JPH11261581A - Data communication control equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide data communication control equipment with which a LAN with no fluctuation in transmission time can be constructed while using 'Ethernet (R)'. SOLUTION: Time slots respectively arranged on a time base are previously allocated to data communication control equipment 30-1, to 30-n provided between respective stations 10-1 to 10-n an 'Ethernet (R)' 20, and the transmission timing of the respective stations 10-1 to 10-n is controlled so as to transmit transmission data from the respective stations 10-1 to 10-n to the 'Ethernet (R)' 20 only during the period of these previously allocated time slots by such data communication control equipment 30-1, to 30-n.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication control device, and more particularly, to a data communication control device provided corresponding to each station accommodated in a network and controlling transmission of data from the station to the network. About.

[0002]

2. Description of the Related Art In recent years, with the spread of the Internet or intranet, there has been a strong demand for constructing a LAN (local area network) in a factory using Ethernet. Ethernet is widely used for LAN in office automation (OA) environment.
The following advantages are obtained when the LAN in the factory is constructed by Ethernet.

1) A general-purpose personal computer can be easily connected. 2) Hardware / software necessary for LAN construction can be obtained at low cost. 3) Different pendant devices can be easily interconnected. 4) New technologies in LANs are often developed first for Ethernet, so that the latest technologies can be introduced without delay.

[0004]

[0005] However, the Ethernet is CSMA / CD (CarrirsenseM).
multiple Access with Colli
In order to perform access control based on the “Section Detection” method, the time from when data to be transmitted is generated to when the transmission of the data is completed (hereinafter referred to as “transmission time”) is large even if the size of the transmission data is the same. There is a problem of fluctuation.

FIG. 13 is a block diagram showing the configuration of a conventional station connected to Ethernet.

In FIG. 13, a station 10 comprises a personal computer, a PLC (programmable logic controller) and the like, and transmits and receives data to and from the Ethernet 20.

The station 10 includes a CPU (Central Processing Unit) 11 for controlling the whole of the station 10, a memory 12 for storing programs and data of the CPU 11, a transmitting unit 13 for transmitting data to the Ethernet 20, 2
Receiving unit 14 for receiving data from 0, Ethernet 20
The transmission line monitoring unit 15 monitors whether or not another station (not shown) is transmitting data.

FIG. 14 is a flowchart showing a data transmission procedure of the station shown in FIG.

In FIG. 14, when data to be transmitted from the station 10 to the Ethernet 20 shown in FIG. 13 occurs (step 101), first, another station transmits data from the output of the transmission path monitoring unit 15 to the Ethernet 20. It is checked whether it is inside (step 102). If the other station is transmitting (Y in step 102), the process returns to step 102 and waits for the transmission of the other station to end.

If it is determined in step 102 that another station is not transmitting (N in step 102), transmission of transmission data is started (step 103).

Next, it is checked whether or not the transmission of the transmission data has been completed (step 104). When it is determined that the transmission has been completed (Y in step 104), the data transmission procedure is terminated (step 107). When it is determined that the transmission of the transmission data has not been completed (N in step 104), it is checked whether another station is also transmitting (step 1).
05).

If it is determined that the other station is not transmitting (N in step 105), the process returns to step 104 to repeatedly determine whether the transmission of the transmission data has been completed.
If it is determined in step 105 that another station is also transmitting (Y in step 105), the transmission of this data is interrupted (step 106), and the process returns to step 102.

That is, in the CSMA / CD system, which is a conventional data transmission procedure of a station connected to Ethernet,
Each station connected to the LAN: 1) If another station is transmitting data, wait until the transmission of the data is completed (waiting for a free transmission path) 2) Transmit data when the transmission path is free 3) When a station detects that another station is transmitting data simultaneously during transmission (when a collision is detected), the station temporarily stops transmission, waits for a free transmission path, and then retransmits the data. Send data.

For this reason, the transmission time greatly varies depending on the amount of data on the transmission path and the frequency of occurrence of collision.

In general, a LAN in a factory is required to have real-time properties, and it must be guaranteed that data transmission is always completed within a certain time according to the amount of data. For this reason, conventionally, it was not possible to use an Ethernet having a large variation in transmission time for a LAN in a factory.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a data communication control device capable of constructing a LAN with no change in transmission time using Ethernet.

[0017]

In order to achieve the above object, the invention according to claim 1 is provided corresponding to each station accommodated in a network, and controls transmission of data from the station to the network. The data communication control device allows data transmission to the network from a station corresponding to the own device only in a time slot assigned to the own device, and in a period other than the time slot assigned to the own device, the data communication control device. Data transmission control means for prohibiting transmission of data to the network from a station corresponding to the device.

According to a second aspect of the present invention, in the first aspect of the present invention, the data transmission control means determines that the network is in use during a period other than the time slot allocated to the own device. Jam signal generating means for generating the jam signal shown and transmitting the generated jam signal to a station corresponding to the own apparatus.

According to a third aspect of the present invention, in the first aspect of the present invention, a synchronization signal transmitted over the network is received, and a time slot assigned to the own device is set based on the synchronization signal. And a time slot setting unit.

According to a fourth aspect of the present invention, there is provided a data communication control apparatus which is attached to each station and controls data transmission from each station to the network based on a time slot assigned to each station. Unit and an address setting unit, and when a specific address is set in the address setting unit, a synchronization signal is transmitted from the synchronization signal transmission unit prior to data transmission based on a time slot of a station connected to the own device. It is characterized by the following.

According to a fifth aspect of the present invention, there is provided a data communication control apparatus which is attached to each station and controls transmission of data from each station to the network based on a time slot allocated to each station. Unit, an address setting unit, and a synchronization signal monitoring unit. The synchronization signal monitoring unit detects that the synchronization signal is not received at a time when the synchronization signal should be received, and drives the synchronization signal transmission unit to detect the synchronization signal. Is transmitted.

According to a sixth aspect of the present invention, there is provided a data communication control device which accompanies each station and controls transmission of data from each station to the network based on a time slot allocated to each station. A relay unit for transmitting data received from the local network to the priority station network based on a time slot allocated to the own device.

According to a seventh aspect of the present invention, there is provided a data communication control device which is attached to each station and controls transmission of data from each station to the network based on a time slot allocated to each station. And an address setting unit, wherein a slot start time and an end time are set in the time slot setting unit based on an address set in the address setting unit and a time slot as a constant.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the outline of the present invention will be described with reference to FIG. 1. As shown in the drawing, the present invention relates to each of stations 10-1 to 10-n and Ethernet 20. Data communication control devices 30-1 to 30-
n are assigned in advance to time slots arranged on the time axis, respectively.
-N so that the transmission data from each of the stations 10-1 to 10-n is transmitted to the Ethernet 20 only within the time slot assigned in advance.
The transmission timing of n is controlled.

Hereinafter, an embodiment of a data communication control device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a system configuration of an embodiment of a data communication system constructed by employing a data communication control device according to the present invention.

In FIG. 1, stations (stations 1 to n) 10-1 to 10-1
10-n has the same configuration as the conventional station shown in FIG.

Each of the stations 10-1 to 10-n has a data communication control device (data communication control devices 1 to n) 30-1.
Connected to the Ethernet 20 via .about.30-n.

Here, the n data communication control devices 30-
1 to 30-n, one data communication control device (data communication control device 1) 30-1 is a master, and the remaining (n-
1) One data communication control device (data communication control devices 2 to 2)
n) 30-2 to 30-n operate as slaves.

Data communication control device 30 serving as a master
1 is a data communication control device 30-2 to 30-3 serving as a slave.
In addition to the function of 0-n, it has a role of repeatedly transmitting, that is, broadcasting a synchronous packet described later at a fixed period.

In FIG. 1, the data communication control device 30-1 corresponding to the station 10-1 is set as a master, but other data communication control devices, for example, the data communication control device 30-1 are used.
-2 may be the master. However, there must not be more than one master data communication control device in the system.

In the data communication system of this embodiment, a time slot is provided on the time axis, and one time slot is assigned to each of the data communication control devices 30-1 to 30-n.

FIG. 2 is a diagram showing an example of time slot assignment in the data communication system shown in FIG.

As shown in FIG. 2, the data communication control device i
(I = 1 to n) 30-i is assigned a time slot i, and each station i (i = 1 to n) 10-i is permitted to transmit data only within the period of the assigned time slot i. .

Here, the time length of each time slot is longer than the time required for transmitting the maximum size packet permitted by the Ethernet 20 so that the maximum size packet can be transmitted within one time slot. Is set to

Here, the time length of each of the time slots 1 to n may be the same or may be different for each time slot. This time slot is repeated in units of time t, and the beginning of a group of time slots is indicated by a synchronization slot.

In the synchronization slot, a synchronization packet is broadcast by the master data communication control device 30-1.

FIG. 3 is a diagram showing a comparison between an example of a frame structure of a normal packet and an example of a frame structure of a synchronization packet employed in the data communication system shown in FIG.

In FIG. 3, “PRE” is a preamble, “SFD” is a frame start delimiter, and “CRC”.
Is a CRC (Cyclic Redundancy C)
Heck) Indicates an error detection code.

In addition, the synchronous packet “FFFFFFFF
"FFFF" indicates broadcast. Here, since the data length of a normal packet does not become “64” or less, it is possible to distinguish between a synchronous packet and a normal packet by using this.

With this configuration, each time slot is repeated at a period of time t, and data from a plurality of stations does not collide. Therefore, each station always transmits a fixed amount of data every period t. It is possible to transmit, and the transmission of each station can be always completed within a certain time according to the data amount.

FIG. 4 is a block diagram showing a detailed configuration of the data communication control device serving as a slave shown in FIG.

In FIG. 4, a data communication control device (30-2 to 30-n) 30S serving as a slave shown in FIG.
Comprises a control unit 31, a reception signal monitoring unit 32, a time slot setting unit 33, a timer 34, a jam signal generation unit 35, a transmission permission switch 36, and a reception changeover switch 37.

Here, the control section 31 controls the overall operation of the data communication control device 30S serving as the slave.

The reception signal monitoring unit 32 monitors the reception signal from the Ethernet 20 and notifies the control unit 31 of the start and end of the reception of the signal from the Ethernet 20. In addition, the timer 34 is reset when a synchronization packet is received.

The time slot setting section 33 sets and stores the position of the time slot used by the own device. The time slot setting section 33 can be constituted by a dip switch or the like. This time slot setting unit 33
In, the slot start time and the slot end time of the own device's time slot are designated by relative time with the synchronization packet reception time being 0.

The timer 34 measures the elapsed time from the time when the received signal monitoring unit 32 receives the synchronization packet. Then, when the slot start time and the slot end time of the time slot set by the time slot setting unit 33 have come, the control unit 31 is notified of the start and end of the time slot of the own device. The timer 34 is reset by a signal output from the reception signal monitoring unit 32 when the reception signal monitoring unit 32 receives the synchronization packet.

The jam signal generator 35 transmits a jam signal to a station connected to the data communication control device 30S via the reception switch 37. Here, the jam signal may be any signal as long as it is different from a normal dec. For example, "0000 ..." (repeating 0) can be used.

The station connected to the data communication control device 30S determines that the transmission path, that is, the Ethernet 20, is in use while receiving the jam signal, and thus does not perform its own transmission. Also, the jam signal has a role of preventing transmission from this station outside the time slot of the own device. The start and stop of the jam signal generation by the jam signal generation unit 35 are controlled by the control unit 31.

The transmission permission switch 36 is turned ON / OFF by the control unit 31 to transmit data from the station to the Ethernet 2
Switching whether or not to transmit to 0 is performed. That is, when the transmission permission switch 36 is ON, data from the station is transmitted to the Ethernet 20, and when OFF, the data is not transmitted.

The reception changeover switch 37 is controlled by the control unit 31 and selects a signal to be transmitted to the station from three parties: 1) a jam signal, 2) a signal from the Ethernet 20, and 3) no transmission.

That is, the reception changeover switch 37 is set to the contact a
Is connected to the station, the jam signal is transmitted to the station, and when connected to the contact b, the signal from the Ethernet 20 is transmitted to the station, and is OFF, that is, is not connected to any of the contact a and the contact b. If you do not transmit anything.

FIG. 5 is a block diagram showing a detailed configuration of the master data communication control device shown in FIG.

Referring to FIG. 5, the master data communication control device (30-1) 30M shown in FIG.
1, reception signal monitoring unit 32, time slot setting unit 33,
Timer 34, jam signal generator 35, transmission permission switch 36, reception switch 37, synchronization packet transmitter 38
It comprises.

The master data communication control device 3
0M is different from the slave data communication control device 30S shown in FIG. The other configuration is the same as that of the slave data communication control device 30S shown in FIG. In FIG. 5, parts performing the same functions as those in the configuration shown in FIG. 4 are denoted by the same reference numerals as those used in FIG. 4, and detailed description thereof will be omitted.

In FIG. 5, the synchronization packet transmitting section 38
Transmits a synchronization packet to the Ethernet 20 periodically at a period of time t shown in FIG. Each of the slave data communication control devices (30-2 to 30-n) 30S
Identifies the start / end of the time slot assigned to the own device based on the reception time of the synchronization packet.

FIG. 6 is a flowchart showing the operation of the control unit of the data communication control device serving as the slave shown in FIG.

The operation of the control unit 31 of the master data communication control device 30M shown in FIG. 5 is the same as that of the flowchart shown in FIG.

In FIG. 6, the upper part of the flow chart shows the operation of the own device in a period outside the time slot, and the lower part shows the operation of the own device in a period within the time slot.

The inside and outside of the time slot can be identified by the notification of the start / end of the time slot from the timer 34.

When this operation is started outside the time slot of the own apparatus (step 301), first, the transmission permission switch 36 is turned off (step 302), and the reception changeover switch 37 is connected to the contact a, and jamming is performed. The generation of the jam signal by the signal generation unit 35 is started (Step 303).

As a result, the data from the station is not transmitted to the Ethernet 20 and the jam signal is transmitted to the station, so that the station does not transmit data.

Thereafter, when any signal, that is, transmission data or a synchronization packet of another station is received from the Ethernet 20 (Y in step 304), the reception switch 37 is connected to the contact b and the generation of the jam signal is stopped. (Step 305).

Thus, the signal from the Ethernet 20 is transmitted to the station, and the station can receive the transmission data of another station.

Here, the synchronization packet is also transmitted to the station, but since the synchronization packet has a different frame structure from ordinary data, the synchronization packet is discarded by the station.

When the reception of the signal from the Ethernet 20 is completed (Y in step 306), the receiving switch 37 is returned to the contact a again to start the jam signal generation (N in step 307, step 303).

If there is no received signal from the Ethernet 20 (N in step 304), nothing is performed until the time slot of the own device is started.

Regardless of whether or not a signal is received from the Ethernet 20, the start of the time slot is monitored during a period outside the own device's time slot, and when the own device's time slot is started (Y in step 307). , Step 3
At 11), the operation shifts to the operation in the period within the time slot of the own device.

In the own device's time slot, first, the transmission permission switch 36 is turned on (step 308), the reception changeover switch 37 is turned off, and the jam signal generation unit 35 stops generating the jam signal (step 30).
9).

As a result, the station can transmit data, and the data from the station is transmitted to the Ethernet 20 via the transmission permission switch 36.

Thereafter, the end of the own device's time slot is monitored (step 310). When the own device's time slot ends (Y in step 310), the process returns to step 302 and the operation of the period outside the own device's time slot is performed. Move to

FIG. 7 is a block diagram showing another detailed configuration of the data communication control device shown in FIG.

The basic configuration of data communication control device 30 shown in FIG. 7 is similar to data communication control device 30S shown in FIG. 4 and data communication control device 30M shown in FIG. 5, but is shown in FIG. The data communication control device 30 is different in that one data communication control device can be used as both a master and a slave.

That is, the data communication control device 30 shown in FIG. 7 is different from the data communication control device 30M shown in FIG.

In FIG. 7, data communication control device 30
Has an address unique to the device, sets the address in the address setting unit 39, and stores it.

Whether the data communication control device 30 is a master or a slave is determined as follows.

1) Data communication control device at address "1": master 2) Data communication control device at addresses "2" to "n": slave

If the address set in the address setting section 39 is "1", the synchronization packet transmitting section 38 transmits the periodic synchronization packet in the same manner as the master data communication control apparatus 30M shown in FIG. Is transmitted.

If the address set in the address setting section 39 is other than "1", the transmission of the synchronization packet is not performed similarly to the data communication control device 30S shown in FIG.

Further, the assigned time slot can be automatically set, all the time slot time lengths are set to L, and the time slot start time /
The end time is determined as follows.

1) Slot start time: L × (i−1) 2) Slot end time: L × i

The above values are set in the time slot setting section 33 shown in FIG.

With this configuration, the data communication control device 30 can be used as both a master and a slave.

FIG. 8 is a block diagram showing still another detailed configuration of the data communication control device shown in FIG.

The basic configuration of the data communication control device 300 shown in FIG. 8 is the same as that of the data communication control device 30 shown in FIG. 7, but the master data communication control device has failed and no synchronization packet is transmitted. The difference from the data communication control device 30 shown in FIG. 7 is that in any case, the data communication control device of one of the slaves becomes the master and starts transmitting the synchronization packet.

That is, in data communication control device 300 shown in FIG. 8, data communication control device 3 shown in FIG.
0, a synchronization packet monitoring unit 40 is provided.

The synchronization packet monitoring unit 40 monitors the synchronization packet on the Ethernet 20 and, based on the reception status of the synchronization packet and the address set in the address setting unit 39, the synchronization packet transmitted by the synchronization packet transmission unit 38. Control the transmission of

FIG. 9 is a flowchart showing the operation of the synchronous packet monitoring unit of the data communication control device shown in FIG.

In FIG. 9, the synchronous packet control unit 40
When the operation is started (step 401), first, the synchronous packet transmitting unit 38 is controlled to stop transmitting the synchronous packet (step 402). Then, the reception state of the synchronization packet is monitored, and if the state in which the synchronization packet is not received continues for t × (n + 1) (Y in step 403), it is determined that the master does not exist or has failed. The synchronous packet transmitting unit 38 is controlled to start transmitting a synchronous packet (step 404).

Here, t is the time length of all the slots shown in FIG. 2, and n is the address of the data communication control device.

If a synchronization packet has been received during time t × (n + 1) (N in step 403), nothing is performed.

Here, since the value of n differs for each data communication control device, a plurality of data communication control devices do not simultaneously start transmitting a synchronization packet, and the data communication control device with the smallest address first , Starts transmission of the synchronization packet. That is, the data communication control device that has started transmitting the synchronization packet becomes the master.

When a plurality of synchronization packets are received during the time t (Y in step 405), it is determined that a plurality of masters exist, and the transmission of the synchronization packets is stopped.

This is a case where a master (hereinafter, an old master) temporarily breaks down, a new master (hereinafter, a new master) starts transmitting a synchronization packet, and then the old master is restored to a normal operation. This is to prevent a plurality of masters (new master and old master) from existing at the same time.

With this configuration, even if the master fails, one of the slaves becomes the new master, so that data transmission can be performed.

FIG. 10 is a block diagram showing a system configuration of another embodiment of the data communication system constructed by employing the data communication control device according to the present invention.

Although the basic configuration of the data communication system shown in FIG. 10 is the same as that of the data communication system shown in FIG. 1, in the data communication system shown in FIG.
Multiple stations do not tolerate fluctuations in transmission time, for example, PL
A priority station such as C (programmable logic controller) and a non-priority station such as a personal computer installed in an office where the transmission time can be varied are classified into a single station. The point that the control device is shared is different from the data communication system shown in FIG.

That is, in the data communication system of this embodiment, the stations (stations 1 to n) 10-1 to 10-
n and stations (stations 1 to m) 100-1 to 100-m are priority stations 10-1 to 10-n, and non-priority stations 100-1 to 100-m
Are classified into two types.

Here, the priority stations 10-1 to 10-n are
A station in which a change in transmission time cannot be tolerated, such as a PLC.

The non-priority stations 100-1 to 100-m are stations to which fluctuations in transmission time can be tolerated, such as a personal computer installed in an office.

The configuration of each of the priority stations 10-1 to 10-n and the non-priority stations 100-1 to 100-m is the same as that shown in FIG.

The priority stations 10-1 to 10-n are connected to the priority station side Ethernet 20-1 by the non-priority stations 100-1 to 100-n.
m is connected to the non-priority station Ethernet 20-2, and the priority station Ethernet 20-1 and the non-priority station Ethernet 20
-2 is connected by the relay data communication control device 50. That is, the plurality of non-priority stations 100-1 to 100-m
Share one relay data communication control device 50.

FIG. 11 is a block diagram showing a detailed configuration of the relay data communication control device shown in FIG.

In FIG. 11, relay data communication control device 50 shown in FIG. 10 includes control unit 51, reception signal monitoring unit 52, time slot setting unit 53, timer 54, transmission relay unit 55, transmission buffer 56, reception buffer It comprises a relay unit 57, a synchronous packet transmitting unit 58, an address setting unit 59, and a synchronous packet monitoring unit 60.

Here, the reception relay unit 57 relays the data from the priority station side Ethernet 20-1 to the non-priority station side Ethernet 20-2. That is, under the control of the control unit 51, ON / OFF of the relay is controlled. The data to be relayed is also transmitted to a transmission buffer 56 described later.

The transmission buffer 56 is controlled by the control unit 51, temporarily stores the data from the non-priority station side Ethernet 20-2, and transmits the data in the transmission buffer 56 to the transmission relay unit 55 in the time slot of its own device. Then, the data is transmitted to the priority station side Ethernet 20-1 via the network.

However, the transmission buffer 56 stores the data from the non-priority station side Ethernet 20-2 and the reception relay unit 57.
If the data from the data is equal, the data is not stored. This is to prevent data from the priority-station-side Ethernet 20-1 from being accumulated in the transmission buffer 56 via the reception relay unit 57 and returning to the priority-station-side Ethernet 20-1 again.

The transmission relay unit 55 transmits the data stored in the transmission buffer 56 to the priority station side Ethernet 20-1.

Since relay data communication control device 50 does not transmit a jam signal, it does not have a jam signal generation unit.

FIG. 12 is a flowchart showing the operation of the control unit of the relay data communication control device shown in FIG.

In FIG. 12, the upper part of the flowchart shows the operation of the own apparatus in a period outside the time slot, and the lower part of the flowchart shows the operation in the period within the time slot.

The inside and outside of the time slot can be identified by the notification of the start / end of the time slot from the timer 54.

When the operation of the relay data communication control device 50 is started (step 501), the transmission of the data in the transmission buffer 56 is stopped outside the time slot of the own device (step 502). The relay of the data in the reception relay unit 57 is started (step 503).

Thereafter, nothing is performed until the time slot of the own apparatus is started (Y in step 504).

As a result, the priority station side Ethernet 20-
1 is relayed to the non-priority station side Ethernet 20-1.

The data from the non-priority station side Ethernet 20-2 is stored in the transmission buffer 56. Until the time slot of the own device is started (Y in step 504).
It is not transmitted to the priority station side Ethernet 20-1.

When the time slot of the own device is started (Y in step 504), first, the relay of the data in the reception relay unit 57 is stopped (step 505), and then the transmission of the data in the transmission buffer 56 is stopped. Start (Step 50
6).

As a result, until the time slot of the own device is completed (Y in step 507), the transmission buffer 56
The data therein is transmitted to the priority station side Ethernet 20-1 via the transmission relay unit 55.

Thereafter, when the own device's time slot ends (Y in step 507), the process returns to step 502,
The operation shifts to a period outside the time slot of the own device.

With this configuration, a plurality of stations 100-1 to 100-m that can tolerate fluctuations in the transmission time have one
The data communication control devices 50 can be shared, and the effect of reducing the LAN construction cost can be obtained.

According to the present invention, as described above, the time slots permitted to be transmitted to each station are separately allocated, the transmission data of each station is transmitted to the Ethernet only during the allocated time slots, and the time slots outside the time slots are transmitted. During this time, the transmission of the jam signal is sent to the station so that the transmission of the station is kept on standby, so that it is possible to construct an LAN that does not fluctuate in transmission time while using Ethernet. It can be enjoyed in FA.

[0122]

As described above, according to the present invention, the time slots permitted to be transmitted to each station are separately allocated, and the transmission data of each station is transmitted to the Ethernet only during the allocated time slot. During the period outside the time slot, the transmission of the jam signal is transmitted to the station so that the transmission of the station is made to stand by, so that the effect of being able to construct a LAN that does not fluctuate in transmission time while using Ethernet is obtained. Thus, the advantages of Ethernet can be enjoyed in FA.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration of an embodiment of a data communication system constructed by employing a data communication control device according to the present invention.

FIG. 2 is a diagram showing an example of time slot allocation in the data communication system shown in FIG.

FIG. 3 is a frame configuration diagram showing an example of a comparison between a frame configuration of a normal packet and a frame configuration of a synchronization packet used in the data communication system shown in FIG. 1;

FIG. 4 is a block diagram showing a detailed configuration of a data communication control device serving as a slave shown in FIG. 1;

FIG. 5 is a block diagram showing a detailed configuration of a master data communication control device shown in FIG. 1;

6 is a flowchart showing the operation of the control unit of the data communication control device serving as the slave shown in FIG.

FIG. 7 is a block diagram showing another detailed configuration of the data communication control device shown in FIG. 1;

FIG. 8 is a block diagram showing still another detailed configuration of the data communication control device shown in FIG. 1;

9 is a flowchart showing the operation of a synchronous packet monitoring unit of the data communication control device shown in FIG.

FIG. 10 is a block diagram showing a system configuration of another embodiment of a data communication system constructed by employing the data communication control device according to the present invention.

FIG. 11 is a block diagram showing a detailed configuration of the relay data communication control device shown in FIG. 10;

FIG. 12 is a flowchart showing the operation of the control unit of the relay data communication control device shown in FIG. 11;

FIG. 13 is a block diagram showing a configuration of a station connected to a conventional Ethernet.

14 is a flowchart showing a data transmission procedure of the station shown in FIG.

[Explanation of symbols]

 10-1 to 10-n station 20 Ethernet 30-1 to 30-n data communication control device 31 control unit 32 reception signal monitoring unit 33 time slot setting unit 34 timer 35 jam signal generation unit 36 transmission permission switch 37 reception changeover switch 38 Synchronous packet transmitting unit 39 Address setting unit 40 Synchronous packet monitoring unit 50 Relay data communication control device 51 Control unit 52 Received signal monitoring unit 53 Time slot setting unit 54 Timer 55 Transmission relay unit 56 Transmission buffer 57 Reception relay unit 58 Synchronous packet transmission Unit 59 address setting unit 60 synchronous packet monitoring unit

Claims (7)

[Claims] 1. A data communication control device provided corresponding to each station accommodated in a network and controlling transmission of data from the station to the network, wherein the data communication control device is provided only in a time slot allocated to the device. Data transmission control for permitting data transmission from the station corresponding to the network to the network, and prohibiting the station corresponding to the apparatus from transmitting data to the network during a period other than the time slot allocated to the apparatus. A data communication control device, comprising: 2. The data transmission control means generates a jam signal indicating that the network is in use during a period other than the time slot allocated to the own device, and transmits the jam signal to a station corresponding to the own device. 2. The data communication control device according to claim 1, further comprising: a jam signal generating unit configured to generate the jam signal. 3. A time slot setting means for receiving a synchronization signal transmitted on the network and setting a time slot allocated to the own device based on the synchronization signal. 2. The data communication control device according to 1. 4. A data communication control device attached to each station and controlling transmission of data from each station to a network based on a time slot assigned to each station, wherein a synchronization signal transmitting unit and an address setting unit are provided. Data communication control, wherein when a specific address is set in the address setting unit, a synchronization signal is transmitted from the synchronization signal transmission unit prior to data transmission based on a time slot of a station connected to the own device. apparatus. 5. A data communication control device attached to each station and controlling transmission of data from each station to a network based on a time slot allocated to each station, comprising: a synchronization signal transmitting section; an address setting section; A synchronization signal monitoring unit, wherein the synchronization signal monitoring unit detects that the synchronization signal is not received at a time when the synchronization signal should be received, and drives the synchronization signal transmission unit to transmit the synchronization signal. Data communication control device. 6. A data communication control device attached to each station and controlling the transmission of data from each station to the network based on a time slot assigned to each station, wherein the data received from the non-priority station side network is automatically transmitted. A data communication control device, comprising: a relay unit for transmitting to the priority station side network based on a time slot assigned to the device. 7. A data communication control device attached to each station and controlling transmission of data from each station to a network based on a time slot assigned to each station, comprising a time slot setting section and an address setting section. A data communication control device, wherein a slot start time and an end time are set in the time slot setting section based on an address set in the address setting section and a time slot as a constant.