JPH06311569A - Repeater for communications line and communication system - Google Patents

Abstract

PURPOSE:To provide bidirectional communication and unilateral communication. CONSTITUTION:A repeater 20 is the one arranged in the middle way of a serial communications line 3 on which the bidirectional communication is performed, and to amplify communication data in bidirectional communication, and it is provided with first reception and transmission circuits 22R, 22T, second reception and transmission circuits 23R, 23T, and dip switches DP1, DP2. The first reception and transmission circuits 22, 22 receive the communication data in a first direction, and outputs by amplifying it. The second reception and transmission circuits 23R, 23T receive the communication data in a direction opposite to the first direction, and outputs by amplifying it. The dip switches DP1, DP2 switch the communication direction of the first and second reception and transmission circuits in two way directions or one way direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system for connecting a host unit and a subordinate unit subordinate to the host unit, and a relay device that can be used in the system.

[0002]

2. Description of the Related Art In the case of a network system including a large number of terminals, a host computer, and a communication system for connecting them, such as a production control system, data attenuation on the communication system is prevented. In order to do so, a relay device (repeater) is used. As a communication system using this type of relay device, Japanese Patent Application Laid-Open No. 2-253
There is one disclosed in Japanese Patent No. 741. This communication system includes means for connecting / disconnecting the relay device to / from the power source, and the connection / disconnection control of the relay device enables connection / disconnection of the communication system without using a dedicated switching device.

When the communication system is constructed, a communication test for testing the actual data flow is performed. In addition, a communication test is also performed when a problem occurs in the communication system.
At the time of this communication test, a line monitor is connected between the relay unit and the host unit arranged at the end of the communication line. The line monitor records commands and data sent and received between the device and the host unit, and transfers the recorded commands and data in response to a request from the host unit. The administrator of the communication system checks the contents of commands and data transferred to the host unit and debugs them.

During the communication test, the data from the line monitor is sent only to the host unit, not to the device connected to the communication line. Communication is needed. However, since the power supply is turned off in the above-mentioned conventional configuration, unidirectional communication cannot be realized. Therefore, the conventional configuration cannot easily obtain the communication test environment.

An object of the present invention is to realize bidirectional communication and unidirectional communication. Another object of the present invention is to enable easy switching to a communication test environment.

[0006]

A relay device according to the present invention is a device which is arranged in the middle of a communication line for bidirectional communication and amplifies bidirectional communication data. A path, a data transmission path in the second direction, a blocking means, and a switching means are provided. The transmission path in the first direction is for transmitting data in the first direction. The data transmission path in the second direction is for transmitting data in the second direction which is the reverse of the first direction. The shutoff means includes a first direction and a second direction.
It is provided in the directional data transmission path and blocks data transmission respectively. By the blocking means, the communication direction can be switched to bidirectional or unidirectional.

A communication system according to the present invention is a system for connecting a host unit and a subordinate unit subordinate to the host unit,
A communication line, a relay unit, and a line monitor unit are provided. The communication line performs bidirectional communication between the host unit and the subordinate unit. The relay unit is arranged in the middle of the communication line, the communication direction can be switched to bidirectional or unidirectional, and amplifies and outputs the received communication data. The line monitor unit is connected to the communication line between the relay unit and the host unit.

[0008]

In the relay device according to the present invention, when the data in the first direction is received, the data is transmitted through the first transmission path. When receiving the data in the second direction, the data is transmitted through the second transmission path. When either one of the blocking means blocks, the communication direction is switched to the unidirectional communication direction, and the unidirectional transmission path is established.

Here, since the communication direction can be switched between bidirectional and unidirectional, bidirectional and unidirectional communication can be realized. In the communication system according to the present invention, bidirectional communication is performed between the host unit and the subordinate unit via a communication line. In addition, a relay unit is arranged in the middle of the communication line to amplify and output the received data.

Here, for example, when the communication direction of the relay section is switched from the dependent section to the unidirectional direction only on the host side during a communication test or the like, the output data from the line monitor does not go to the dependent section. On the other hand, the communication data output from the subordinate unit can be sent to the line monitor unit. Since unidirectional communication is possible here, it is possible to easily switch to a communication test environment during a communication test or when trouble occurs.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a production management system adopting an embodiment of the present invention comprises a host computer 1 and N (for example, 16) connected to the host computer 1 through a line controller 2 and a serial communication line 3. Individual terminals 4 ₁ to 4 _N. Facilities 5 _{1 to} 5 _N are separately connected to the terminals 4 ₁ to 4 _N , respectively.
For example, the equipments 5 _{1 to} 5 ₄ are press machines A to D, the equipment 5 ₅ is a die cast machine, the equipments 5 ₆ and 5 ₇ are labeling machines A and B, and the equipments 5 _{N-2 to} 5 _N are packing machines A to C. Is. The terminals 4 ₁ to 4 _N acquire the production management data from the connected equipments 5 _{1 to} 5 _N by classifying them into products. The production management data includes data such as equipment start / stop, stop factors, defective factors, the number of productions, and defective product detection. It also includes product data such as product type and lot number.

The host computer 1 totalizes and outputs the production control data collected by the terminal 4. The host computer 1 is, for example, a personal computer,
It has a computer body 6, a display 7, a keyboard 8, a mouse 9 and a printer 10. The line controller 2 is connected to the RS232C interface (not shown) of the host computer 1.

The serial communication line 3 is a line capable of bidirectionally communicating communication data, and can transmit communication data in two kinds of high and low communication modes (for example, 625.0 kHz and 312.5 kHz). Host computer 1 to terminal 4
Communication data sent to the host computer 1
It includes various terminal setting data set in. Also,
Communication data communicated from the terminal 4 to the host computer 1 includes production management data and processed data obtained by processing the production management data. The character length forming the data of these communication data is constant regardless of the type of data. Further, the communication data is differential Manchester encoded data, and has a header section indicating the beginning of a character, a data section, and a footer section indicating the end of the character. The header part is a 2-bit fixed code.

A repeater 20 for preventing attenuation of communication data is arranged in the middle of the serial communication line 3. The repeater 20 is arranged, for example, at every predetermined distance and every predetermined number of the serial communication lines 3. The relay 20 is also disposed between the terminal 4 ₁ and the line controller 2 of the most upstream side. The line monitor 11 is connected to the communication line 3 between the repeater 20 and the line controller 2.
Are connected. The line monitor 11 is for accumulating communication data communicated on the line 3. As the line monitor 11, one of the terminals 4 of the facility 5 may also be used.

The repeater 20 has a main body case 12 as shown in FIG. Two communication connection parts 1 for connecting the communication line 3 are provided on the upper side of the main body case 12 in FIG.
4, 15 are arranged. Further, in the vicinity of the communication connection parts 14 and 15 of the main body case 12, the communication connection parts 14 and 15 are provided.
Corresponding to, the indicators 24 _a , 24 for indicating the communication direction
_b is located. The indicator 24 _a, 24 _b has, for example, a LED. A power supply connecting portion 16 is arranged on the lower side of the main body case 12 in FIG. Power connection 1
Corresponding to No. 6, a power supply indicator 25 indicating whether or not the power is turned on is arranged. An 8-bit DIP switch unit 13 for making various settings is arranged on the left side of the main body case 12 in FIG. The DIP switch unit 13 is normally closed by a door 17. In the DIP switch unit 13, the first bit DIP switch DP1 and the second bit DIP switch DP2 are for switching the communication direction between bidirectional and unidirectional.

Further, the repeater 20 has a control section 21 for selectively controlling communication and display, as shown in FIG. The repeater 20 receives a signal through the serial line 3 such as communication data encoded into noise and pulse signals in the direction of the arrow R and outputs the signal to the control unit 21 and a first receiving circuit (RC1) 22 _R , First transmission circuit (TC1) 22 _T for amplifying and outputting communication data output from the control unit 21
And a second receiving circuit (RC2) 23 _R that receives a signal in the direction of the arrow L and outputs the signal to the control unit 21, and a second transmitting circuit (T that amplifies and outputs the communication data output from the control unit 21.
C2) 23 _T , a pair of indicators 24 _a and 24 _b composed of LEDs for displaying the communication direction of communication data, and NA
And a ND gate 26 _a, 26 _b.

NAND gate 26_a, 26_bOne input end
Are connected to the control unit 21. The other input end is
It is connected to the power supply terminal section 16 via a resistor and
Grounded via the IP switches DP1 and DP2.
Has been. NAND gate 26_a, 26_bThe output end of
First and second transmission circuit 22_T, 23_TAnd indicator 2
Four _a, 24_bConnected to and respectively. Control unit 21
To the first and second transmission circuits 22_T, 23_TIn the NAN
D gate 26_a, 26_bTransmission permission signal ENT via
1 and ENT2 are given respectively. This transmission permission signal
ENT1 and ENT2 are display 24_a, 24_bAlso give
To be

The control unit 21, as shown in FIG.
It has second waveform shaping sections 32 _a and 32 _b , first and second edge detection sections 33 _a and 33 _b, and a logic control section 31. The first and second waveform shaping sections 32 _a and 32 _b are composed of digital low pass filters for removing high frequency noise of communication data received by the first and second receiving circuits 22 _R and 23 _R. First and second edge detector 33
_a, 33 _b is, first, is for detecting the trailing edge of the communication data received by the second receiver circuit 22 _R, 23 _R.

The outputs of the first and second waveform shaping sections 32 _a and 32 _b are given to the shift register 34. The shift register 34 delays the waveform-shaped communication data for a predetermined time. This delay time is set so as to match the header section detection time of the logic control section 31 described later. The shift register 34 has a changeover switch for switching the input / output between the first channel and the second channel, and the first channel is for the first waveform shaping section 32 _a and the first transmission circuit 22 _T , The second channel is the first
It is for the waveform shaping section 32 _b and the second transmission circuit 23 _T.

[0020] The first, second edge detection unit 33 _a, 33 _b
Is output to the counter A35 and the logic control unit 31. The counter A35 includes the first and second edge detectors 3
3 _a, 33 _b is detected by the edge interval of is intended to measure respectively, it is cleared each time the edge is detected,
Start counting. The counter A35 compares the count value with the preset value and gives the comparison result to the logic control unit 31. In the counter A35, two types of long and short cycle data relating to the header section, which are determined according to two types of communication speeds (communication frequencies), are held as preset values.

The logic control section 31 is composed of a logic circuit having a hardware configuration, determines which edge detection section has detected the edge, and of the counter A35 from the detected edge to the next detected edge. Based on the comparison result, it is determined whether or not the header portion of the data is included between the edges, and the presence or absence of the data is determined. When it is determined that there is data, the transmission permission signals ENT1 and ENT2 for permitting the transmission are selectively output to either one of the first and second transmission circuits 22 _T and 23 _T. Further, the logic control unit 31 outputs a channel switching signal to the shift register 34 depending on which edge detection unit has detected the edge.

A counter B36 is also connected to the logic controller 31. The counter B36 has a transmission permission signal ENT.
1, to determine the ON time of ENT2. Here, since the character length of the communication data is constant, the counter B36 calculates the time for each constant character length according to the two types of communication speeds. Next, the operation of the above-described embodiment will be described according to the control flowchart shown in FIG.

The communication data handled here is
This is data encoded by the differential Manchester encoding system shown in FIG. This communication data is converted into the signal shown in FIG. 6B or 6C by the receiving circuits 22 _R and 23 _R. In the differential Manchester encoding method, in the communication data consisting of "01" or "10", the same communication data as the previous communication data is code "0", and different communication data is code "1". Will be decrypted. Therefore, the header portion including the code “10” becomes communication data “100101” or “011010” as shown at the beginning of FIG. 6B or 6C, and the edge interval thereof is 1.5. Become a clock. The time of the clock number is preset in the counter A35. Further, the maximum edge interval is 2 clocks as shown in FIG. 6 (B), and the counter A35 is 2 clocks in the low speed communication mode.
When counting the time that exceeds the clock, it overflows.

The logic control section 31 first starts the counter A35 in step S1. In step S2,
Wait for counter A35 to overflow. The reason why the counter A35 waits for the overflow is to determine whether or not the communication data has been input midway. That is, when the communication data is in the middle, the maximum edge interval Tmax of the communication data is 2 clocks.
Does not overflow.

When the counter A35 overflows, the process proceeds to step S3. In step S3, the first edge detection unit 33 _a determines whether or not the edge is detected, further in step S12, the second edge detection unit 33 _b determines whether or not the edge is detected. When an edge is detected in step S3, the process proceeds to step S4. In step S4, the channel is set to 1. This allows
The input / output of the shift register 34 is switched to the first channel side, and the shift register 34 and the first transmission circuit 22 _T are connected. In step S5, the counter A35 is started. Here, the reason why the counter A35 is started is to detect the header portion added to the head of the communication data. In step S6, it is determined whether the counter A35 has overflowed. Here, it is determined whether or not the received data is noise depending on whether or not the counter A35 overflows. In other words, in the case of instantaneous noise, the counter A35 overflows because the next edge is not input even if one edge is input. Therefore, if it is determined in step S6 that the counter A35 has overflowed, it is determined that the input signal is noise, and the process returns to step S3.

Until the counter A35 overflows, the process proceeds from step S6 to step S7. In step S7, the first edge detection unit 33 _a determines whether or not it is detected again edge. While the edge is not detected, the process returns to step S6. When the first edge detection unit 33 _a detects an edge in step S7 before the counter A35 overflows, the process proceeds to step S8a.
In step S8a, from the comparison result of the counter A35 when the edge is detected, the high speed communication mode (625.0k
It is determined whether or not the header part at (Hz) has been detected. Thereby, the presence or absence of communication data at a high communication speed is determined. The delay time of the shift register 34 is set to the time until the header portion is detected at this time.

When the header portion of the communication data in the high speed communication mode cannot be detected in step S8a, the process proceeds to step S8b. In step S8b, it is determined whether the header portion of the communication data in the low speed communication mode (312.5 kHz) is detected from the comparison result of the counter A35 when the edge is detected. Thereby, the presence or absence of communication data at a low communication speed is determined. Step S
When the header portion of the communication data cannot be detected in 8b, it is determined that the noise is not the communication data but the process returns to step S1. In addition, step S8a or step S8
When the header portion is detected in b and it is determined that the data is communication data, the process proceeds to step S9a. This step S8
The presence or absence of communication data and the communication speed thereof can be determined depending on which of a and step S8b the header is detected.

In step S9a, the transmission permission signal ENT1 in the counter B36 is determined according to the determined communication speed.
Set ON time of. This on-time is set to be twice as long when the speed is low as when the speed is high. Step S9b
Then, the counter B36 is started, and the transmission permission signal E
Turn on NT1. As a result, the first transmission circuit 22 _T amplifies and outputs the communication data delayed by the shift register 34. Also, LED indicator 24 _a is turned on.

When the DIP switch DP1 is on, the output of the NAND gate 26a is off, so the transmission permission signal ENT1 is off. Therefore, even if the communication data is received, it is not output. In this case, it is possible to realize unidirectional communication in which only the second receiving circuit 23 _R and the second transmitting circuit 23 _T operate. In step S10, the end of the counter B36 is waited for. As described above, the counter B3
6 is for measuring the communication time of a constant character length according to the data communication speed. When the counting of the counter B36 is completed, the process proceeds to step S11. Step S
In 11, the transmission permission signal ENT1 is turned off, and step S
Return to 1. As a result, the communication data output of the first transmission circuit 22 _T is completed, and the LED of the display 24 a is turned off.

On the other hand, if it is determined in step S12 that the second edge detector _33b has detected an edge, the process proceeds from step S12 to step S13. Step S13
The operation in step S18b is almost the same as the operation in step S4 to step S9b, and thus the description thereof is omitted.
The channel is set to 2 in step S13. As a result, the shift register 34 and the second transmission circuit 2
3 _T is connected.

Here, the header section is detected at the high speed communication speed or the low speed communication speed based on the edge detected on the side of the second edge detection unit 33 _b , and it is determined whether or not the data is communication data. When it is determined that the data is not noise but communication data, the counter B36 is started in step S18b,
The transmission permission signal ENT2 is turned on. As a result, the second transmission circuit 23 _T amplifies and outputs the communication data delayed by the shift register 34. Also, LE of the display 24 _b
D lights up.

When the dip switch DP2 is turned on, the output of the NAND gate 26b is turned off.
The transmission permission signal ENT2 is turned off and is not output even if the receiving circuit 23 _R receives communication data. In this case, unidirectional communication in which only the first receiving circuit 22 _R and the first transmitting circuit 22 _T operate can be realized. Also, the DIP switch DP
When both 1 and DP2 are turned on, the repeater 20 is disconnected. Therefore, the system can be switched.

When the process in step S18 is completed, the process proceeds to step S11 via step S10. In step S11, the transmission permission signal ENT2 is turned off, and the process returns to step S1. As a result, the output of the communication data from the second transmission circuit 23 _T is completed, and the LED of the display 24 _b is turned off.
Here, since the transmission enable signals ENT1 and ENT2 are switched on and off by the dip switches DP1 and DP2, bidirectional communication and unidirectional communication can be realized.
Further, by turning on both the DIP switches DP1 and DP2, the communication can be cut off. Therefore, it can be used as a circuit breaker for turning on both of them when switching communication, and for turning on one of them as a unidirectional repeater when debugging a communication system.

When testing the communication system, all the commands and data of each terminal are stored and the communication line is checked. At this time, the communication direction of the relay 20 is switched to the communication direction to the host computer 1 side. Then, even if a command is sent from the host computer, it is not sent to the terminal 4 but only to the line monitor 11. The line monitor 11 stores the communication data sent from the terminal 4, and transfers the stored data only to the host computer 1 when the test is completed. The system administrator can check the transferred data to debug the communication line.

When performing such a communication test, the repeater 2
Since 0 can be switched between bidirectional and unidirectional, a test environment can be easily realized. Other Embodiments (a) In the above embodiments, the dip switch was used to switch the communication direction, but an analog switch may be used. In this case, the analog switch can be turned on / off by communication data. (B) In the above embodiment, the control is performed by the hardware configuration, but if the communication speed is low, the control may be performed by the soft fair. (C) Instead of the DIP switch, bidirectional or unidirectional communication may be switched by a signal from a memory or a flip-flop. (D) A logic control unit may be provided for each communication direction, and communication control such as communication direction and noise removal may be performed by exchanging signals between the two logic control units.

[0036]

Since the relay device according to the present invention is provided with the blocking means for blocking the transmission path and switching the communication direction,
Bidirectional and unidirectional communication directions can be easily realized. In the communication system according to the present invention, since the relay unit can switch the communication direction to bidirectional or unidirectional, the relay unit can be unidirectional during the test and bidirectional during the actual operation. Therefore, the test environment can be easily realized.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a production management system that employs an embodiment of the present invention.

FIG. 2 is a plan view of a repeater.

FIG. 3 is a block configuration diagram of a repeater.

FIG. 4 is a block configuration diagram of a logic control unit.

FIG. 5 is a control flowchart of a logic control unit.

FIG. 6 is a diagram showing an example of communication data.

[Explanation of symbols]

3 serial communication line 13 DIP switch 20 repeater 21 logic control unit 22 _R , 23 _R receiving circuit 22 _t , 23 _t transmitting circuit 26a, 26b NAND gate

Claims (2)

[Claims] 1. A communication line relay device, which is arranged in the middle of a communication line for bidirectional communication and amplifies bidirectional communication data, comprising: a data transmission path in a first direction; and a first direction. A reverse data transmission path in the second direction, and a blocking means provided in the data transmission paths in the first direction and the second direction for blocking the data transmission respectively, the bidirectional or bidirectional communication direction is provided by the blocking means. Communication line relay device that can be switched in one direction. 2. A communication system connecting a host unit and a subordinate unit subordinate to the host unit, the communication line performing bidirectional communication between the host unit and the subordinate unit, and the communication line. Connected to the communication line between the relay unit and the host unit, the relay unit being disposed in the middle of the communication direction, capable of switching the communication direction to bidirectional or unidirectional, and amplifying and outputting the received communication data. And a communication system including: