JP3463134B2 - Communication device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates to a communication apparatus which example Bei overcurrent protection circuit to stop the supply of the power supply by detecting the overcurrent.

[0002]

2. Description of the Related Art Conventionally, for example, an on / off control signal from a control controller or the like is transmitted to an output device such as an air valve or an actuator of a machine tool or an input device such as a limit switch or various sensors. There is a control system that transmits an on / off state signal to the control controller or the like. In such a control system, a communication device as a master station is connected to the control controller in order to save wiring. Connect a communication device as multiple slave stations to each slave station, connect output devices such as actuators or input devices such as various sensors to each slave station, and send on / off control signals transmitted from the control controller to the master station and slave stations. Output to the output device via the station, or capture the on / off status signal from the input device to the slave station. There is a constitution of transmitting the control controller via the station.

[0003]

In such a control system, each communication device has a power supply circuit for supplying power to an internal circuit and an overcurrent protection circuit. For example, when an overcurrent flows in a certain control state, the protection circuit makes the output voltage unstable and the control system becomes unstable, but when the overcurrent state is released, the output voltage becomes The system will return to the original state, and the user will not be able to understand that the operation state has become unstable, and normal operation will continue as it is. Therefore, the system reliability is low. Become.

The present invention has been made in view of the above points. When an overcurrent state occurs, an unstable operation can be avoided, and even if the overcurrent state is released, Overcurrent protection circuit that can maintain the state
An object of the present invention is to provide a communication device including the.

[0005]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, the communication device of the present invention according to claim 1
Is connected to an external device and has an overcurrent protection circuit.
In the communication device, the external device is an input device or
The terminal unit to which the output device is connected,
The overcurrent protection circuit includes a detection unit that detects an overcurrent that flows in a power supply line that supplies power to the external device, a cutoff unit that cuts off the power supply line when a cutoff signal is given, and a detection unit that detects the overcurrent. Holding means for outputting the cutoff signal in response to the detection output and for holding the output state of the cutoff signal even when the detection output is exhausted.

According to a second aspect of the present invention, in the configuration of the first aspect, the cutoff means has a switching element that is inserted into the power supply line extending from a power supply circuit to a power supply output section to cut off the power supply line, The holding means is composed of a CPU, and power for driving is supplied to the CPU through a power supply line closer to the power supply circuit than the switching element.

According to a third aspect of the present invention, in the structure of the first aspect, the cutoff means has a switching element that is inserted into the power supply line from the power supply circuit to the power supply output section to cut off the power supply line, The holding means is composed of a latch circuit, and driving power is supplied to the latch circuit via a power supply line closer to the power supply circuit than the switching element.

The present invention according to claim 4 is any one of claims 1 to 3.
Communicates with other communication devices in some configuration
A communication unit, wherein the communication unit detects the detection unit.
Based on the output, when an overcurrent is detected,
It is to be transmitted to another communication device.

The present invention according to claim 5 provides the configuration according to claim 4.
The communication means includes a CPU for communication, and the CP
The holding means is composed of U.

[0011]

[0012] According to the present onset Akira according to claim 1, input devices and exit
With the force device is cut off by detecting the power line overcurrent power supply line to the external equipment to be connected, the overcurrent state retains its interrupted state be canceled, prior external device such as a non A stable operation can be avoided, and even if the overcurrent state is released, the user can surely know that the overcurrent state has occurred.

According to the second aspect of the present invention, the power supply for driving is supplied to the CPU constituting the holding means through the power supply line closer to the power supply circuit than the switching element of the cutoff means. Is detected and the power supply line is cut off by the switching element, the CPU can continue the operation and hold the output state of the cutoff signal.

According to the third aspect of the present invention, since the driving power is supplied to the latch circuit which constitutes the holding means through the power supply line closer to the power supply circuit than the switching element of the breaking means, the overcurrent is exceeded. Even if the current is detected and the power supply line is cut off by the switching element, the latch circuit can continue the operation and hold the output state of the cutoff signal.

According to the present invention of claim 4 , overcurrent is detected.
Send it to other communication device such as host device
Therefore, it is recommended to stop the system on the host device.
You can take appropriate measures.

According to the present invention of claim 5, a CP for communication is provided .
Since the holding means is composed of U, the CPU is individually
There is no need to prepare.

[0017]

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a control system equipped with a communication device according to the present invention.

This control system includes a control controller 1 and a master station 2 connected to the control controller 1.
And a plurality of communication devices 3 according to the present invention as slave stations that are bus-connected to the master station 2 via a communication cable. Each communication device 3 as a slave station includes a proximity sensor (not shown). And input devices such as limit switches are connected,
Alternatively, output devices such as relays and actuators are connected.

This control system transmits ON / OFF input data from the input device to the control controller 1 via each communication device 3 and the master station 2 as in the conventional example, and the control controller 1 receives this input. The data is fetched, arithmetic processing is performed according to a preset program, and output data of ON / OFF is output to an output device via the master station 2 and each communication device 3 to control a machine tool or the like.

As shown in the external perspective view of FIG. 2, the communication device 3 of this embodiment is connected to the communication unit 4 connected to the master station 2 via a communication cable and to the communication unit 4. In addition, it is provided with a terminal unit 5 to which an input device and an output device (not shown) are connected.

The communication unit 4 includes a connector section 6 to which a communication cable with the master station 2 is connected, a setting section 7 having a DIP switch for setting a communication speed and a node address, and an inside of the communication unit 4. A power supply terminal 8 to which a power supply for supplying the circuit and the internal circuit of the terminal unit 5 is connected, and a connector portion 10 for connecting to the terminal unit 5 via a communication cable 9.

On the other hand, the terminal unit 5 has a connector portion 12 for connecting to the communication unit 4 via a communication cable 9, a terminal block 13 for connecting an input device and an output device, and another terminal unit 5 connected in cascade. And a connector portion 14 for

In this embodiment, the power source connected to the communication unit 4 is the communication unit 4 and the communication cable 9.
It is configured to be supplied to the terminal unit 5 via the.

FIG. 3 is a diagram showing an outline of a power supply line from the communication unit 4 to the terminal unit 5.

The communication unit 4 includes a power supply circuit 15 to which power is supplied from the power supply terminal 8 and the power supply circuit 15
DC-D from which, for example, a DC voltage of 24 V is applied
The DC-DC converter 15 supplies a DC output of, for example, 5 V to an internal circuit (not shown).

The power from the power supply circuit 15 is supplied to the terminal unit 5 through the above-mentioned communication cable 9, and the terminal unit 5 is connected to the DC-DC converter 1
7, and is configured to supply power to an internal circuit (not shown) via the DC-DC converter 17.

In this embodiment, the connector portion 14 of the terminal unit 5 and the connector portion 12 of the other terminal unit 5 are connected via the communication cable 9, and the terminal unit 5 is also similarly connected. A plurality of terminal units 5 can be connected in series to the communication unit 4 to supply power from the communication unit 4 to each terminal unit 5.

The communication cable 9 is used not only for power supply but also for communication between the communication unit 4 and the terminal unit 5 of input data from the input device and output data to be output to the output device. Of course.

In this embodiment, when an overcurrent flows in the power supply line from the power supply circuit 15 of the communication unit 4 to the power supply output section to the terminal unit 5, it is detected and the power supply is cut off. In order to maintain that state, an overcurrent protection circuit is provided.

FIG. 4 is a circuit diagram showing the configuration of the overcurrent protection circuit 18 provided in the communication unit 4.

The overcurrent protection circuit 18 is supplied with power from the power circuit 15 and supplies power to the terminal unit 5 from the output terminal 19 as a power output section. Detecting means 20 for detecting an overcurrent flowing through the power supply line to the terminal 19, and shutoff for shutting off the power supply to the terminal unit 5 as an external device when the shutoff signal is given. Means 21 and holding means 22 for outputting the cutoff signal in response to the detection output of the detection means 20 and for holding the output state of the cutoff signal even when the detection output is no longer provided.

The detecting means 20 includes an overcurrent detecting resistor Rs inserted in the power supply line, a first transistor TR1 which is turned on at the time of an overcurrent based on the voltage across the overcurrent detecting resistor Rs, and the first transistor. A second transistor TR2 that gives a low-level detection output to the holding means 22 when an overcurrent occurs when TR1 is turned on is provided, and resistors R1 to R4 and capacitors C1 and C2 are provided.

The cutoff means 21 is a fifth transistor TR5 as a switching element which is inserted into the power supply line to turn on / off the power supply line, a third transistor TR3 to which a cutoff signal from the holding means 22 is given to the base, and the third transistor TR3. The fourth transistor TR4 controlled by the collector output of the transistor TR3 and the Zener diode D
z, resistors R5 to R11, and capacitors C3 and C4.

The holding means 22 is composed of a communication CPU 23, and is provided with a switching regulator (SWReg) 24 for supplying driving power to the CPU 23. The switching regulator 24 is a C
A DC power supply of 5V is also supplied to the internal circuits other than the PU 23 and corresponds to the DC-DC converter 16 in FIG.

Next, the operation of the overcurrent protection circuit 18 having the above configuration will be described with reference to the timing chart of FIG.

In FIG. 5, (A) is the power supply circuit 1.
5, the input of the switching regulator 24, (C) the activation state of the CPU 23, (D) the state of power supply to the terminal unit 5, (E) C
Input of IN terminal of PU23, (F) is OU of CPU23
The output of each T terminal is shown.

First, at startup, the output of the OUT terminal of the CPU 23 is in a high impedance state, the third transistor TR3 is off, and the fourth transistor TR4 is on until the CPU 23 starts to operate.

As shown in FIG. 5A, at t1, there is a power input from the power supply circuit 12, and when the input voltage rises above the specified voltage, the Zener diode Dz turns on and the fifth transistor TR5 turns on. When it is turned on, the supply of power to the terminal unit 5 is started at t2 as shown in FIG.

When the switching regulator 24 is activated and the power supply voltage of 5V is supplied to the CPU 23 at t3, a high level signal is input to the IN terminal of the CPU 23 at the same time as shown in FIG.

After the power supply voltage is applied to the CPU 23, the CPU 23 starts the operation at t4 after the initial processing for a certain period, as shown in FIG. 5C, recognizes that the IN terminal is at the high level, and recognizes the OUT terminal. The output is controlled to the low level as shown in FIG. 5 (F), and the power supply to the terminal unit 5 is continued. In this normal operation, the first and second transistors TR1 and TR2 are
Both are off.

Next, the operation when overcurrent is detected will be described.

At t5, when an overcurrent flows in the overcurrent detection resistor Rs, a voltage drop occurs between V _{BE of} the first transistor TR1 and the first transistor TR1 is turned on, whereby the second transistor TR2 is turned on. As the base becomes high level and the second transistor TR2 is turned on, FIG.
As shown in (E), the IN terminal of the CPU 23 changes from the high level to the low level, and the low level detection output is given to the CPU 23.

When the CPU 23 recognizes that a low level signal has been input to the IN terminal, it becomes an interrupt process and controls the output of the OUT terminal to a high level and outputs a cutoff signal at t6. Transistor T
R3 is turned on and the fourth transistor TR4 is turned off, whereby the fifth transistor TR5 is turned off and the power supply line is cut off to cut off the supply of power to the terminal unit 5.

In the CPU 23, the overcurrent state is released, the first and second transistors TR1 and TR2 are turned off, and the CPU
Even if the input of the IN terminal of 23 becomes high level and the detection output is not provided, as shown in FIG.
The output state of the cutoff signal is held and the cutoff state is held.

In this embodiment, the CPU 23 is a CPU for communication as described above, and transmits the input data from the input device connected to the terminal unit 5 to the master station 2, while the master station 2 In the same manner as the conventional communication of receiving the output data of the above and outputting it to the output device connected to the terminal unit 5 through the terminal unit 5, in the present embodiment, as described above, When the overcurrent is detected and the power supply line is cut off, the fact that the overcurrent is detected is transmitted to the master station 2.

Upon reception of this, the master station 2 performs an appropriate operation such as stopping the entire system or notifying the user according to a preset program.

As described above, when the overcurrent is detected, the power supply line is cut off, the power supply to the terminal unit 5 is cut off, and the state is maintained.
There is no unstable operating state as in the conventional example, and the user can also reliably know that an overcurrent state has occurred, and it is possible to debug the system abnormality that causes an overcurrent state. The reliability can be improved.

Further, in this embodiment, the blocking means 21
Since the Zener diode Dz is provided in the device, if the output voltage becomes sluggish for some reason, the output is cut off to avoid unstable operation, thereby further improving the system reliability. improves.

In the above-described embodiment, C for communication is used.
Although PU is also used as the holding means of the overcurrent protection circuit, it may be a separate CPU as another embodiment of the present invention.

As another embodiment of the present invention, the holding means of the overcurrent protection circuit may be constituted by a latch circuit instead of the CPU.

In the above-described embodiment, the overcurrent protection circuit is provided in the communication device, but the overcurrent protection circuit of the present invention may be provided not only in the communication device but also in various devices. Alternatively, it may be provided in a device to which an external device is connected to supply power to the external device.

[0054]

As described above, according to the present invention, the input device
Power supply that supplies power to external devices to which the output device and output device are connected
It detects the overcurrent of the line and shuts off the power supply line, and maintains the shutoff state even if the overcurrent state is released, so it is possible to avoid the unstable operation of external equipment as in the past and to prevent the overcurrent state. Even if is canceled, the user can surely know that the overcurrent state has occurred.

Further, according to the present invention, when an overcurrent is detected, it is transmitted to another communication device such as a host device, so that it is possible to take appropriate measures such as stopping the system, and at the same time, the user can Makes it possible to debug system abnormalities that result in an overcurrent condition.
The reliability of the system can be increased.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a control system including a communication device according to an embodiment of the present invention.

FIG. 2 is an external perspective view of the communication device in FIG.

FIG. 3 is a diagram showing a power supply line between a communication unit and a terminal unit.

FIG. 4 is a circuit diagram showing a configuration of an overcurrent protection circuit.

FIG. 5 is a timing chart used for explaining the operation.

[Explanation of symbols]

2 parent stations 3 communication devices 4 Communication unit 5 terminal units 15 power supply circuit 18 Overcurrent protection circuit 20 Detection means 21 Blocking means 22 holding means 23 CPU

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-311636 (JP, A) JP-A-6-225439 (JP, A) JP-A-7-184320 (JP, A) JP-A-7- 180385 (JP, A) JP-A 1-148017 (JP, A) JP-A 4-291569 (JP, A) Actual development 6-11011 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02H 3/08-3/10 H02H 7/20 H02H 13/00

Claims (5)

(57) [Claims] 1. An external device is connected and an overcurrent is generated.
A communication device having a protection circuit, wherein the external device is a device to which an input device or an output device is connected.
The overcurrent protection circuit is a terminal unit for supplying power to the external device, and detects the overcurrent flowing in the power supply line and the power supply line when a cutoff signal is applied. It is characterized by comprising: a shutoff means for shutting off, and a holding means for outputting the shutoff signal in response to the detection output of the detection means, and for holding the output state of the shutoff signal even when the detection output is exhausted. Communication device. 2. The cutoff means includes a switching element that is inserted into the power supply line extending from a power supply circuit to a power supply output section to cut off the power supply line, and the holding means includes a CPU, and the switching element. 2. The communication according to claim 1, wherein driving power is supplied to the CPU via a power line closer to the power circuit than the power line.
apparatus. 3. The cutoff means includes a switching element that is inserted into the power supply line from a power supply circuit to a power supply output section to cut off the power supply line, and the holding means is configured by a latch circuit, and the switching circuit is provided. 2. The communication device according to claim 1, wherein driving power is supplied to the latch circuit via a power supply line closer to the power supply circuit than an element . 4. A communication hand for communicating with another communication device.
A step, the communication means is a detection output of the detection means.
When it detects an overcurrent based on
The communication according to any one of claims 1 to 3, which is transmitted to a communication device.
Communication device. 5. The communication means comprises a CPU for communication.
The holding means is constituted by the CPU.
4. The communication device according to 4 .