JPH0440719A - Data transmission system - Google Patents

Abstract

PURPOSE:To automatically reset the connection between a master station and a slave station by transmitting the data while initializing a transmission controller in response to the occurrence of an untransmissible state of the master or slave station. CONSTITUTION:When a master station 2 has an untransmissible state, a watchdog timer WDT 16 counts up a prescribed time T1. Then the WDT 16 supplies a signal to a reset terminal of a transmission controller 15 in response to the count-up of the time T1 and resets the controller 15. Meanwhile a WDT 18 counts up the time T1 at a slave station 3 and resets a transmission controller 17 since no data is received from the station 2. When an untransmissible state occurs at the station 3, the WDT 18 of the station 3 related to the untransmissible state counts up a prescribed time and supplied a signal to the reset terminal of the controller 17 to reset this controller.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data transmission system in which a master station and a predetermined number of slave stations exchange information using a transmission path such as a dataway as a medium.

[Prior Art] Conventionally, systems have been known in which a master station and a plurality of slave stations are connected to a transmission path and data is transmitted between the master station and the slave stations.

For example, in the field of home automation (HA), systems for controlling air conditioners, lighting equipment, etc. are known. A master station in this system controls the operation of load equipment to which slave stations are attached and monitors the operating status. A slave station is attached to home electrical equipment such as an air conditioner or a security device such as a fire sensor.

FIG. 4 shows a schematic configuration of such a data transmission system. As shown in this figure, the transmission line (1
) is connected to a master station (2) and a plurality of slave stations (3).

The master station (2) sends data to be transmitted to the slave station (3) onto the transmission line (1) at a predetermined timing. Child station (3)
receives data supplied from the master station (2) via the transmission path (1), and at the same time receives data from the transmission path (1) at the corresponding timing.
1) Send the data to be transmitted to the master station (2) above. In this way, data transmission is performed between the master station (2) and the slave station (3).

FIG. 5 shows a more detailed example configuration of the data transmission system. The system shown in this figure is the system described in Japanese Patent Application No. 61-270306, which was previously proposed by the applicant of the present application.

A plurality of slave stations (3) shown in this figure are connected to a sub-bus (4).
and is connected to the master station (2) by a power supply path (5).

Among these, the sub-bus (4) forms a transmission path together with the main bus (6) running inside the master station (2). Power supply line (5
) is a line for supplying power to each slave station (3) and master station (2), and forms a pair with the sub-bus (4). A predetermined number of these pairs are extracted from the master station (2).

That is, a predetermined number of slave stations (3) are arranged for each pair along one of a predetermined number of pairs of sub-buses (4) and feed lines (5) drawn from the master station (2). .

The slave station (3) is composed of a sub-bus monitoring and control circuit (7) that transmits and receives data to and from the sub-bus (4), and a power receiving circuit (8) that receives drive power from the power supply line (5). There is.

For example, from the master station (2) to the slave station (3) on the sub bus (4),
When data is sent to the slave station (3), the sub-bus monitoring control circuit (7) of the slave station (3) receives it, and the slave station (3) performs necessary processing. If this system is used in an HA system, the slave station (3) to receive the data is specified by the destination address of the frame containing the data. A sub-bus supervisory control circuit (7) receives frame data specifying the slave station (3) attached to the household electrical appliance, and controls the household electrical appliance as a load device.

Conversely, when attempting to transmit data from the slave station (3), for example when attempting to notify the operating status of load equipment to the master station (2), the sub-bus supervisory control circuit (7) sends data to be transmitted to the sub-bus (4). ), and the master station (2) receives it.

In addition, the power required for the slave station (3) to perform such operations is transferred from the power supply line (5) to the slave station (by the power receiving circuit (8).
3).

On the other hand, the master station (2) has a main bus (6) connected to the sub-bus (4), a power supply circuit (9) that supplies power supply voltage to the power supply line (5), and a power supply circuit (9) that supplies the power supply voltage to the power supply line (5) and the power supply line (5). A switch circuit (10) is provided corresponding to each power supply path (5) to open and close the connection with the circuit (9), and exchanges data with the main bus (6). It consists of a main bus monitoring and control device (12) that issues opening/closing commands via a control line (11). Further, the switch circuit (10) drives and opens/closes a relay contact (13) interposed in the power supply line (5) and a relay contact (13) according to a signal from the main bus monitoring control device (12). It is composed of a relay coil (14).

That is, data transmitted from the slave station (3) via the sub-bus (4) and the main bus (6) is received by the main bus monitoring and control device (12) of the master station (2), and conversely, the data is sent to the master station ( When transmitting from 2) to slave station (3),
The main bus supervisory control device (12) sends data onto the main bus (6), and the main bus (6) and sub bus (4)
), the data is transmitted to the slave station (3).

Such data transmission is carried out by the main bus supervisory control device (1
2) by connecting the main bus (6) and necessary sub-buses (4) under the control of the switch circuit (10). For example, when transmitting data only to a group of slave stations (3) connected to a certain sub-bus (4), the main bus supervisory control device (12) of the master station (2) The remaining bus (6) and the sub-bus (4) are connected by a switch circuit (10) corresponding to the main bus (6).

In addition, if a failure occurs in the data transmission system, such as failure of transmission at the master station (2) or slave station (3),
- The data transmission of the master station (2) or slave station (3) must be stopped once in order to recover. In this conventional example, such transmission suspension is realized by opening and closing the switch circuit (10) under the control of the main bus supervisory control device (12).

That is, the switch circuit (10) is composed of a relay contact (13) and a relay coil (14) as described above. The connection between the main bus (6) and the sub-bus (4) is opened and closed via the control line (1) from the main bus monitoring and control device (12).
The signal supplied through the relay coil (14)
) is energized/de-energized by opening and closing the relay contact (]3).

For example, if a failure occurs in one of the slave stations (3) and data transmission with the slave station (3) must be stopped, the power supply line (5) connected to the slave station (3) The power supply from the power supply circuit (9) to the slave station (3) may be cut off by opening the relay contact (13) of the switch circuit (10) corresponding to the power supply circuit (9). In addition, in the master station (2), if transmission becomes impossible due to a failure in the main bus (6), for example, a switch circuit that controls the built-in switch circuit (10) and supports all power supply paths (5). Just open (10).

In this way, conventionally, either the master station (2) or the slave station (
It was possible to perform recovery work by cutting off the power supply when the failure occurred in 3).

[Problem to be solved by the invention] However, in the past, in order to restore the connection of a faulty slave station or master station, an operator has to check whether the restoration of the faulty slave station or master station has been completed. Is it necessary to check this while doing so?

In other words, it is necessary to manually restore the connection between the master station and the slave station.

The present invention was made with the aim of solving such problems, and an object of the present invention is to provide a data transmission system that can automatically restore the connection between a master station and a slave station. do.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides that the master station:
A transmission control device that designates and sends data to one of the slave stations on the transmission path at intervals of a predetermined time T1, detects the presence of data on the transmission path, starts timing for a predetermined time t1 where Tl<tl, and ends the timing. and a timer that initializes the transmission control device when the presence of data is not detected again until the slave station receives data on the transmission path and determines that this data is destined for the local station. In some cases, a transmission control device that sends data onto a transmission path within a predetermined time period of 12 from reception when TI>72 and returns the data to a master station;
a timer that detects the presence of data on the transmission path and starts counting a predetermined time t2 where T2<t2, and initializes the transmission control device of its own station when no data is detected again by the end of the counting; It is characterized by having the following.

[Operations] In the data transmission system of the present invention, the master station sends data onto the transmission path at predetermined time intervals T1. On the other hand, this is received by the slave station and the data is returned within a predetermined time of 12 seconds. The timer timers of the master station and the slave station measure times t1 and t2 of T1 < t1, T2 (t2) from the data transmission and reception of their own station, but one of the stations is sure to clock within both times t1 and 12. Since the result of data transmission is preset, the timer will not end as long as data transmission continues normally.

Now, let us consider a case where the master station becomes unable to transmit data at some point. In this case, the transmission control device of the master station is initialized when the timer of the master station finishes counting. Furthermore, if no data is sent from the master station, no data will be received by any of the slave stations and no data will be sent back.

Therefore, the time limit timer of the slave station also ends, and the transmission control device of the slave station is initialized. Then, after the transmission-disabled state of the master station is released, the above-mentioned normal operation is resumed.

Also, consider a case where the slave station becomes unable to transmit data at some point. In this case, the time-limited timer of the slave station that has become unable to transmit ends, and the transmission control device of the slave station is initialized. Thereafter, until the transmission disabled state of the slave station is released, the slave station repeatedly performs initialization operations, and the master station and other slave stations continue to operate normally. Then, the slave station returns to normal operation after the transmission-disabled state is released.

As described above, in the present invention, data transmission is performed while initializing the transmission control device automatically in response to the occurrence of a transmission-disabled state in a master station or a slave station.

[Embodiments] Preferred embodiments of the present invention will be described below with reference to the drawings. Components similar to the conventional configuration shown in FIGS. 4 and 5 are designated by the same reference numerals, and their explanation will be omitted.

FIG. 1 shows the configuration of a master station (2) that constitutes a data transmission system according to an embodiment of the present invention, and FIG. 2 shows the configuration of a slave station (3). .

The system configuration of this embodiment is similar to the data transmission system shown in FIG.
The internal configurations of the substation (3) and the slave station (3) will be explained.

In FIG. 1, the master station (2) is a transmission control device (15)
and watchdog timer (hereinafter abbreviated as WDT) (1
6).

The transmission control device (15) is connected to the transmission path (1), and transmits a signal to the slave station (3) for a predetermined period of time T1 via this transmission path (1).
Send data at intervals. It also captures data transmitted from the slave station (3) and performs predetermined processing.

The transmission line (1) is connected to the WDT (16) at its ck terminal, and its timing output is connected to the r of the transmission control device (15).
Connected to eset terminal. WDT (16) is
The transmission control device (15) starts counting a predetermined time t1 in response to the arrival of data to the ck terminal, and after counting up.
transmission control device (15) by supplying a signal to the reset terminal of
) to reset.

The time t1 counted by the WDT (16) is set to be longer than the data transmission interval T1 by the transmission control device (15).

In addition, in FIG. 2, the slave station (3) receives data transmitted from the transmission control device (15) of the master station (2) and transmits the data to the master station (2) within a predetermined time 12. The transmission control device (17) that transmits starts counting a predetermined time t2 (however, t2>T2) in response to the arrival of data from the transmission path (1), and after counting up, the transmission control device (17)
transmission control device (17) by supplying a signal to the reset terminal of
) for resetting the WDT (18).

Next, the operation of the data transmission system composed of the master station (2) and slave station (3) having such a configuration will be explained.

It is assumed that three slave stations (3) are provided for ease of explanation.

FIG. 3 shows the operation timing of this embodiment. As mentioned above, the transmission control device (15) of the master station (2)
transmits data at intervals of a predetermined time T1. Therefore, data sent from the master station (2) exists on the transmission path (1) at intervals of a predetermined time T1.

In addition, the master station (2) also sends a slave station (3) that should receive the data.
) by the destination address attached to the data, and sends the data. In this embodiment, it is assumed that three devices are designated in order.

The slave station (3) takes in the data transmitted by the master station (2) from the transmission path (1), and if the destination address attached to this data is its own address, the slave station (3) receives the data sent from the master station (2) from the transmission path (1), and if the destination address attached to this data is its own address, the slave station (3) receives the data sent from the master station (2) from the transmission path (1). After T2 has elapsed, the necessary data is sent back to the master station (2) via the transmission path (1). The data related to the return is, for example, data indicating the operation of a load device to be monitored by the own station.

The slave station (3) that sends back the data is the slave station (3) that received the data addressed to itself, so the three slave stations (3) are designated in order to send the data to the master station (2). If this is done,
The tour will take place in that order. Therefore, data transmitted from the slave station (3) on the transmission path (1) will not collide.

As a result, when no transmission failure occurs in either the master station (2) or the slave station (3) and transmission is possible normally, there is always a connection from the master station (2) to the master station (2) on the transmission path (1). Data to be sent out exists at predetermined time intervals T1, and correspondingly, data to be sent out from the slave station (3) also exists.

The WDT (18) of each slave station (3) is preset by receiving data from the master station (2), and is preset at time t2.
time. However, under normal conditions, this time t
Since the own station or another slave station (3) sends back data before the count up of 2, it is preset again. Therefore, as long as normal transmission is being performed, the count will not increase.

This also applies to the WDT (16) of the master station (2). The master station (2) transmits its own data to its WD.
Preset T(16).

Therefore, at time T1 such that tl>TI, the transmission control device (15)
If the WDT (16) repeats data transmission and the WDT (16) measures time, the WDT (16) will not count up.

The operation related to the characteristics of this embodiment is based on the parent station (2) or the slave station (3).
) This is the operation when a transmission impossible state occurs in any of the above.

First, consider a case where a transmission impossible state occurs in the master station (2). At this time, since no data is sent from the transmission control device (15), the WDT (16) is not preset. That is, unlike during normal operation, the WDT (16) counts up the predetermined time T1.

The WDT (16) supplies a signal to the reset terminal of the transmission control device (15) in response to this count-up,
Reset the transmission control device (15).

On the other hand, since no data is sent from the master station (2) to the slave station (3), the data is naturally not received.

As a result, the WDT (18) of the slave station (3) similarly counts up, causing the transmission control device (17) to be reset.

In this way, when the master station (2) falls into a state where transmission is disabled, both the master station (2) and the slave station (3) are reset.

Next, consider a case where a transmission impossible state occurs on the slave station (3) side. At this time, the VDT (18) of the slave station (3) related to the transmission disabled state counts up for a predetermined time t2, supplies a signal to the reset terminal of the transmission control device (17) of its own station, and (17) is reset.

Therefore, there are multiple slave stations (3 in this figure).
), if a transmission-disabled state occurs in a certain slave station (3), the transmission control device (17) is reset repeatedly until the transmission-disabled slave station (3) returns to a transmission-capable state. .

In this way, in the data transmission system according to this embodiment, even if either the master station (2) or the slave station (3) becomes unable to transmit, it can be automatically reset without using special remote reset means. can be remotely reset, and the master station (2) and slave station (3) can mutually monitor each other. As a result, reliability is improved and it becomes possible to configure an inexpensive data transmission system.

[Effects of the Invention] As explained above, according to the present invention, the transmission control device of the master station or slave station is initialized depending on the transmission-disabled state. It is possible to automatically restore the connection with the station, and mutual monitoring between the master station and the slave station is possible, making it possible to obtain an inexpensive and highly reliable data transmission system.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a master station constituting a data transmission system according to an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a slave station in this embodiment, and FIG. 3 is a diagram showing the configuration of a slave station in this embodiment. FIG. 4 is a diagram showing the operation timing, FIG. 4 is a diagram showing the configuration of a conventional general data transmission system, and FIG. 5 is a diagram showing the configuration of a conventional data transmission system. In the figure, (1) is the transmission path, (2) is the master station, (3) is the slave station, (15), (17) is the transmission control device, and (16) is the transmission path.
), (1g) is a watchdog timer. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent: Patent attorney Yoshi 1) Kenji (2 others) Working example 3rd F! A Configuration of the master station in the embodiment Fig. 1 Configuration of the slave station in the embodiment Fig. 2

Claims (1)

[Claims] In a data transmission system in which a master station and a predetermined number of slave stations are connected to a transmission path and data is transmitted between the master station and the slave stations, the master station transmits data on the transmission path at intervals of a prescribed time T1. A transmission control device that specifies one of the slave stations and sends data, detects the presence of data on the transmission path, starts counting a predetermined time t1 where T1<t1, and detects the presence of data again by the end of timing. The slave station has a timer that initializes the transmission control device when it is not detected, and the slave station receives data on the transmission path, and if this data is addressed to its own station, T1>T2 from reception. A transmission control device that sends data onto a transmission path and returns the data to a master station within a predetermined time T2, which is , and detects the presence of data on the transmission path and starts timing a predetermined time t2, where T2<t2. and a timer that initializes the transmission control device of its own station when the detection of the presence of data is not transmitted again by the end of time measurement.