JPS6124345A - Signal output gate control system - Google Patents

Abstract

PURPOSE:To continue signal transmission between active transmitters by supervising a control signal of a gate circuit outputing a transmitted message with a timer, bringing an output section of a drive in the floating state when there is no change in the signal for a prescribed time and disconnecting forcibly the station from a bus to disconnect the own device from the transmission line if a fault of mode take place. CONSTITUTION:When a control signal for a prescribed time exists from a control signal A, a transmission driver 2 controls its output gate according to the control signal. If an internal circuit is faulty and a fault were the control signal A is consecutively at logical H takes place, timer 5 detects it, brings an output Q to logical L after a prescribed time and the output of the AND gate 4 is brought into L level even if the level of other terminal is logical H. Thus, even if the control signal A is in danger side due to runaway of th internal circuit and damage of components, that is, A=logical H remains, a failed transmitter is disconnected forcibly from a transmission line 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal output gate control method in a transmission device using a bus-type transmission line.

[Conventional technology]

As shown in Figure 4, a transmission device using a bus-type transmission line connects a transmission device (IO) to one or more common signal lines (11), and mutually transmits and receives bright signals. It is something to do.

The advantage of such a method is that (No. 11 transmission equipment is inexpensive.

(2) The system is easy to expand.

(3) If the transmission device fails, it is unlikely to affect others.

For these reasons, it is often used as a signal transmission path for industrial controllers.

The problem here is the effect of the failure mentioned in (3) above. Here, I wrote that it is unlikely to have an impact on others, but
In the case of the HAS system, if a failure occurs in a mode that causes disturbance from a certain station to the transmission path, the failed device will disturb the signals on the transmission path, making transmission between the non-faulty devices impossible. There is a problem in that it is not possible to easily and quickly discover whether a device has malfunctioned.

To explain this in detail based on the conventional transmission control circuit shown in FIG. 5, each transmission device (10) is provided with a transmission driver (2) and a reception sofa (3). , the transmission gate of the transmission driver (2) has a transmission gate control signal A unless there is an abnormality.
2, a change from L (low level) to H (high level) is generated.

[Problem that the invention seeks to solve]

In such a configuration, by setting the control signal A to "L" when an abnormality occurs in the internal circuit, it is generally possible to set the output to a floating state in the event of an abnormality. However, if a failure occurs in which the control signal A becomes "H" as a result of an abnormality in the internal circuit, the transmission gate will always be "I-1" and TXD will always be connected to the transmission line via T + and T z. (11), and other non-faulty transmission devices become unable to send and receive signals via the transmission path (1).As a result,
It becomes impossible to determine which of the transmission devices connected to the transmission path (1) is at fault. Conventionally, in such cases, methods have been taken such as using expensive detection equipment or disconnecting each transmission device from the transmission line one after another and searching for the location of the failure when transmission is restored.

An object of the present invention is to provide a system that can disconnect itself from the transmission path and continue signal transmission between healthy transmission devices when a mode failure occurs as described above. be.

Means for Solving Problem c] The present invention monitors the control signal of the gate circuit that outputs the message to be transmitted using a timer, and if there is no change in the gate control for a certain period of time, the output part of the driver is floated. By forcibly disconnecting the station from the bus, signal transmission can continue between other transmission devices.

〔Example〕

Hereinafter, the present invention will be specifically explained based on Examples. FIG. 1 shows a configuration for implementing the control method according to the present invention, and (1) in the figure is a transmission path through which this transmission device transmits and receives signals with other transmission devices, It consists of twisted pair wires or coaxial cables. (2) is a transmission driver, which operates, 1, gate controller 1
~71 force signal from AND gate (4) for roll 1-.
When is "'H" (high level), 'I', ,
T20') Output GFjJLTX D (transmission data) data A1) and outputs an output signal according to the level.

4; The output signal E from the ant gate (4) is “L” (
When the output terminal T + and 7r2 are at low level, the output terminal T + and 7r2 are in a floating state, and the data of 'l''XD is blocked, so that no active operation is performed on the transmission line (1).

(3) is a reception sofa, and reception terminals R,,R.

The received data of RXD (received data) is output according to the state of the received data.

(5) is a mono multi-timer for time monitoring, and the signal from the transmission gate control signal A is sent to the C terminal of the timer (5) at 61. ’-“H” change, the output Q
is set to "H" for a certain period of time, and when the control signal A remains fixed for a certain period of time, the output Q becomes "H" after a certain period of time.
L''.

(4) is a two-man powered AND gate, and the output E is set to "H" only when all inputs are "H". A is the transmission gate control signal, and unless there is an abnormality, the output E is set to "H" for a certain period of time unless there is an abnormality. In order to output the transmission data T.sub.XD to the output terminals T, .

Now, from the “L” of the A signal – “Tobi’s change cycle,
By increasing the timer time setting of timer (5), Q becomes "■" continuously during normal operation; therefore, during normal operation, the control signal from control signal A for a certain period of time is In some cases, the output gate of the transmission driver (2) is controlled according to the control signal.Furthermore, if an abnormality occurs in the internal circuit, generally by setting the control signal A to "L", In the event of an abnormality, it is possible to set the output to a floating state.However,
If a failure occurs in which the control signal A continues to be "H" as a result of an abnormality in the internal circuit, the timer (5) detects this and sets the output Q to "L" after a certain period of time. Force one terminal of AND gate (4) to “L”
By doing so, the output of the AND gate (4) becomes "L" even if the other terminal is "H".

By doing this, even if the internal circuit goes out of control or parts are destroyed, the control signal A will be on the dangerous side, i.e. 8-"
The faulty transmission device can be forcibly disconnected from the transmission line (11) even if it remains in the “H” state.

2 and 3 show other embodiments of the present invention,
The difference from the configuration shown in Fig. 1 is that the output signal of the timer (5) is used to drive the relay (6) via the relay driver (7), and the transmitter/receiver circuit and the transmission line (Fig. 2) or the transmitter circuit and the transmission line. Open the contact provided in (Fig. 3) and transmit the transmission line fl)
It was designed to be separated from the Note that (8) is a flywheel diode.

With this configuration, if the control signal A does not change or disappears for a certain period of time due to an internal abnormality, the contact of the relay connecting the transmission line and the transmission device will be opened after a certain period of time. Therefore, the transmission device can be mechanically disconnected more reliably.

Furthermore, although not shown, there is a method shown in FIG. 1 in which the Q signal of the timer (5) controls the E signal of the transmission driver (2) via the AND gate (4), and a method shown in FIG. 2 or 3. It is also possible to use a method using a relay in combination.

'Furthermore, in the above embodiment, the output Q of the timer (5) is used as a disconnection signal, but if a flip-flop is provided here, and once a failure occurs, the signal is memorized and the intermittent It is also conceivable to configure the system so that it can be reliably disconnected even if a failure occurs or is restored.

〔Effect of the invention〕

As described above, the present invention has the following effects.

■ By adding a simple circuit to a conventional device, the transmission driver can disconnect itself from the transmission path in the event of a failure that causes it to go into skewer mode, allowing it to continue to operate between otherwise healthy transmission devices. Signal transmission can continue without any problems.

■ It is possible to display a failure indication that there is no response from the other station on the transmission device that was transmitting signals with the monitoring device serving as the master station or the faulty transmission device, making it easy to determine which transmission device has failed. This can prevent system failure and reduce troubleshooting time.

[Brief explanation of drawings]

゛Fig. 1 is a circuit diagram showing a configuration for implementing the control circuit system according to the present invention, Figs. 2 and 3 are circuit diagrams showing other embodiments, and Fig. 4 is a circuit diagram of a bus-type transmission system. Block Diagram Showing Configuration FIG. 5 is a block diagram showing the configuration of a conventional transmission device. 0): Transmission line (2): Driver for sending and receiving (3): Huffer for receiving (4): AND gate for gate control
f51: Mono multi-timer for time monitoring (6): Relay (7); Relay driver (8): Flywheel diode (10): Transmission device A: Transmission gate control signal TXD = transmission data RXI): Reception data 1st Diagram transmission line 2: GO A Yoshikado driver 3: + To trust "1 F7 4 NIKE/JOB - TO CONTROL AND CATE 5: 4 VIEW A MOJ MARU timer FIG. 2 FIG. 3 FIG. 1 −−−−−−−−−−−−−−−−−” Figure 4■ Figure 5

Claims (1)

[Claims] 1. In a bus-type transmission line type transmission device in which an output operation is always performed on a transmission line once within a certain fixed time, a control signal of a gate circuit that outputs a message to be transmitted is controlled by a timer. A signal output gate control method that monitors and, if there is no change in gate control for a certain period of time, sets the output section of the driver to a floating state and forcibly disconnects the station from the bus.