JPH04330836A - Communication controller and communication control method - Google Patents

Abstract

PURPOSE:To enable a communication between a primary station and the other secondary station even when a fault occurs at one part of the secondary station, or a power source is not supplied. CONSTITUTION:A transmitting and receiving part 12 having a receiving terminal Rx and a transmitting terminal Tx, CPU 13 which outputs a clear command to a WDT 16 at every constant time interval, and WDT 16 which starts a clock when the power source is supplied, drives a relay 17 until a clock value is beyond a prescribed value, and stops the driving of the relay 17 when the clock value is beyond the prescribed value, are connected through an inside bus 15 with one another. As for the relay 17, the first pole make contact a1 is connected with the receiving terminal Rx of the transmitting and receiving part 12, the first pole brake contact b1 is connected with the second pole brake contact b2, the first pole common c1 is connected with an upstream side loop circuit 18, the second pole make contact a2 is connected with the transmitting terminal Tx of the transmitting and receiving part 12, and the second pole common c2 is connected with a downstream side loop circuit 18.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control device and a communication control method for a secondary station in a loop type transmission network.

0002

2. Description of the Related Art As shown in FIG. 5, a conventional communication control device includes a communication control device 31 for a primary station, communication control devices 32, 33, 34, 35, 36, etc. for a plurality of secondary stations. Yes, communication control devices 31, 32, 33, 34 of these stations
, 35, and 36 are connected in a loop by a loop line 18 to form a loop transmission network. The transmission data used is transmitted, for example, in a form called a frame adopted in the HDLC procedure, and is usually transmitted from the communication control device 31 of the primary station to the communication control devices 31, 32, 3 of each secondary station.
Loop line 1 while sequentially relaying 3, 34, 35, 36
8 in the clockwise direction shown in the diagram.

[0003] Each of the above communication control devices 31, 32, 33, 3
4, 35, and 36 each include a receiving end Rx connected to the upstream loop line 18 and a transmitting end Tx connected to the downstream loop line 18, as shown in FIG. A transmitting/receiving unit 42 that interfaces between each loop line 18 on the downstream side and the inside, and a central processing unit (hereinafter referred to as "CPU") 43 as a control means.
and memory 44 are connected via an internal bus 45. Recently, each of the above communication control devices 3
Each of the circuits 1, 32, 33, 34, 35, and 36 is housed in one or several chips of LSI.

[0004] As shown in FIG. 7, the transmitting/receiving section 42
a receiver 51 whose input end is connected to the receiving end Rx;
The input terminal is connected to the output terminal of the receiver 51, and the input terminal is connected to the CPU 43 (see FIG. 6) via the internal bus 45 (see FIG. 6).
a receiving circuit 54 to which an output end (not shown) is connected;
A driver 52 whose input terminal is connected to the output terminal of the receiver 51 via a selector 53 and whose output terminal is connected to the transmitting terminal Tx, and the CPU 43 (see FIG. 6) via an internal bus 45 (see FIG. 6) ) is connected to an input terminal (not shown), and an output terminal is connected to the driver 52 via the selector 53.
and a transmitting circuit 55 connected to the input terminal of the transmitter.

The selector 53 normally disconnects the transmitting circuit 55 and connects the input end of the driver 52 to the output end of the receiver 51, as shown in FIG. , 32, 33, 34, 35, and 36 respectively take in transmission data from each station on the upstream side, and at the same time, relay the transmission data to each station on the downstream side. Therefore, the transmission data sent from the communication control device 31 of the primary station is transmitted to the communication control device 31 of all the secondary stations.
, 32, 33, 34, 35, and 36, and returns to the communication control device 31 of the primary station after making a complete loop. When the communication control devices 31, 32, 33, 34, 35, and 36 of each secondary station transmit, the selector 53 is switched to the transmission circuit 55 side to cut off the transmission data from the upstream side, and the station itself Transmits the transmission data to the downstream side and transmits the transmission data to the communication control device 3 of the primary station.
Tell 1.

[0006]

[Problem to be solved by the invention] In the above conventional technology,
In some secondary stations, if a failure occurs in which the transmitter/receiver selector remains switched to the transmitter circuit side due to a hardware failure or failure in the communication control device, or a software failure. Since the loop line remains cut off, not only communication between the primary station and the failed secondary station becomes impossible, but also communication between all stations in the network becomes impossible. Also,
Even if power is not supplied to any of the communication control devices of the secondary station, the receiver and driver thereof will not operate, resulting in a similar problem in that communication between all stations in the network will be disabled.

The present invention has been made in view of the problems of the conventional technology described above, and is applicable when a failure occurs in some secondary stations or when power is not supplied to a loop transmission network. It is an object of the present invention to provide a communication control device and a communication control method that enable communication between a primary station and other secondary stations even in the case of a secondary station.

[0008]

[Means for Solving the Problems] In order to achieve the above object, a communication control device of the present invention includes a receiving end that receives transmission data from the upstream side in the transmission direction, and a reception end that transmits the transmission data to the downstream side in the transmission direction. In a communication control device used for a secondary station of a loop-type transmission network in which a plurality of secondary stations each having a transmitting/receiving unit with a transmitting end are connected in a loop to a primary station by a loop line, the transmitting/receiving unit The device is characterized by having a bypass means for bypassing the transmitting/receiving section in the event of a failure of the transmitting/receiving section.

The communication control device of the present invention has a first state in which the bypass means is connected to the upstream loop line and disconnected from the transmitting end of the transmitting/receiving section, and a first state in which the bypass means is connected to the transmitting end of the transmitting/receiving section. , and has a switching end that can be switched between a second state in which the loop line on the upstream side is cut off, and that is always in the first state when power is not supplied to the communication control device, a timekeeping means for setting the switching end to the second state when the switching end is connected to a downstream loop line, power is supplied to the communication control device, and a timed value does not exceed a predetermined value; When the communication control device is operating normally, the communication control device may be configured to include a control means for clearing the time value of the time measurement means at regular intervals so that the time value does not exceed a predetermined value.

In this case, the switching end can be a common of a relay whose make contact is connected to the transmitting end of the transceiver section.

Further, the communication control device of the present invention has a first state in which the bypass means is connected to the receiving end of the transmitting/receiving section and is cut off from the transmitting end of the transmitting/receiving section; and a second state in which it is connected to the receiving end of the transmitter/receiver and is disconnected from the receiving end of the transmitting/receiving section, and the switching end is always in the first state when power is not supplied to the communication control device. and when the switching end is connected to a downstream loop line, power is supplied to the communication control device, and the clock value does not exceed a predetermined value, the switching end is placed in the second state. The communication control device is configured to have a timekeeping means and a control means for clearing the timed value of the timekeeping means at regular intervals so that the timed value does not exceed a predetermined value when the communication control device is operating normally. You can also do that.

[0012] In this case, the switching terminal can be a common of a relay whose break contact is connected to the receiving end of the transmitting/receiving section and whose make contact is connected to the transmitting end of the transmitting/receiving section.

Furthermore, the communication control method of the present invention each includes a transmitting/receiving section having a receiving end that receives transmission data from the upstream side in the transmission direction, and a transmitting end that transmits the transmission data to the downstream side in the transmission direction. In a communication control method for a secondary station in a loop transmission network in which a plurality of secondary stations are connected in a loop by a primary station and a loop line, when power is not supplied to the secondary station, When the transmitting end is cut off from the loop line and the loop lines on the upstream and downstream sides are connected to each other, the transmitting end is set to the first state, and when power is supplied to the secondary station, timekeeping starts and the loop lines on the upstream and downstream sides are connected to each other. When the secondary station is operating normally, the time value is The time value is cleared at regular intervals so that the time value does not exceed a predetermined value, and when the time value exceeds a predetermined value, the state returns to the first state, disconnects only the secondary station, and disconnects the upstream station. This system is characterized in that a loop line and a downstream loop line are connected to each other to restore a loop type transmission network.

[0014]

[Operation] When power is not supplied to the communication control device, the receiving end of the transmitting/receiving section and the upstream loop line are connected to each other, and the transmitting end of the transmitting/receiving section is cut off from the loop line. It has become. Therefore, if the primary station and other secondary stations are already up, communication between these stations is possible.

[0015] When power is supplied to the communication control device, the timer starts measuring time, and the loop lines on the upstream and downstream sides are cut off, and the loop line on the downstream side and the transmitting end of the transmitting/receiving section are cut off. Switch to a second state in which they are connected to each other. When the communication control device is operating normally, the second state continues because the control means clears the time value of the time measurement means at regular intervals so that the time value does not exceed a predetermined value.

When some kind of failure occurs and the time value of the timer exceeds a predetermined value, the switching end returns to the first state, disconnects only the communication control device of the secondary station, and disconnects the upstream loop line. and downstream loop lines to each other to restore the loop transmission network. Therefore, communication between the primary station and other secondary stations is still possible.

[0017]

[Embodiment] An embodiment of the present invention will be explained based on the drawings.

FIG. 1 shows the configuration of a first embodiment of the communication control device of the present invention, and the communication control device 11 of this embodiment is shown in FIG.
It is applicable to each secondary station of the loop transmission network shown in FIG. In this embodiment, the receiving end Rx connected to the upstream loop line 18 and the first
A transmitting/receiving unit 12 includes a transmitting end Tx connected to the make contact a2 of the pole and serves as an interface between each loop line 18 on the upstream side and the downstream side and the inside, and a central processing unit (hereinafter referred to as a central processing unit) as a control means. (referred to as "CPU") 13 and memory 14 are connected via an internal bus 15, and a watchdog timer 16 as a clock means and a relay 17 having a common c2 as a switching terminal are added. It has become. However, the loop line 18 on the downstream side and the transmitting end Tx of the transmitting/receiving unit 12 are not directly connected, but are configured to be connected only via the relay 17, and the CPU 13 is provided with a clear command to be described later. A program that outputs is attached.

[0019] Watchdog timer (hereinafter referred to as "WDT")
That's what it means. ) 16 is equipped with a time counter (not shown) and is connected to the CPU 13 via the internal bus 15. When power is supplied, the time counter starts measuring time from the initial value, and a clear command is output from the CPU 13. The time counter is cleared and time measurement is restarted from the initial value. During time measurement, the WDT 16 sets the time value of the time counter to a predetermined value (hereinafter referred to as "timeout value").
That's what it means. ) is configured to output a drive signal for driving the relay 17 until the timeout value exceeds the timeout value, and to stop outputting the drive signal when the timeout value exceeds the timeout value.

[0020] When a failure occurs in the transmitter/receiver 12, the transmitter/receiver 12
The relay 17, which serves as a bypass means for bypassing the The break contacts b2 are connected to each other, and the first pole common c1 is connected to the upstream loop line 18.
It is connected to the. Further, the make contact a2 of the second pole is connected to the transmitting end Tx of the transmitting/receiving section 12, and the common c2 of the second pole as a switching end is connected to the loop line 18 on the downstream side. A relay coil (not shown) is connected to the output end of the drive signal of the WDT 16.

Next, the operation of this embodiment will be explained.

When power is not supplied to the communication control device 11, the first pole common c1 of the relay 17 is connected to the break contact b1 side, and the second pole common c2 is connected to the break contact b2 side. The upstream and downstream loop lines 18 are short-circuited to each other, and the transmitting end Tx of the transmitting/receiving section 12 is disconnected from each loop line 18, which is the first state. Therefore, if the primary station and other secondary stations are already up, communication between these stations is possible.

[0023] When power is supplied to the communication control device 11,
The time counter of the WDT 16 starts counting time, and a drive signal for driving the relay 17 is output from the WDT 16 . The relay 17 switches the first pole common c1 to the make contact a1 side and the second pole common c2 to the make contact a2 side to enter the second state, and each loop line on the upstream side and downstream side 18 is cut off, and the loop line 18 on the downstream side and the transmitting end Tx of the transmitting/receiving section 12 are connected to become operational.

[0024] During this operational state, the CP that is operating normally
U13 outputs a clear command according to the added program at fixed time intervals slightly shorter than the time when the time value of the time counter of the WDT 16 changes from the initial value to the timeout value, thereby clearing the time counter of the WDT 16. W.D.
The time counter T16 repeats counting up and clearing without the time value exceeding the timeout value, so it continues to output a drive signal for driving the relay 17. Therefore, the communication control device 11 operates substantially in the same way as the conventional communication control devices 32 to 36 shown in FIGS. 5 and 6, respectively (i.e., is compatible).
.

[0025] Due to some failure, the clear command that should be output at regular time intervals is not output, so WDT16
is not cleared and the clock value of the WDT 16 exceeds the timeout value, the WDT 16 stops outputting the drive signal for driving the relay 17, and each contact of the relay 17
Returning to the state described above when power is not supplied, only the communication control device 11 of the secondary station is disconnected, and each loop line 18 on the upstream and downstream sides is short-circuited to restore the loop transmission network. Therefore, communication between the primary station and other secondary stations is still possible.

FIG. 2 shows how the present invention is applied to an injection molding machine, and each part of the injection molding machine 20 includes a control panel unit 21, a mold plate ejector control unit 22, a local box unit 23, and an injection control unit 24. A cable 25 that is provided and connects each control unit is routed through a duct (not shown).

In this way, in an injection molding machine in which each control unit is connected by a loop line, even if a failure occurs in the communication control device of one control unit, only the failed control unit can be disconnected and operated. Therefore, the safety and reliability of the injection molding machine can be improved. In addition, a plurality of such injection molding machines 20 may be installed, each serving as a secondary station (a secondary station other than the injection molding machine may coexist), and these may be connected via a loop line to provide one By centralizing control using local control devices, it is possible to disconnect only the injection molding machine where the problem has occurred and allow the other injection molding machines to operate normally.
This reduces the chances of the entire system stopping. Injection molding machines generally require high efficiency, so if they can continue operating even if other machines fail, it will be possible to promote unmanned systems and reduce the cost of molded products.

FIG. 3 shows the configuration of a second embodiment of the communication control device of the present invention.

In the communication control device 11a of this embodiment, the relay 17a has a two-pole structure as in the first embodiment, and the break contact b1 of the first pole is connected to the upstream loop line. 18 and the receiving end Rx of the transmitting/receiving section 12, the first pole common c1 is connected to the second pole break contact b
2, the second pole common c2 serving as a switching end is connected to the loop line 18 on the downstream side, and the second pole make contact a2 is connected to the transmitting end Tx of the transmitting/receiving section 12. The rest of the configuration is the same as that of the first embodiment shown in FIG. 1, so a description thereof will be omitted.

In each of the embodiments described above, the structure uses two poles of the relay 17, but the structure is not limited to this.
For example, a configuration using only one pole of the relay 17 may be used. In this case, the relay 17 using only one pole, like the communication control device 11b which is the third embodiment shown in FIG.
The break contact b2 of b is connected to the loop line 18 on the upstream side and the receiving end Rx of the transmitting/receiving section 12, the common c2 as a switching end is connected to the loop line 18 on the downstream side, and the make contact a2 is connected to the transmitting end Rx of the transmitting/receiving section 12. Just connect it to the end Tx.

Further, in each of the embodiments, a relay common is used as a switching terminal, but the switching terminal is not limited to this, and for example, a photoMOS relay (analog switch) or the like may be used.

[0032] In addition, the CPU 13 not only outputs a clear command at regular time intervals, but also detects when a frame of transmitted data from the primary station is not normally received at preset time intervals with the primary station. It is more effective if the clear command is not output when the communication control hardware and software are checked.

[0033]

[Effects of the Invention] Since the present invention is constructed as described above, it produces the following effects.

In a loop type transmission network, even if a failure occurs in some secondary stations or power is not supplied, only the communication control device 11 of the secondary station is disconnected and the upstream and downstream sides are disconnected. The loop transmission network can be restored by short-circuiting each loop line 18,
Communication between other secondary stations and primary stations becomes possible. Therefore, the reliability of the network as a whole increases.

In particular, when the secondary station is an injection molding machine,
The cost of molded products can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the configuration of a first embodiment of a communication control device of the present invention.

FIG. 2 is a perspective view showing an example in which the present invention is applied to an injection molding machine.

FIG. 3 is a schematic configuration diagram showing the configuration of a second embodiment of the communication control device of the present invention.

FIG. 4 is a schematic configuration diagram showing the configuration of a third embodiment of the communication control device of the present invention.

FIG. 5 is a block diagram showing a configuration example of a loop-type transmission network.

FIG. 6 is a schematic configuration diagram showing a conventional example of a communication control device.

7 is a schematic configuration diagram showing the configuration of a transmitting/receiving section in the communication control device shown in FIG. 6. FIG.

[Explanation of symbols]

11, 11a, 11b communication control device 12
Transmission/reception unit 13 Central processing unit 14 Memory 15 Internal bus 16 Watchdog timer 17, 17a, 17b Relay 18 Loop line 20 Injection molding machine 21 Control panel unit 22 Mold plate ejector control unit 23
Local box unit 24 Injection control unit 25 Cable

Claims (6)

[Claims] Claim 1: A transmitting/receiving unit (12
) in a communication control device used as a secondary station of a loop-type transmission network in which a plurality of secondary stations each having a primary station and a loop line (18) are connected in a loop by a loop line (18). A communication control device comprising bypass means (17) that bypasses the transmitter/receiver (12) in the event of a failure. 2. A first state in which the bypass means (17) is connected to the upstream loop line (18) and is cut off from the transmitting end (Tx) of the transmitting/receiving section (12); (12) is connected to the transmitting end (Tx) and is cut off from the upstream loop line (18), and when power is not supplied to the communication control device, The loop line (18) has a switching end (c2) that is always in the first state, and the switching end (c2) is on the downstream side.
is connected to the communication control device, and when power is supplied to the communication control device and the clock value does not exceed a predetermined value, the switching end (c2
) to the second state, and when the communication control device is operating normally, the clocking means (16)
2. The communication control device according to claim 1, further comprising control means (13, 14) for clearing the timed value at regular intervals so that the timed value does not exceed a predetermined value. [Claim 3] The switching end (c2) is a make contact (a2
) is a common of a relay (17) connected to a transmitting end (Tx) of the transmitting/receiving section (12). 4. The bypass means (17) includes a transmitting/receiving section (
12) is connected to the receiving end (Rx) of the transmitter/receiver (12) and disconnected from the transmitter end (Tx) of the transmitter/receiver (12); and is,
and a second state in which the receiving end (Rx) of the transmitting/receiving unit (12) is cut off, and the switching is always in the first state when power is not supplied to the communication control device. when the switching end (c2) is connected to the downstream loop line (18), power is supplied to the communication control device, and the timed value does not exceed a predetermined value; When the timer (16) for setting the switching end (c2) in the second state and the communication control device are operating normally, the timer value of the timer (16) does not exceed a predetermined value. A control means (
13, 14). The communication control device according to claim 1. 5. The switching end (c2) is a break contact (b
2) is connected to the receiving end (Rx) of the transmitting/receiving section (12),
The make contact (a2) is connected to the transmitting end (Tx) of the transmitting/receiving section (12).
5. The communication control device according to claim 4, wherein the communication control device is a common of a relay (17) connected to a relay (17). 6. A transmitting/receiving unit (12) comprising a receiving end (Rx) that receives transmission data from the upstream side in the transmission direction, and a transmitting end (Tx) that transmits the transmission data to the downstream side in the transmission direction.
) in a communication control method for a secondary station in a loop transmission network in which a plurality of secondary stations each having a primary station and a loop line (18) are connected in a loop by a loop line (18), wherein power is not supplied to the secondary station. When the transmitting/receiving unit (1
The transmitting end (Tx) of 2) is cut off from the loop line (18), and the upstream and downstream loop lines (18) are connected to each other in the first state, and power is supplied to the secondary station. Then, time measurement is started, and the connections between the upstream and downstream loop lines (18) are cut off, and the downstream loop line (18) and the transmitting end (Tx) of the transmitting/receiving section (12) are cut off.
When the secondary station is operating normally, the clock value is cleared at regular intervals so that the clock value does not exceed a predetermined value, and the clock When the value exceeds a predetermined value, the state returns to the first state, disconnects only the secondary station, and disconnects the upstream loop line (18).
and a downstream loop line (18) are connected to each other to restore a loop transmission network.