JPH0563981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a runaway prevention circuit for a distributed intercom device, and more particularly to a runaway prevention circuit for a distributed intercom device having a signal channel.

[Prior Art] As shown in Fig. 4, a conventional distributed intercom device is such that a user terminal TEn (n is 1, 2, etc., and n = 12 for the sake of explanation) connects to an intercom exchange EX.
It is connected by bus. The user terminal TEn is composed of a telephone terminal and a non-telephone terminal, and the telephone terminal has an intercom exchange EX and a digital intercom face. Non-telephone terminals include facsimile machines and data terminals.

The user terminals TE ₁ to _{TE 12} and the intercom exchange EX are connected by a digital bus line 1. The digital bus line 1 consists of one signal channel and a number of communication channels suitable for the traffic of the user terminals TE ₁ to _{TE 12} , for example six channels. The signal channel is used to transmit uplink signals from the intercom exchange EX and downlink signals from the intercom exchange EX to the user terminals TE ₁ to _{TE 12} .

The user terminals TE ₁ to _{TE 12} are composed of a control circuit 2, a transmission circuit 3, a reception circuit 4, a communication circuit 5, and an overflow timer 6, as shown in FIG. The upstream signal sent from the transmission circuit 3 to the signal channel of the digital bus line 1 via the cable driver 3a is sent to the intercom exchange EX according to a predetermined protocol. Intercom exchange EX
A downlink signal sent from the terminal TEn to the user terminal TEn is input to the receiving circuit 4 via the signal channel of the digital bus line 1 and the cable receiver 4a.
The control circuit 2 transmits and receives uplink and downlink signals to control the communication circuit 5. Note that the receiving circuit 4 can receive the upstream signal sent from the transmitting circuit 3 and monitor it with the monitor 4b. Note that the signal channel is used for transmitting uplink and downlink signals (also called control signals and including data).

In the distributed intercom device with the above configuration, the response from the uplink signal from user terminal TE _{1 is monitored by the maintenance command using the downlink signal from the intercom exchange EX, and if necessary, the response from the uplink signal from the user terminal TE 1} is monitored.
TE ₁ can be initialized.

The processing of the control circuit 2 of the user terminals TE ₁ to _{TE 12} includes control of the control signal and data transmission circuit 3, control of the reception circuit 4, control of the audio signal transmission and reception circuit 5, associated internal processing, and overflow timer circuit. The maximum value of the total time of this series of processing is expressed as t, and the overflow time of the overflow timer circuit 6 is expressed as T.
When expressed as , it is set so that T>t. The overflow timer circuit 6 initializes the overflow time by applying a clear signal from the control circuit 2 within the set overflow time T, and restarts the overflow time from the time when the clear signal is applied. If a clear signal is not applied during T, a reset signal is sent to the control circuit 2. Therefore, in normal operating conditions, the maximum time t required for a series of processing by the control circuit 2 is shorter than the overflow time T of the overflow timer circuit 6, so that no reset signal is applied to the control circuit 1.

If the control circuit is unable to operate normally due to runaway or the like, the clear signal is no longer applied to the overflow timer circuit 6, and an overflow signal is sent from the overflow timer 4 to the control circuit 2 after a certain period of time. As a result, the control circuit 2 is initialized by operating an emergency circuit (not shown), and returns to a normal state.

This series of procedures related to abnormality processing is also used for initialization processing of the entire system in the distributed intercom device. Any one of the plurality of user terminals TEn connected by the digital bus line 1 is provided with a function that allows the control signal or data to be sent for a longer period than the overflow time T of the overflow timer circuit 6 of the user terminal TEn. , send this out as needed. As a result, the control circuit 2 of the other user terminal TEn continues to receive the signal input from the receiving circuit 4, and cannot apply a clear signal to the overflow timer circuit 6. Therefore, the control circuit 2 of each user terminal TEn is given an overflow signal from the overflow timer circuit 6, and the entire system is initialized.

[Problems to be Solved by the Invention] In the runaway prevention circuit of the distributed intercom device having the above configuration, an abnormality is detected in the signal channel of the digital bus line 1 by an upstream signal defined in a predetermined protocol from the transmission circuit 3 of the user terminal TEn in the runaway state. When a long signal is sent to the overflow timer 6 and a clear signal is sent from the control circuit 2 to the overflow timer 6, the overflow timer 6 is in a state in which it does not send an overflow signal to the control circuit 2. Therefore, not only is the signal channel of the digital bus line 1 blocked by an abnormal signal, resulting in a system failure, but also the user terminal TEn that is transmitting the abnormal data cannot be identified, which is a problem that must be solved.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and is provided with a transmission time check timer that operates when the signal channel is blocked due to abnormal communication of the own station, and immediately stops abnormal transmission when the transmission time check timer operates. An object of the present invention is to provide a runaway prevention circuit for a distributed intercom device that can stop the operation.

[Means for Solving the Problems] A runaway prevention circuit for a distributed intercom device according to the present invention includes an intercom exchange, an intercom terminal connected to the intercom exchange via a transmission path consisting of a signal channel and a speech channel in the form of a bus. A distributed intercom device comprising: a control circuit provided in the intercom terminal; and an overflow timer that outputs an overflow signal to the control circuit to interrupt runaway of the program when the control circuit is not cleared by a clear signal of the control circuit. , a signal channel monitoring timer that monitors the time during which the signal channel is in use and is blocked, and outputs an after-flare signal to the control circuit to interrupt runaway of the program when the blockage continues for a predetermined period of time or more. do.

[Embodiment] Hereinafter, an embodiment of a runaway prevention circuit for a distributed intercom device according to the present invention will be described with reference to the drawings.

In FIG. 1, TE ₁ is a user terminal. User terminal TE ₁ (other users include terminals TE ₂ to TE ₁₂ ) has signal channel 1 and speech channel 6.
It is connected to a digital bus line 1 consisting of channels in the bus format shown in FIG. The user terminal TE ₁ is composed of a control circuit 2, a transmission circuit 3, a reception circuit 4, a communication circuit 5, an overflow timer 6, and a signal channel monitoring timer 7.

The control circuit 2 controls the transmission circuit 3 so that the control signal sent from the transmission circuit 3 to the signal channel of the digital bus line 1 via the cable driver 3a follows a predetermined protocol. It also processes control signals input to the receiving circuit 4 via the cable receiver 4a via the signal channel of the digital bus line 1.

The communication circuit 5 communicates with other user terminals TE ₂ to TE by control signals sent and received by the transmission circuit 3 and the reception circuit 4
The control circuit 2 controls the communication channel to form a communication path with the TE ₁₂ .

As shown in FIG. 2, the overflow timer 6 is a timer of 0 to 31 bits and counts the 0.3 μs clock pulse φ ₀ input from the clock pulse generator 8 to the terminal T ₁ . During normal operation, a clear signal sent from the control circuit 2 to the terminal _T2 returns to 0 by executing a clear program (not shown) that starts every 48 mS. When the clear program is not executed, 491520 clock pulses are counted and sent from terminal _T3 to control circuit 2 every 147.5mS.
Sends an overflow signal to Upon receiving the overflow signal, the control circuit 2 activates a built-in emergent engine circuit (not shown) and performs control such as connecting and disconnecting the communication path in accordance with a predetermined order.

A signal channel monitoring timer 7 monitors the signal channel. If there is a signal on the signal channel, monitor 4
The output side of b becomes H level. When the output side of the monitor 4b becomes H level, the terminal _T2 of the signal channel monitoring timer 7 becomes H level, and the clock pulse generation circuit 8 counts the 3 mS clock pulse _φ1 input to the terminal _T1 as shown in FIG. . When the control signal being sent and received through the signal channel disappears, the terminal _T2 becomes L level and the signal channel monitoring timer 7 returns to zero. When the count value reaches 491520 while the terminal T ₂ remains at the H level, an after-flare signal is outputted from the terminal T ₃ to the control circuit 2 every 147 seconds. The control circuit 2 to which the after-flare signal is input operates in the same manner as in the case of an overflow signal, and interrupts the runaway of the program.

[Operation of the invention] When the signal channel is empty, a maintenance command is sent from the intercom exchange EX to the user terminal TE ₁ ~
When sent to TE ₁₂ , a response is sent to the intercom exchange by an uplink signal, and if necessary, the user terminals TE ₁ to _{TE 12} can be initialized with maintenance commands.

When there is a program maze in the local station and a jam of less than 147 seconds is sent from the transmitting circuit 3 to the signal channel, an overflow signal is output from the overflow timer 6 to the control circuit 2 at 147.5 mS, and the user terminal TE ₁ ~TE ₁₂ is initialized.

If the above overflow signal is not output and a jam of 147 seconds or more is sent to the signal channel, the signal channel monitoring timer 7 is activated for both the local station and other stations.
A clear signal is sent to the control circuit 2 to interrupt the runaway.

In the above embodiment, the output of the monitor 4b is made indiscriminate, but it may be configured such that priority is given to the output of the own station, and the output is not activated when another station runs out of control. The number of communication channels, the overflow timer, and the time of the signal channel monitoring timer are not limited to the above embodiments.

[Effects of the Invention] A runaway prevention circuit for a distributed intercom device according to the present invention is a distributed intercom device comprising an intercom exchange and an intercom terminal connected to the intercom exchange via a transmission path consisting of a signal channel and a speech channel in a bus format. a control circuit provided in the intercom terminal, an overflow timer that outputs an overflow signal to the control circuit to interrupt runaway of the program when the signal is not cleared by a clear signal of the control circuit, and the signal channel. and a signal channel monitoring timer that monitors the time during which the program is being used and is blocked, and when the blockage continues for a predetermined period of time, outputs an lag signal to the control circuit to interrupt program runaway. The feature is that the emergency circuit can be activated in response to blockage of the signal channel. Therefore, it is possible to prevent system failure related to signal channels.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a runaway prevention circuit for a distributed intercom device according to the present invention, FIGS. 2 and 3 are configuration diagrams of an overflow timer and a signal channel monitoring timer according to FIG. 1, and FIG. The figure is a relay system diagram of a distributed intercom device, and FIG. 5 is a block diagram of a runaway prevention circuit of a conventional distributed intercom device. 1...Digital bus line, 2...Control circuit,
6... Overflow timer, 7... Signal channel monitoring timer, EX... Intercom exchange,
TEn...User terminal.

Claims (1)

[Claims] 1. In a distributed intercom device comprising an intercom exchange and an intercom terminal connected to the intercom exchange via a transmission path consisting of a signal channel and a speech channel in a bus format, a control circuit provided in the intercom terminal;
an overflow timer that outputs an overflow signal to the control circuit to interrupt runaway of the program when not cleared by a clear signal of the control circuit;
and a signal channel monitoring timer that monitors the time during which the signal channel is in use and is blocked, and outputs an lag signal to the control circuit to interrupt runaway of the program when the blockage continues for a predetermined period of time or more. Runaway prevention circuit for distributed intercom equipment.