JPH08223183A - Communication controller - Google Patents

Abstract

PURPOSE: To perform normal communication with other communication equipments by detecting that a communication bus is being driven by a own- communication equipment and disconnecting the present equipment from the communication bus when the driving period does not match with a period determined by a communication protocol. CONSTITUTION: In an initial state, the reset signals Rt of a level '1' and the output of the level '0' from a counter 29 are supplied to the input side of a flip-flop 30. Since an NPN transistor 32 is turned on by the output of the level '1' from the flip-flop 30, a relay switch 15 is turned on and the communication equipment is turned to a state connected to the communication bus 101. In this case, when the level '1' is ket inputted to a CLR bar terminal even after transfer time set by the communication protocol, the out-terminal of the counter 29 outputs the level '1'. The output of the flip-flop 30 is turned to the level '0' and the NPN transistor 32 is turned off. As a result, this communication controller 11 is released from the communication bus 101.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control device having a plurality of communication devices on a wired OR communication bus.

[0002]

2. Description of the Related Art As shown in FIG. 3, a plurality of communication devices 101-1 and 101-2 are connected to a wired OR communication bus 101.
Communication control devices to which ˜101-n are connected have been generally known.

Each communication device 10 in this communication control device
1-1 to 101-n mutually transfer data via the communication bus 101, and a conventional example of the circuit configuration thereof is shown in FIG.

In FIG. 4, each of the communication devices 101-1 to 10-1
01-n each have a communication controller 111 for controlling the communication operation of the communication device. Output data is output from the TX terminal of the communication controller 111, and the NPN transistor 113 is output via the resistor 112.
It is adapted to be supplied to the base of (bus driving transistor).

The collector of the NPN transistor 113 is
Connected to the communication bus 101 and pull-up resistor 1
It is connected to a 12V power supply via 14 and its emitter is grounded. Further, a resistor 115, a PNP transistor 116 and a resistor 1 are provided between the 12V power source and the ground.
17 are connected in series, and the base of the PNP transistor 116 is connected to the communication bus 101. Here, the resistance 117 has a value sufficiently larger than that of the resistance 115.

A resistor 11 is provided between the 5V power source and ground.
8 and the NPN transistor 119 are connected in series. The base of the NPN transistor 119 is supplied with the potential of the collector of the PNP transistor 116, and the potential of the collector of the NPN transistor 119 is applied to the RX bar terminal of the communication controller 111.

Next, the operation will be described.

When no data is transferred to the communication bus 101, the communication bus 101 is set to 1 by the resistor 114.
It is pulled up to 2V. When a “1” level is output from the TX terminal of the communication controller 111 in such a situation, the NPN transistor 113 causes the communication bus 101
Is driven to the "0" level.

Then, the PNP transistor 116 applies the "1" level to the base of the NPN transistor 119 and the "1" level to the base of the communication controller 119. As a result, the “0” level is input to the RX bar terminal of the communication controller 111.

Thus, the T of the communication controller 111 is
The inverted level of the output data output from the X terminal is transferred to the communication bus 101 and input to the RX bar terminal.

[0011]

However, the above-mentioned conventional communication control device has the following problems.

(1) When the operation of the communication controller 111 goes out of control and the TX terminal is fixed to the "1" level, the NPN transistor 113 is always turned on. As a result, the communication bus 101 continues to be driven to the “0” level, and the runaway communication device is
01 will be monopolized. Therefore, data transfer between other communication devices cannot be performed, and communication using the communication bus 101 becomes completely impossible.

(2) The same problem occurs when the NPN transistor 113 is destroyed and the communication bus 101 is fixed at "0" level.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to enable communication between other communication devices even if there is a communication device having an abnormality in the communication controller. It is to provide a communication control device that can perform normally. Another object is to provide a communication control device that can normally perform communication between other communication devices even if there is a communication device in which the bus driving transistor is destroyed.

[0015]

In order to achieve the above object, a feature of the first invention is that it has a plurality of communication devices connected to a wired OR communication bus, and drives the communication bus to provide In a communication control device that transfers data between communication devices, each communication device detects that the communication device itself is driving a communication bus, and calculates a driving period of the communication device, and driving period detection means and the driving device. When the driving period calculated by the period detection unit does not match the predetermined period defined by the communication protocol, the disconnection unit disconnects the communication device from the communication bus.

A feature of the second invention is that it has a plurality of communication devices, each of which is provided with a communication controller for controlling on / off operation of a bus driving transistor for driving a wired OR communication bus. In the communication control device that drives the communication bus under the control of (1) to transfer data between the communication devices, each communication device detects that its own communication device is driving the communication bus, and the driving period And a driving period detecting unit that calculates the driving period and the driving period calculated by the driving period detecting unit does not match a predetermined period defined by a communication protocol. And a disconnecting means for electrically disconnecting the controller from the communication bus.

A feature of the third invention is that it has a plurality of communication devices, each of which is provided with a communication controller for controlling on / off operation of a bus driving transistor for driving a wired OR communication bus. In the communication control device that drives the communication bus under the control of (1) to transfer data between the communication devices, each communication device detects that its own communication device is driving the communication bus, and the driving period When the drive period calculated by the drive period detection unit and the drive period calculated by the drive period detection unit do not match the predetermined period defined by the communication protocol, the operation of the bus drive transistor of the own communication device is performed. The operation prohibiting means for prohibiting is provided respectively.

[0018]

According to the first aspect of the invention as described above, when the driving period of the communication bus calculated by the driving period detecting means is an abnormal period which does not match the predetermined period defined by the communication protocol, , The communication device is determined to be defective and is disconnected from the communication bus. As a result, the communication device having a defect is prevented from interfering with communication between other communication devices.

According to the second aspect of the invention, when the driving period of the communication bus calculated by the driving period detecting means is an abnormal period which does not match the predetermined period defined by the communication protocol, the own communication device concerned. It is determined that the bus driving transistor or the communication controller has an abnormality as described above, and the communication device is electrically disconnected from the communication bus. As a result, it is possible to reliably disconnect the defective communication device from the communication bus, and it is possible to reliably eliminate the problem that the defective communication device hinders communication between other communication devices.

According to the third aspect of the present invention, when the driving period of the communication bus calculated by the driving period detecting means is an abnormal period which does not match the predetermined period defined by the communication protocol, the own communication device concerned. It is determined that the above-mentioned abnormality has occurred in the communication controller, and the operation of the bus driving transistor is prohibited. As a result, the communication device is actually disconnected from the communication bus, and communication between other communication devices is not disturbed by the defective communication device.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a communication device provided in a communication control device according to a first embodiment of the present invention.

The communication apparatus of this embodiment is used in the communication control apparatus shown in FIG. 3 in place of the conventional communication apparatus (see FIG. 4), and has a communication controller 11 for controlling overall communication of the apparatus. are doing. Communication controller 11
The output data output from the TX terminal of is supplied to the base of the NPN transistor 13 via the resistor 12. Further, a resistor 14 and a relay switch 15 are connected in series between the communication bus 101 and the collector of the NPN transistor 13 (bus driving transistor).

The communication bus 101 is connected to a 12V power source through a pull-up resistor 16 and also has a resistor 1
7, PNP transistor 18 and resistor 19 to ground. Further, the communication bus 101 is connected to the base of the PNP transistor 20. The emitter of the PNP transistor 20 is connected to the 12V power supply via the resistor 21, and the collector thereof is grounded via the resistor 22.

On the other hand, a resistor 23 is provided between the 5V power source and ground.
And the NPN transistor 24 are connected in series,
The resistor 25 and the NPN transistor 26 are connected in series. Then, the collector potential of the PNP transistor 18 is applied to the base of the NPN transistor 24,
The collector potential of the PNP transistor 20 is NPN.
It is adapted to be applied to the base of the transistor 26.

Further, the potential of the collector of the NPN transistor 26 is applied to the RX bar terminal of the communication controller 11, and the potential of the collector of the NPN transistor 24 is inverted by the inverter 27 and applied to one input side of the OR gate 28. Output data is supplied from the TX terminal of the communication controller 11 to the other input side of the OR gate 28, and the output of this OR gate 28 is applied to the CLR bar terminal of the counter 29.

When a "1" level is applied to the CLR bar terminal, the counter 29 counts the clock input from the CLK terminal to measure the transfer time (driving period) set by the communication protocol, and the transfer time C past
When "1" level is applied to the LR bar terminal,
It has a function of outputting "1" level from the OUT terminal.

The OUT terminal of the counter 29 is connected to one input side of the flip-flop 30, and the reset signal Rt of the communication control device is supplied to the other input side.
The output side of the flip-flop 30 is connected to the base of the NPN transistor 32 via the resistor 31. The NPN transistor 32 functions to control the switching operation of the relay switch 15 by turning on / off the current supplied from the 12V power supply to the electromagnetic coil of the relay switch 15 via the resistor 33.

Next, the operation of this embodiment will be described.

First, in the initial state, the flip-flop 3
The reset signal Rt of "1" level and the output of "0" level from the counter 29 are supplied to the input side of 0. As a result, since the NPN transistor 32 is turned on by the "1" level output from the flip-flop 30, the relay switch 15 is set to the on state, so that the communication device is connected to the communication bus 101. There is.

When output data is sent from the TX terminal of the communication controller 11 in such an initial state, the NPN transistor 13 is turned on / off according to the level of the output data, and the output data is inverted to the communication bus 101 at the inverted level. Driven by.

On the other hand, the transfer data on the communication bus 101 is
It is input to the RX bar terminal of the communication controller 11 by the PNP transistor 20 and the NPN transistor 26. That is, when the transfer data on the communication bus 101 is at the "1" level, both the PNP transistor 20 and the NPN transistor 26 are in the off state, and the "1" level is supplied to the RX bar terminal. Further, when the transfer data on the communication bus 101 is at "0" level, both the PNP transistor 20 and the NPN transistor 26 are turned on, so that the "0" level is supplied to the RX bar terminal.

Here, the TX terminal is fixed to the "1" level due to the runaway of the communication controller 11, or the NPN is used.
If the transistor 13 is destroyed, the communication bus 101
Is fixed to "0" level, the voltage generated in the resistor 14 turns on the PNP transistor, resulting in NP
The N transistor 24 also turns on. By this, "1"
The output of the level OR gate 28 is the CLR of the counter 29.
Input to the bar terminal, the counter 29 starts counting operation.

If the "1" level continues to be input to the CLR bar terminal even after the transfer time set by the communication protocol has passed, the OUT terminal of the counter 29 outputs the "1" level. Then, the output of the flip-flop 30 becomes "0" level, and the NPN transistor 32 is turned off. As a result, the relay switch 15 is turned off, so that the communication controller 11 of the communication device is released from the communication bus 101.

As described above, in the communication control device of this embodiment, the abnormal communication controller 11 or the destroyed NP is used.
Even if there is a communication device having the N-transistor 13, the communication device can be released from the communication bus 101, so that data transfer between other communication devices can be normally performed.

FIG. 2 is a circuit diagram of a communication device provided in a communication control device according to the second embodiment of the present invention. Elements common to those in FIG. 1 are designated by the same reference numerals and their description is omitted. .

The communication device of this embodiment is the same as the communication device of the first embodiment shown in FIG. 1, except that the relay switch 15 is removed and an NPN transistor 41 (operation inhibiting means) is provided instead of the relay switch 15. The base and collector are respectively connected to the collector of the NPN transistor 32 and the base of the NPN transistor 13,
The emitter of the transistor 41 is grounded.

According to this embodiment, when the NPN transistor 32 is turned off by the "0" level output from the flip-flop 30 in the above-mentioned abnormality, the NPN transistor 41 is turned on and the base potential of the NPN transistor 13 is changed. The NPN transistor 13 is constantly pulled out to prohibit the NPN transistor 13 from turning on. As a result, an abnormal communication device can be released from the communication bus 101 as in the above embodiment. Further, according to the present embodiment, since the relay switch can be used without using the relay switch, the size of the communication device can be reduced.

[0038]

As described in detail above, according to the first aspect of the invention, each communication device detects that its own communication device is driving the communication bus and calculates the driving period thereof. Since the detection means and the disconnection means for disconnecting the own communication device from the communication bus when the drive period calculated by the drive period detection means does not match the predetermined period defined by the communication protocol are provided. Even if there is a defective communication device, the other communication device can be operated normally, and the communication between the other communication devices can be normally performed.

According to the second aspect of the invention, each communication device detects the fact that the communication device is driving the communication bus and calculates the driving period by the driving period detecting means and the driving period detecting means. When the calculated driving period does not match the predetermined period defined by the communication protocol, the bus driving transistor of the communication device concerned and the disconnecting means for electrically disconnecting the communication controller from the communication bus, respectively. Since it is provided, even if there is a defective communication device, the other communication device can be operated normally, and normal communication between the other communication devices can be reliably ensured.

According to the third aspect of the invention, each communication device includes a drive period detection means for detecting that the communication device is driving the communication bus and calculating the drive period, and the drive period detection means. When the calculated driving period does not match the predetermined period defined by the communication protocol, the operation inhibiting means for inhibiting the operation of the bus driving transistor of the communication device concerned is provided, so that a defect occurs. Even if there is such a communication device, the other communication device can be operated normally, and the device can be configured only with the transistor, so that the device can be downsized.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a communication device in a communication control device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a communication device in a communication control device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a schematic configuration of a communication control device.

FIG. 4 is a circuit diagram of a conventional communication device.

[Explanation of symbols]

 11 communication controller 13 NPN transistor (transistor for bus drive) 15 relay switch 29 counter 101 communication bus 41 NPN transistor (operation prohibition means)

Claims (3)

[Claims] 1. A communication control device having a plurality of communication devices connected to a wired OR communication bus, wherein the communication devices are driven to transfer data between the communication devices. A driving period detection unit that detects that the own communication device is driving the communication bus and calculates the driving period, and the driving period calculated by the driving period detection unit matches a predetermined period defined by the communication protocol. A communication control device, comprising: a disconnecting unit that disconnects the communication device from the communication bus when the communication is not performed. 2. A plurality of communication devices, each of which is provided with a communication controller for controlling ON / OFF operation of a bus driving transistor for driving a wired OR communication bus, the communication bus being controlled by each of the communication controllers. In a communication control device for driving data to transfer data between the communication devices, each communication device detects that the communication device is driving a communication bus, and calculates a drive period of the communication device. Means, and when the driving period calculated by the driving period detecting means does not match a predetermined period defined by a communication protocol, the bus driving transistor and the communication controller of the own communication device are connected from the communication bus. A communication control device comprising: a disconnecting unit that electrically disconnects. 3. A plurality of communication devices, each of which is provided with a communication controller for controlling an on / off operation of a bus driving transistor for driving a wired OR communication bus, the communication bus being controlled by each of the communication controllers. In a communication control device for driving data to transfer data between the communication devices, each communication device detects that the communication device is driving a communication bus, and calculates a drive period of the communication device. Means and an operation prohibiting means for prohibiting the operation of the bus driving transistor of the communication device itself when the driving period calculated by the driving period detecting means does not match a predetermined period defined by a communication protocol. A communication control device comprising: