JPS61133798A - Lock control method for remote devices - Google Patents

Abstract

PURPOSE:To allow the titled device side to release the lock at the local site only when the center system is broken down or the communication is made impossible because of communication line is at fault by prohibiting the operation releasing the lock at the remote local site once lock is established from the center system through the communication line. CONSTITUTION:A CONT signal code is sent periodically from a center device 11 to a remote device 13 at intervals of T2 which is shorter than the pulse output time of retrigerable one-shot multivibrator 26. A signal receiving circuit 22 which receives this CONT signal issue a pulse of active low as a signal 25 at intervals of T2. The retrigerable one-shot multivibrator 26 which is supplied with the signal 25 keeps its output 27 at high level. As far as the output 27 is kept at high level, the locked state of flip-flop 28, namely the state of a control output terminal 31, does not change, even if an active low signal is generated at the terminal 29 by the local operation to release the lock.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a lock control system that can lock a local operation circuit of a remote device from a central device via a communication line.

[Prior art]

The lock control method in this type of control system conventionally used is as shown in the configuration example of FIG.
A command signal for lock setting and lock release is given from the K center device. This signal is received by a receiving circuit 2, and its outputs include a set input signal 4 and a reset input signal 5.
occurs.

The flip-flop circuit 3 receives a set input signal 4 and a reset input signal 5 and sets a locked or unlocked state. The remote device receives an output from the output terminal 6 of the flip-flop circuit 3.

The polarity is determined, and if it is in the locked state, the local operation circuit added thereto is controlled to prohibit part of the local operation.

However, with this conventional lock control method,
If a remote device is set to a locked state by the center device and the center device goes down or communication becomes impossible due to a failure in one communication line, the remote device will be locked until the center device or communication line is restored. The disadvantage was that it was not possible to perform local operations by releasing the .

[Purpose of the invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to prevent the central device from going down by prohibiting a local unlocking operation on a remote device if the lock is set from the center device via a communication line. To provide a lock control method that allows a remote device to perform a local unlocking operation even if a failure occurs in a communication line and communication becomes impossible.

[Structure of the invention]

The configuration of the present invention is applied to a remote device that receives control from a center device via a communication line, and at least one of the control operations of a circuit that locally operates the remote device is transmitted from the center device to the remote device side. A means for receiving prohibition information, and when delivery of the control operation prohibition information becomes impossible.

means for releasing the inhibited state of at least part of the circuit for locally operating the remote device by local operation'; and when delivery of the prohibition information for the control operation is possible, at least one of the circuit for locally operating the remote device; The present invention is characterized in that, when the unit is in the prohibited state, means for locking the prohibited state by local operation is provided.

[Embodiments of the invention]

Next, two embodiments according to the present invention will be described with reference to two drawings.

FIG. 2 systematically shows the control system of the remote device. In this figure, 11 is a center device, 12 is a communication line, and 13 is a remote device. FIG. 1 shows an embodiment of the invention applied to the remote device of FIG.

In this example, three types of predetermined codes (LOCK
, RELEASE and C0NT. ) is received. These signals are applied to the receiving circuit 21, which generates three types of active low 74) responses. Of these, the signal 25 is input to a retriggerable one-shot multivibrator 26, and the fall of the pulse signal serves as a trigger to output a pulse output 27 at a low level for a predetermined time Tl. What about the other two signals 24 and 23?

Two sets of set and reset signals are applied to the flip-flop circuit 28.

When a lock is released or set locally, the lock release iR signal from the terminal 29 is ANDed with the signal 27 among the active low Nockles signals applied to the terminals 29 and 30. After being taken at the gate 32, the lock setting pulse from the terminal 30 is directly input as a reset signal to the remaining set of flip-flop circuits 28.The output of the flip-flop fEJ circuit 28 is output to the output terminal 31. Output terminal 31
When the output is at a high level, it indicates a locked state. Regarding the operation of the embodiment configured in this way.

To explain in more detail, from the center device 11.

The CONT signal code is periodically transmitted to the remote device 13 at intervals T2 shorter than the pulse output time of the retriggerable one-shot multivibrator 26. The receiving circuit 22 that received this C0NT signal code receives the signal 2.
5, an active low signal is output at the interval T2 as described above. This signal 25 is applied to the retriggerable one-shot multivibrator 26 at the output 27.
maintain a high level. While the output 27 is held at a high level, even if an active low signal is generated at the terminal 29 by locally releasing the lock, the flip-flop 28 remains in the locked state, that is, the state of the control output terminal 31. does not change. Also.

LOCK and RELEASE from center device 11
, regardless of the state of output 27.

It is possible to transition the state of the flip-flop circuit 28.

Also, whether the center device 11 goes down or the communication line 12
When a failure occurs and communication becomes impossible, the signal 27 becomes low level from the maximum time Tl after the first communication failure occurs. When a local unlock operation is performed, terminal 29
When an active low signal is generated, the flip-flop circuit 28 is put into a reset state, and lock release control becomes possible.

〔Effect of the invention〕

As is clear from the above explanation, according to the method of the second invention, when a remote device is locked from the center device, it is impossible to unlock the remote device even if the remote device is operated locally during that time. Therefore, by locking operation items that could cause serious problems if the remote device is operated carelessly, problems caused by erroneous operations can be prevented. Furthermore, if communication from the center device becomes impossible, by operating the remote device locally, even if it is locked, it can be unlocked and all operations on the local device can be performed. This has great effects in improving the flexibility and reliability of control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram 2 showing the configuration of an embodiment according to the present invention.
FIG. 2 is a system diagram showing a control system of a remote device to which the embodiment of FIG. 1 is applied, and FIG. 3 is a block diagram showing a configuration example of a conventional lock control system. In the figure, 11 is a center loading unit, 13 is a remote device, and 2
2 is a receiving circuit, 26 is an IJ l-IJ multivibrator, 28 is a flip-frog circuit, and 32 is an AND dart.

Claims (1)

[Claims] 1. Applied to a remote device that receives control from a center device via a communication line, and prohibits the remote device from at least part of the control operation of a circuit that locally operates the remote device sent from the center device. means for receiving, by local operation, a prohibited state of at least a portion of a circuit for locally operating the remote device when delivery of the prohibition information for the control operation becomes impossible; When delivery of operation prohibition information is possible and at least a part of the circuit for locally operating the remote device is in a prohibited state, the remote device is characterized by further comprising means for locking the prohibited state by local operation. Lock control method.