by the user is performed in the conventional manner, erroneous connection to the common terminal and erroneous operation by the user can be prevented. Further, since the switches 6 and 34 and the switches 15 and 37 are switched in conjunction with each other according to the input / output format selected by the user, the setting of the switch by the user can be simplified and erroneous setting can be prevented.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
FIG. 2 shows a configuration of display means provided in the digital input circuit 32. A light emitting element 38 is connected between the common terminal 33 and the power supply line 10 (common potential corresponding to the sink input type), and light emission is performed between the common terminal 33 and the power supply line 9 (common potential corresponding to the source input type). Element 39 is connected. The light emitting elements 38 and 39 (corresponding to display means and display) emit light when a voltage Vd is applied between the terminals, respectively, and display states (lighting / lighting) differ according to the potential of the common terminal 33. Extinguishes).

  When the switch 34 is switched to the source input format side, the light emitting element 38 emits light and the light emitting element 39 is turned off. On the other hand, when the switch 34 is switched to the sink input format side, the light emitting element 38 is turned off and the light emitting element 39 emits light. As a result, the user switches the switch 34 to the source input format side when the light emitting element 38 emits light, and switches the switch 34 to the sink input format side when the light emitting element 39 emits light. It can be easily confirmed visually. In this case, if the light emission colors of the light emitting elements 38 and 39 are different, the discrimination with respect to the setting of the current input format can be further enhanced.

  Note that only one of the light emitting elements 38 and 39 may be provided. For example, when only the light emitting element 38 is provided, it can be confirmed that the source input format is set when the light is emitted, and the sink input format is set when the light is off. When only the light emitting element 39 is provided, it can be confirmed that the sink input format is set when the light is emitted, and the source input format is set when the light is off.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.
FIG. 3 specifically shows the configuration of the digital input circuit in the inverter device, and the same parts as those in FIG. 1 are denoted by the same reference numerals. The inverter device 41 includes an inverter main circuit 42, an inverter control circuit 43, a digital input circuit 44, a digital output circuit (not shown), and the like. The inverter main circuit 42 rectifies the input AC voltage and outputs it between the DC power supply lines 45 and 46, the capacitor 48 connected between the DC power supply lines 45 and 46, the DC voltage with the command voltage and the command frequency. It is comprised from the inverter 49 which converts into an alternating voltage and outputs it. A switching element, such as an IGBT, constituting the inverter 49 is driven by a gate signal output from the inverter control circuit 43.

  The digital input circuit 44 for the contact 18 (for example, a minute current relay contact) includes an input terminal 3, a common terminal 33, a switch 50, a photocoupler 51, and resistors 52 to 54. The photocoupler 51 includes a light emitting diode connected in antiparallel between its input terminals, and a phototransistor connected between the output terminals. A resistor 53 is externally connected between the input terminals, and an output terminal is connected between the power supply lines 55 and 56 via a pull-up resistor 54. The power supply lines 55 and 56 supply the power supply voltage Vcc (5 V) of the inverter control circuit 43 and are insulated from the power supply lines 9 and 10.

  The switch 50 has a 2c contact structure composed of the switches 6 and 34 shown in FIG. 1, and the both switches 6 and 34 operate in conjunction with each other. The source input type signal input circuit and the sink input type signal input circuit are shared by a circuit mainly composed of the photocoupler 51, and are connected between the input terminal 3 and the switch 6. That is, the input terminal 3 is connected to the common contact of the switch 6 via the resistor 52 and the input terminal of the photocoupler 51, and the common terminal 33 is connected to the common contact of the switch 34. In the case of the source input format, the switch 6 is switched to the power supply line 10 side and the switch 34 is switched to the power supply line 9 side. In the sink input format, the switch 6 is switched to the power supply line 9 side and the switch 34 is switched to the power supply line 10 side. It has become.

  When the user selects the source input format, both the switches 6 and 34 are switched in conjunction so that the lower contact in the figure is turned on. When the contact 18 is turned on, a current flows from the power line 9 to the power line 10 through the switch 34, the common terminal 33, the contact 18, the input terminal 3, the resistor 52, the photocoupler 51, and the switch 6, and the photocoupler 51 is turned on. Thus, an L level digital input signal corresponding to contact ON is given to the inverter control circuit 43. When the contact 18 is turned off, the photocoupler 51 is turned off, and an H level digital input signal corresponding to the contact off is supplied to the inverter control circuit 43.

  On the other hand, when the user selects the sink input format, both the switches 6 and 34 are switched in conjunction so that the upper contact in the figure is turned on. When the contact 18 is turned on, a current flows from the power supply line 9 to the power supply line 10 via the switch 6, the photocoupler 51, the resistor 52, the input terminal 3, the contact 18, the common terminal 33, and the switch 34, and the photocoupler 51 is turned on. Thus, an L level digital input signal is applied to the inverter control circuit 43. When the contact 18 is turned off, the photocoupler 51 is turned off and an H level digital input signal is supplied to the inverter control circuit 43.

  According to this embodiment, since the common terminal is shared by one regardless of the input format, the number of terminals can be reduced, and the inverter device 41 can be downsized. In addition, the user can be prevented from erroneously connecting to the common terminal, and the setting of the switch 50 can be simplified. Furthermore, since the signal input circuit is configured by the photocoupler 51 that is turned on by bidirectional input current, the signal input circuit can be shared between the source input format and the sink input format.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.
FIG. 4 specifically shows the configuration of the digital output circuit in the inverter device, and the same parts as those in FIG. 1 or FIG. The inverter device 61 includes an inverter main circuit 42, an inverter control circuit 43, a digital output circuit 62, a digital input circuit (not shown), and the like.

  The digital output circuit 62 for the load, for example, the relay coil 20 includes an output terminal 12, a common terminal 36, a switch 63, a photo relay 64, and a resistor 65. The photorelay 64 is a bidirectional optical coupling element, and includes a light emitting diode connected between its input terminals and a photo MOSFET connected between its output terminals. Between the power supply line 55 and the output terminal of the inverter control circuit 43, the light emitting diode of the photorelay 64 and the resistor 65 are connected in series.

  The switch 63 has a 2c contact structure composed of the switches 15 and 37 shown in FIG. 1, and both the switches 15 and 37 operate in conjunction with each other. The signal output circuit of the source output format and the signal output circuit of the sink output format are shared by the circuit mainly composed of the photorelay 64 and are connected between the output terminal 12 and the switch 15. That is, the output terminal 12 is connected to the common contact of the switch 15 via the photo MOSFET of the photo relay 64, and the common terminal 36 is connected to the common contact of the switch 37. In the source output format, the switch 15 is switched to the power supply line 9 side and the switch 37 is switched to the power supply line 10 side. In the sink output format, the switch 15 is switched to the power supply line 10 side and the switch 37 is switched to the power supply line 9 side. It has become.

  When the user selects the source output format, both the switches 15 and 37 are switched in conjunction so that the upper contact in the figure is turned on. When the inverter control circuit 43 outputs an L level output signal, the photorelay 64 is turned on, and the power supply line 9 is connected to the switch 15, the photorelay 64, the output terminal 12, the relay coil 20, the common terminal 36, and the switch 37. A current flows through the power line 10 and the relay coil 20 is energized. When the inverter control circuit 43 outputs an H level output signal, the photorelay 64 is turned off and the relay coil 20 is turned off.

  On the other hand, when the user selects the sink output format, both the switches 15 and 37 are switched in conjunction so that the lower contact in the figure is turned on. When the inverter control circuit 43 outputs an L level output signal, the photorelay 64 is turned on, and from the power line 9 via the switch 37, the common terminal 36, the relay coil 20, the output terminal 12, the photorelay 64, and the switch 15. A current flows through the power line 10 and the relay coil 20 is energized. When the inverter control circuit 43 outputs an H level output signal, the photorelay 64 is turned off and the relay coil 20 is turned off.

  According to this embodiment, since the common terminal is shared by one regardless of the output format, the number of terminals can be reduced, and the inverter device 61 can be downsized. In addition, the user can be prevented from erroneously connecting to the common terminal, and the setting of the switch 63 can be simplified. Furthermore, since the signal output circuit is configured by the bi-directional output type photorelay 64, the signal output circuit can be shared between the source output format and the sink output format.

(Fifth embodiment)
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.
FIG. 5 shows a specific configuration of the display means provided in the digital output circuit 62, and the same parts as those in FIG. Between the power line 9 and the common terminal 36, a resistor 71 and a light emitting diode 72 (corresponding to a display means and a display) are connected in series. When the switches 15 and 37 are switched to the source output format side (upper contact in the figure), the light emitting diode 72 emits light, and when switched to the sink output format side (lower contact in the figure), the light emitting diode 72 is turned off. To do. That is, since the light emitting diode 72 emits light only when the source output format is switched, the user can easily check the currently set output format.

  Instead of the above configuration, the resistor 71 and the light emitting diode 72 may be connected in series between the power line 10 and the common terminal 36 with the power line 10 side as a cathode. In this case, the light emitting diode 72 emits light only when switched to the sink output format. Further, a light emitting diode may be connected between the power supply lines 9 and 10 and the common terminal 36, respectively.

(Sixth embodiment)
Hereinafter, a sixth embodiment of the present invention will be described with reference to FIG.
FIG. 6 shows a specific configuration of the display means provided in the digital output circuit 62, and the same parts as those in FIG. Connected between the common terminal 36 and the power supply line 10 is a voltage detection circuit 83 (corresponding to potential detection means) composed of a series circuit of voltage dividing resistors 81 and 82. A microcomputer 84 (corresponding to display control means) receives the detection voltage Va of the common terminal 36 output from the voltage detection circuit 83, and from a liquid crystal display, 7 segment LED, etc. based on the detection voltage Va. The display 85 (corresponding to a display) is controlled. The voltage detection circuit 83, the microcomputer 84, and the display 85 constitute display means 86.

  When the switches 15 and 37 are switched to the source output format side (upper contact in the figure), the detection voltage Va becomes 0 V (L level), and the microcomputer 84 has "source", "source output format", "source", etc. Identification information consisting of the character information is displayed on the display 85. On the other hand, when the switches 15 and 37 are switched to the sink output format side (lower contact in the figure), the divided detection voltage Va becomes 5V (H level), and the microcomputer 84 sets the “sink” and “sink output”. Identification information including character information such as “format” and “sink” is displayed on the display 85.

  According to the present embodiment, the unique character information corresponding to the output format is displayed on the display 85 according to the switching state of the switch 63 (15, 37), so that the user can easily identify the current output format. be able to.

(Other embodiments)
The present invention is not limited to the embodiments described above and shown in the drawings, and can be modified or expanded as follows, for example.
In the first embodiment, the inverter device 31 may be provided with only the digital input circuit 32 or only the digital output circuit 35.
Similarly to the second embodiment, the digital output circuit 35 is connected between the common terminal 36 and the power supply line 9 (common potential corresponding to the sink output format) and / or the common terminal 36 and the power supply line 10 (source output format). May be connected to each of the light emitting elements.

Also in the digital input circuit 44, as in the fifth embodiment, a resistor and a light emitting diode are connected in series between at least one of the power line 9 and the common terminal 33 and between the power line 10 and the common terminal 33. May be.
The digital input circuit 44 may be provided with a display means 86 as in the sixth embodiment. In this case, the digital input circuit 44 and the digital output circuit 62 can share the microcomputer 84 and the display 85.

The switch means connected to the outside is not limited to the contact point 18 and may be a logic output circuit (voltage output type, current output type), for example.
The load connected to the outside is not limited to the relay coil 20, and may be a display such as an LED or a light bulb, a logic input circuit, or the like.

1 is a schematic configuration diagram of a digital input / output circuit showing a first embodiment of the present invention. The block diagram which concerns on the display means provided in the digital input circuit which shows the 2nd Embodiment of this invention FIG. 5 is a diagram showing in detail the configuration of a digital input circuit, which is an inverter device showing a third embodiment of the present invention. The inverter apparatus which shows the 4th Embodiment of this invention, Comprising: The figure which shows the structure of a digital output circuit in detail The block diagram which concerns on the display means provided in the digital output circuit which shows the 5th Embodiment of this invention FIG. 5 equivalent view showing the sixth embodiment of the present invention 1 equivalent diagram showing the prior art

Explanation of symbols

  In the drawing, 3 is an input terminal, 6 and 15 are switches (second switching means), 7 and 8 are signal input circuits (first and second input circuits), 12 is an output terminal, and 16 and 17 are signal outputs. Circuits (first and second output circuits), 18 are contacts (switch means), 20 are relay coils (loads), 31, 41 and 61 are inverter devices, 33 and 36 are common terminals, and 34 and 37 are switches ( First switching means), 38 and 39 are light emitting elements (display means, indicator), 72 is a light emitting diode (display means, indicator), 83 is a voltage detection circuit (potential detection means), and 84 is a microcomputer (display). Control means), 85 is a display (display device), and 86 is a display means.

Claims (5)

In an inverter device capable of inputting a digital signal according to an open / closed state of a switch means connected to the outside in a source input format and a sink input format,
An input terminal to which one end of each switch means is connected;
A common terminal to which the other end of each switch means is connected in common;
First switching means for connecting the common terminal to either a first common potential corresponding to a source input format or a second common potential corresponding to a sink input format;
A first input circuit and a second input circuit, which are provided for each of the input terminals and respectively input a digital signal of a source input format and a sink input format;
And second switching means for connecting the input terminal to one of the first and second input circuits according to each input format in conjunction with the first switching means. Inverter device. In an inverter device that can output a digital signal in a source output format and a sink output format for an externally connected load,
An output terminal to which one end of each load is connected;
A common terminal to which the other end of each load is connected in common;
First switching means for connecting the common terminal to either a first common potential corresponding to a source output format or a second common potential corresponding to a sink output format;
A first output circuit and a second output circuit that are provided for each of the output terminals and output digital signals of a source output format and a sink output format, respectively;
And second switching means for connecting the output terminal to one of the first and second output circuits according to the output format in conjunction with the first switching means. Inverter device.   The inverter apparatus according to claim 1, further comprising display means for displaying different display states according to the potential of the common terminal.   4. The inverter device according to claim 3, wherein the display means is constituted by a display connected between at least one of the first and second common potentials and the common terminal.   The display means comprises a display, a potential detection means connected to the common terminal, and a display control means for displaying identification information on the display based on the detected potential. The inverter device according to claim 3.

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