JPH0325062B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is designed to remotely receive transmitted signals from a central control device (center device) serving as a main body, and output the signals to an output target device such as a large display device. The present invention relates to a transmission control method in a system consisting of a terminal that outputs an output to a center device and inputs and transmits an operation signal to the center device. This type of method not only enables a system to be configured at a low cost, but also allows the displayed content as output data from the terminal to be updated more quickly, and the operation content of the operation switch input to the terminal to be transmitted to the center equipment more quickly. It is desirable that the contents of the information be transmitted reliably.

[Prior art]

There are various transmission control methods in this type of system for centrally monitoring and controlling terminals located far from a center device, and it is difficult to generalize about conventional methods. However, from the perspective of standardization, the transmission methods themselves are as follows: 1) The hardware standards are the RS232C method for serial transmission, the GP-iB method for parallel transmission,
There are current loop methods for serial transmission, etc., and 2) In addition, there are various transmission procedures such as synchronous methods and asynchronous methods as software standards.

[Problem to be solved by the invention]

However, these methods must be highly reliable for a variety of general-purpose applications;
The reality is that this is dealt with by increasing redundancy in principle. For this reason, there is a problem in that the manufacturing cost of the system inevitably increases in terms of both hardware and software.

Also, in terms of transmission speed, it is possible to perform high-speed transmission coupling between a center device and terminals or between terminals using various transmission techniques. For example, in optical transmission systems using optical fibers,
High-speed data of 1Mbit/sec to 10Mbit/sec is actually used, so for example, to simply transmit 100bit data twice, 100bit/1Mbit/sec =
Transmission is possible at an extremely high speed of 0.1ms.

Although the optical transmission method is high-speed as described above, it also has the problem of being economically expensive.
In terms of actual applications, there are many uses for monitoring the operating status of equipment at remote locations, controlling the ON/OFF of remote loads, and transmitting voltage and current. For purposes of monitoring and controlling such equipment, it is not necessarily necessary to have the speed of optical transmission; it is sufficient to have a reaction speed that does not feel unnatural when actually operated by a human. Moreover, it must be inexpensive to be suitable for practical use.

Conventionally, for such fields, a number of inexpensive transmission methods have been used, such as transmission using mechanical filters and carrier waves carried on power lines, but each method has its advantages and disadvantages. For example, in a method using a mechanical filter, the number of transmission channels (corresponding to signal bits) is limited to several dozen types, and the transmission time is also disadvantageous in that it requires a transmission time of about 0.2 to 0.5 seconds. In addition, in the power line carrier method, the power line also serves as a signal line, so construction is easy, but there is also the problem of noise generated by the carrier wave, and since signals are generally sent in synchronization with the commercial frequency, the amount of data transmitted is limited. There is also the problem of limitations.

There are various other systems that utilize dedicated signal lines for facilities, but the current situation is that they are configured to suit each purpose. In other words, there is no particular standard method, and various dedicated transmission systems are created depending on the purpose. However, these dedicated transmission systems are currently unsatisfactory in terms of functionality and cost.

The transmission method of the present invention, except for the above-mentioned drawbacks, has been devised as a method suitable for a dedicated system, independent of the above-mentioned standard method, and meets the following requirements: 1) Large number of remote displays It is possible to transmit signals given to an output target device such as a device via a terminal from a center device using simple equipment.

2) Ability to faithfully transmit changes in input signals caused by operation switches, etc. on the remote terminal side within limited transmission speeds, and to respond quickly.

3) The system configuration is simple, inexpensive, and highly reliable.

4) To reduce the burden on the center device's functions as much as possible.

The purpose is to provide a transmission control method that can satisfy the following requirements.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a center device 1 and a plurality of terminal devices 300 to 30 respectively connected to the center device via lines.
As a communication cycle with n, the center device specifies a terminal device and sends an output command 331 to control the output target device connected to the specified designated terminal device.
1, T2, the center device specifies a terminal device and outputs a data output command 312, and receives input data 342 from the input device connected to the specified terminal device to be sent from the specified terminal device to the center device. A cycle T3 is provided, and when the center device determines that there is no need to send input data from the terminal device, the transmission cycle is executed, and when the center device determines that there is a need to send input data from the terminal device, the center device executes the transmission cycle. In a transmission control method in which a receiving cycle is executed, signals 200, 201, 20 are sent by a center device to specify a terminal device in a communication cycle.
2, a priority communication request signal 321 that requests the center device to send the input data for each address of the specific terminal device in response to a change in the input data to the specific terminal device to be prioritized; and the specific terminal device. Or a terminal device other than a specific terminal device, in response to a change in input data to a designated terminal device that is a terminal device designated by the center device during its transmission cycle or reception cycle. A self-terminal communication request signal 322 in which the designated terminal device itself requests data transmission; and a corresponding input to the center device in response to a change in input data to other terminal devices other than the designated terminal device and the designated terminal device. A common communication request signal 323 that requests data transmission from the other terminal device regardless of the address of the other terminal device.
and, when a priority communication request signal is detected, the center device executes the reception cycle in a predetermined order with the specific terminal device that sent the priority communication request signal, and then receives the common communication request signal. When detected, other terminal devices are sequentially investigated in a predetermined order following the reception cycle of the specific terminal device that sent the priority communication request signal and the designated terminal device that sent the self-terminal communication request signal. After finding another terminal device that sent the common communication request signal and executing a reception cycle with this terminal device, if the own terminal communication request signal is detected, the designated terminal that sent this own terminal communication request signal If the device is a specific terminal device, it is assigned an address higher in rank than the specific terminal device and sends out its own terminal communication request signal in the order following the reception cycle with the specific terminal device that sent the priority communication request signal. If the designated terminal device is a terminal device other than the specific terminal device, the designated terminal device that sent the own terminal communication request signal and the reception cycle in the order following the reception cycle with the specific terminal device that sent the priority communication request signal. After executing, the communication cycle (reception cycle or transmission cycle) returns to the next one, and each terminal device functions as a transmission/reception buffer that temporarily stores the data 331 received from the center device or the data 342 to be sent to the center device. The first storage area Y1 of
and input data 34 sent from the terminal device to the center device in the previous reception cycle of the terminal device.
2, and one or more storage areas that store change data corresponding to changes in time series of input data after input data Y2a stored in the second storage area Y2. A data retransmission system comprising a storage means having third storage areas Y3 and Y4, and a data transmission command from the center device requests retransmission of the input data sent from the terminal device to the center device in the previous reception cycle. If it is a send command, the input data Y2a = 342 stored in the second storage area is sent to the data send command from the center device after the data sent from the terminal device to the center device in the previous reception cycle. When the next input data transmission command requests the transmission of input data, the data Y2a stored in the second storage area is changed to the change data Y3a stored in the third storage area,
Correct the data based on the oldest data Y3a of Y4a and store it in the second storage area as new input data Y2a, and input the newly stored input data Y2a in this second storage area to the respective first storages. Each time the input data stored in the second storage area is modified, the oldest change data Y3a stored in the third storage area is set to the next oldest change data Y3a. I replaced it with change data Y4a.

[Effect]

If the above technical means causes a change in the input data to the terminal device and it becomes necessary to send the latest input data to the center device, if this terminal device is a specific terminal device that should be prioritized. is a priority communication request signal 321 for each address assigned to a specific terminal device, and if the terminal device is a specific terminal device or a terminal device other than the specific terminal device, and the terminal device is a specific terminal device or a terminal device other than the specific terminal device, and it is sent from the center device in the communication cycle (transmission cycle or reception cycle). If the terminal device is the designated terminal device, or if the terminal device currently executing the reception cycle has input data that cannot be sent in the reception cycle, the own terminal communication request signal 322 is sent to the terminal device. is a terminal device other than the specific terminal device and the designated terminal device, the common communication request signal 323
are sent to the center device from the terminal device whose input data has changed, and the center device that receives these communication request signals performs the communication according to the priority order assigned in advance to the terminal device that sent these communication request signals. In addition, a large number of terminal devices are assigned to a small number of communication request bits by skipping terminal devices that have not sent a communication request signal and sequentially specifying terminal devices that have sent a communication request signal and performing a reception cycle. Changes in input data on the terminal device side are made to follow the priority of that terminal device, and changes in input data from terminal devices with lower priority can also be sent to the center device as quickly as possible. , the responsiveness and transmission efficiency of the transmission system as a whole can be improved.

In addition, in the terminal device, the input data first input from the input device (key read data) or the input data sent to the center device is stored in the second storage area as it is, and from the input device thereafter. For the input data, only the change from the previous input data input from the input device is stored in the third storage area, and the data input from the input device after the data sent to the center device last time is stored in the third storage area. When transmitting the input data from the original input device, the input data stored in the second storage area is corrected by the change data stored in the third storage area. By restoring the data to the form and sending it to the center device, once an error communication occurs, subsequent data will always contain an error amount, as in the case where only changes are transmitted. There has never been a problem with the reliability of the transmitted data, and changes in input data from input devices can be faithfully and reliably transmitted to the center device, and input data from terminal devices can be transmitted faithfully and with high reliability. Memory capacity for storage is saved.

〔Example〕

The present invention will be explained below based on FIGS. 1 to 7.
The same reference numerals in the figures indicate the same or corresponding parts.

FIG. 1 shows a configuration diagram of a terminal that performs such control. FIG. 2 shows a timing chart for communicating with a center device using this terminal. Figure 3 shows the communication format between the terminal and the center equipment, Figure A is the transmission format from the center equipment to the terminal, Figure B is the transmission format of the response from the terminal to the center equipment, and Figure C is the transmission format from the center equipment to the terminal. Figure D shows the data format of the output data to be sent to the center device, and Figure D shows the data format for transmitting the read result of the input signal at the terminal to the center device. Further, FIG. 4 shows the configuration of the system of the present invention, and FIG. 5 shows the configuration of the RAM in the center device. Further, FIG. 6 is a diagram showing an example of changes in key input signals (key read data) corresponding to slowness of key operations on the terminal and the timing at which the data is transmitted to the center device.
The figure shows part of the RAM map of the terminal.

In Fig. 4, 1 sends display data output to a display device outside the terminal (referred to as external) to the terminal, receives and stores input data input to the key matrix of the terminal, and performs necessary processing. This is a center device that has a function of transmitting the data as the display data. Reference numeral 2 denotes a signal transmission path connecting the center device 1 and a plurality of terminals, and here it is composed of two wires. 30, 300 to 30n are terminals in this system, the configuration of which is shown in FIG. That is, each terminal 30 has a one-chip microcomputer (hereinafter referred to as microcomputer) 32 as a central control device, and in addition to a communication circuit 31 for communicating with the center device 1 via the two-wire transmission path 2, External display device 37
A display output section 33 (this output section 33 can be switched between static output (latch output) and dynamic output) is used to display 64 points.An example of the most suitable use of this output section 33 is displayed. ), a test output unit 36 that performs static output such as display of 8-point test signals, and a key matrix 35 that reads ON/OFF operation inputs from 64 external key contacts 38; A test switch unit 39 includes a test switch for testing the operation of the microcomputer 32 in the terminal and an address switch for setting the address of the terminal, and decodes and displays the address signal output from the microcomputer 32 to the terminal. It has an output section 33 and a decoder 34 which supplies the key matrix 35. The test output section 36 displays status information based on the test switch and the address of the own terminal set by the address switch for confirmation.

Here, the configuration of the terminal 30 shown in FIG. 1 shows one example, and various methods can be used for output such as external display and input methods for external key contacts. Either method allows output from the microcomputer 32 to the outside, and the external signal can be output from the microcomputer 32 to the outside.
You should read it into .

In addition, although Figure 1 shows 64 points of display output and 64 points of key contact input, this means that there can be a considerable amount of output signals and input signals, so it is especially limited to 64 points. That doesn't mean it's true. The number of these input/output points can be determined depending on the application. Furthermore, although the display output is shown in FIG. 1, the display output section 33 may be used for purposes other than display, such as driving a relay to sound a buzzer or drive a motor, depending on the purpose. can.

Here, as the microcomputer 32, for example, a general-purpose microcomputer type 8085 can be used instead of the one-chip microcomputer described above, but in that case, it is necessary from an economic point of view to use as little data RAM as possible effectively. be. In other words, it is important to use the limited RAM capacity effectively and efficiently for transmission.

Now, such a terminal 30 (300 to 3 in Fig. 4)
0n) output to various external loads such as display for each terminal based on the data transmitted from the center device 1. At the same time, the contact input signal connected to the terminal is read, and when a change occurs in the contact input signal, the contact input status is transmitted to the center device 1.

A timing diagram of such communication between the center device 1 and the terminal 30 is shown in FIG. In the figure, 200, 201, 202 are 20-bit terminal address data transmitted from the center device 1 to the terminal 30, and 210, 211 are terminals specified by the terminal address designation data 200, 201 and other terminals. 8-bit terminal response data returned from the terminal 30 to the center device 1, 220, 22
1 is 73-bit display output data transmitted from the center device 1 to each designated terminal 30 as data for display, and 232 is a terminal whose contact input signal has changed as described later. Based on the terminal response data 211 including the communication request signal,
This is terminal input data sent to the center device 1 from the terminal 30 designated by the center device 1 by the terminal address designation data 202, and is 80-bit data including key read data input to the terminal 30. However, the terminal input data 232 includes a communication request signal from a terminal other than the terminal whose contact input signal has changed, and the terminal response data 232
It also includes partial data (terminal response data section 341) that has the same purpose and structure as those of 0 and 211, which will be described later.

Here, each terminal address specification data 200, 20
T1, T2, determined by the beginning of 1,202,
The period T3 is called a communication cycle, and when communication cycles T1, T2, and T3 are called separately,
In each of these communication cycles, the center device 1 transmits or receives data to or from the terminal specified by the terminal address designation data 200, 201, and 202 (i.e., the display output data 220, 2).
21 or terminal input data 232), and the former is called a transmission cycle, and the latter is called a reception cycle.

Further, FIG. 3A is a format showing the 20-bit configuration of the terminal address designation data 200, 201, 202, etc. in FIG. 2, and 310 is a start bit,
311 is an address, 312 is a command, 313,
Reference numeral 314 indicates an inverted address and an inverted command obtained by inverting the numerical values of the address 311 and command 312 (this is one of the methods for improving the reliability of addressing, which is called so-called inverted double transmission).

Figure 3B is the terminal response data 210, 21 in Figure 2.
The format shows the 8-bit configuration of 1,...
This configuration is shown in Figure 2, terminal input data 232,...80
It has exactly the same structure as the start bit 340 and terminal response data section 341 in the format of FIG. 3D showing the bit structure, and has the same purpose. Here, 321 is a priority communication request bit, 3
22 is an own terminal communication request bit, 323 is a common communication request bit, and 324 is a terminal transmission data abort signal. The reason why the terminal response data section 341 is included in the terminal input data 232, . . . in this way is that regardless of the transmission cycle or reception cycle, if there is a change in signal input (change in key contact input) at any terminal, , as soon as possible from that terminal to the center device 1.
This is to make it possible to request the transmission of key reading data. When the center device 1 receives requests for this communication from multiple terminals, the center device 1 handles the terminals in a manner suitable for the purpose of the system, depending on whether the communication is to be carried out as described later, or depending on the priority of the terminals. is specified and the reception cycle begins, but in general, communication is often performed in the order of addresses within the same priority.

Figure 3C is Figure 2 display output data 220, 22
The format shows the 73-bit configuration of 1,...
330 is a start bit, 331 is display data,
332 and 333 are parities.

The first 8 bits of the 80 bits of the terminal input data in FIG. 3D have been described above, and the remaining part 342 is key read data, and 343 and 344 are parity. The signal from the center device 1 is read simultaneously by a plurality of terminals 300 to 30n, but since an address is assigned to each terminal,
Terminal address designation data 200 in FIG.
Using the addresses 201 and 202 (A311 in Figure 3), the center device 1 specifies the address of the terminal to communicate with, and also sends the command (A31 in Figure 3).
2) specifies the type of data to be subsequently communicated. This 20-bit terminal address designation data is stored by the center device 1 in the data format shown in FIG.
and command 312 are inverted data 313 and 314 of those addresses 311 and command 312, respectively.
It is also transmitted to all terminals 300 to 30n. Display output data 220 or 221 in FIG. 2 is displayed only on the terminal 30 that matches the data of this address 311.
is received, and terminal input data 232 is similarly transmitted only from the terminal 30 to the center device 1. The data format of this display output data 220 or 221 has the format shown in FIG. parity 333) is given.
The parity data 332 and 333 are created as horizontal and vertical parity in units of 4 bits, and this creation method was developed in Japanese Patent Application Laid-Open No. 59-1995 by the applicant.
It has already been specified in No. 62238 "Error checking method in multiplex transmission system". Along with checking the start bit 330, the display data 33
1 and its parities 332 and 333 is confirmed, the received data is correct, and the corresponding terminal 30 can output and display it on an external display device (37 in FIG. 1) according to the content of the received data. can.

Next, various methods can be considered as to how the center device 1 completes and repeats all transmission and reception (referred to as a total communication cycle) with each terminal 300 to 30n, depending on the nature and purpose of the system. .
An example of a typical total communication cycle is as follows: 1) The same weight is given to the display output and the terminal input, and after sending and receiving with the same terminal 30, the same communication with all terminals 300 to 30n is performed ( 2) A method in which display output is the main focus and there are few changes in the terminal input (a) A method in which the signal input to the terminal is performed manually, and the operation is performed more frequently. Since this is rarely done, it is not always necessary to notify the center device of the signal input status of each terminal every time it communicates with that terminal. The disadvantage of adopting a method in which the center device receives signal input from the terminal in question for each communication is that it communicates with the same frequency with both terminals whose signal input changes little and with terminals whose signal input changes rapidly. Since there is a possibility that changes in input from a terminal may be missed, it is necessary to increase the communication speed in order to prevent this without changing the communication method, which increases the equipment cost of the system.

For convenience of the following explanation, this method will be further explained in detail. Returning to FIG. 2, the center device 1 sends terminal address designation data 200 to call one terminal 30, obtains terminal response data 210, which will be described later, from that terminal and other terminals 30, and calls those terminals 30.
When it is determined that the terminal does not have new data (key read data) to be transmitted to the center device 1, the display output data 220 is sent to the terminal 30 in question, and communication cycle T1 (transmission cycle) with that terminal is performed. After that, the center device 1 specifies the next terminal 30 in a predetermined order using the terminal address designation data 201, obtains the terminal response data 211 in the same manner as above, and
Display output data 221 is sent and communication cycle T2
(transmission cycle) ends. Here, if it is found from the terminal response data 211 that there is new key reading data in the terminal in question or other terminals 30, the center device 1 uses the terminal address designation data 211.
2 specifies the terminal 30 having new key read data as described later, receives the terminal input data 232 from this terminal 30, and ends the communication cycle T3 (reception cycle). The format of the terminal input data 232 at this time is shown in FIG. 3D as described above, and in FIG. Parity 343 and 344 are added around data 342, and center device 1
It is sent back from the terminal to the center device 1 in accordance with the synchronization pulse sent from the terminal. Here, if the terminal response data part 341 in the terminal input data 232
If it is determined that there remains a terminal that has new key read data and is requesting transmission, the center device 1 either directly specifies the terminal as in the reception cycle T3, or temporarily performs scan communication as described below. After searching for it, in a reception cycle similar to the reception cycle T3, communication is made with the terminal that requested the transmission, and when communication with all terminals that have new key read data is completed in this way, the terminal address specification is performed again. The terminal 30 in a predetermined order following the data 201 is specified, and the transmission cycle T2 is
Execute the transmission cycle in the same manner as
, and thus executes the receive cycle with the next terminal in sequence.

That is, basically, the center device 1 sequentially designates the terminals 300 to 30n one by one in a predetermined order using the terminal address designation data 200, 201, . . . and provides display output data 220, 221, . Once the communication is finished, the transmission cycle continues again. If, in the middle of this transmission cycle, the terminal response data 211,... or the terminal input data 232 (the terminal response data section 341),
When it is determined that there is a terminal that has new key read data and is requesting communication, data input (receiving cycle) from all of the terminals is performed like an interrupt process, and then the basic Return to and continue the transmission cycle described above.

As mentioned above, this method uses the terminal response data 210, 211, ... and the terminal input data 2 in FIG.
32..., the center device 1 receives signal input only from the terminal 30 that needs to receive the signal input, and the terminal response data 21
This is illustrated by the format of 0.0,211 in FIG. 3B and the format of terminal input data 232 in FIG. 3D. The second to fifth bits (priority communication request bit 321) following each start bit 320, 340 in FIGS. This is a control signal bit assigned to each of the three terminals (also called priority terminals), and the center device 1 outputs "Low" with this bit.
A clock pulse of a signal (hereinafter referred to as L) is generated. In this control signal bit (priority communication request bit 321), only the priority terminal is assigned to the corresponding terminal in the priority communication request bit 321 in order to notify the center device 1 when there is a change in the key signal input of the terminal. It is possible to send an H signal back to the received bit.

Here, four terminals considered to be used frequently are specially selected from the viewpoint of effective use of signal bits, and are assigned to the second to fifth priority communication request bits 321. Note that the number of priority terminals does not need to be a specific number of four.

Here, the method by which the terminal returns the H signal is described in Japanese Patent Application Laid-Open No. 56-34256, "Data Transmission Method" by the present applicant.
It is easy to send notifications using the two-wire transmission method.

When an H signal is returned to the priority communication request bit 321, the center device 1 immediately returns the terminal (any one of addresses 0 to 3) that returned the H signal after completing the communication cycle with the terminal currently communicating. At this time, or if the H signal is returned from multiple terminals, the terminal usually uses addresses 0, 1, 2, 3, etc.
After the terminal which returned the H signal is designated in order of priority (0, 1, etc.) and the signal input is taken from the designated terminal and the reception cycle is completed, the normal transmission cycle is resumed.

Next, the 6th bit in the figure is the self-terminal communication request bit 322, which indicates that the terminal specified by the terminal address designation data 200, 201, 202 in Fig. If the specified data 200, 201, 2
This bit 322 is returned as an H signal in the terminal response data 210, 211 or terminal input data 232 following 02.

In this way, the terminal response data (210, 2
11), if this bit 322 is returned as an H signal, if the priority communication request bit 3
21 is H, the reception cycle with the priority terminal corresponding to that bit 321 is given priority, and then the reception cycle with the terminal whose own terminal communication request bit 322 is H is performed. (However, depending on the system requirements, it is also possible to continue communicating with the own terminal and then start communicating with the priority terminal.)

Next, the 7th bit in FIGS. 3B and 3D is a common communication request bit 323, which is returned as H when any terminal other than the priority terminal and the designated terminal has a new signal input. . In this case, after executing a reception cycle for the priority terminal and the designated terminal (however, if there are no corresponding terminals, the reception cycle is omitted), the new Other terminals having signal input are connected to the center device 1 by using the scan communication method described in Japanese Patent Application Laid-Open No. 58-130691, "Distant Monitoring and Control Method" by the present applicant.
(Therefore, the communication for this scan investigation (called communication request terminal confirmation communication)
is provided during the communication cycle), and after the reception cycle with the other investigated terminal is completed, the process returns to the basic transmission cycle.

Furthermore, the terminal transmission data abort signal 324 of the 8th bit in FIGS. If not, this bit is returned as H. Therefore, even if a terminal that has undergone a receive cycle is addressed again, if there is no change in the signal input to this terminal, this bit remains high and there is no need to perform another receive cycle after that receive cycle. It shows that there is no

Note that this terminal transmission data abort signal 324 can also be used for the scan communication by the center device 1.

3) A method in which the display output is the main component and there are few changes in the terminal input (b): After completing one cycle with each terminal 30 to 30n and the transmission cycle only, once every communication cycle,
A reception cycle is performed with all terminals whose key inputs (key read data) have changed, and in this reception cycle, the priority communication request bit 321, own terminal communication request bit 322, and common communication in FIGS. Request bit 323 is utilized.

4) A method that mainly uses terminal input; normally communication of key read data up to 64 is carried out cyclically for all terminals 30 to 30n as a reception cycle, and only when the center device 1 needs to output to the terminal 30. , in which transmission cycles are sequentially inserted as display output data communication. This method is suitable for systems that place emphasis on notifying the center device of key reading at high speed.

In addition to this, it is possible to set various total communication cycles on the center device 1 depending on the purpose of the system. It has an input communication function, and when communicating key read data with the center device, it sends out all the changes in the time series of each key input, and the center device can compare it with the previous data and find the changed key. Considering the noise that has a large effect on roads, this can be said to be a powerful means of increasing reliability.

Next, the functions of the center device 1 will be explained as follows. Figure 5 shows the inside of the center device 1.
A configuration diagram of RAM is shown. 12 is output RAM,
For example, if the output data such as the display of the terminal 30 is 64 bits, it has as many bits as the number of connected terminals, with 64 bits as one unit. Here, the number of terminals is assumed to be 16, so 16 units are built in, and the transmission cycle is sequentially repeated for all 16 terminals to output them cyclically.

On the other hand, 13 is a key input RAM for setting key input signals on the terminal 30 side, which are arranged in address order. This part of RAM13 is terminal 30
The state of the key contact signal is transmitted to the center device 1 and set by the process described above. Therefore, by determining changes in data in the RAM 13 within the center device 1, the center device 1 can know the progress of key contact operations on the terminal 30 or simply the comparison with previous data.
A center device 1 and a terminal 30 having such functions
By using , it is possible to easily process the data in the RAM inside the center device 1 and then output it to the terminal 30 at a distant point.
The output target device of this terminal 30 can be a display device 37 (FIG. 1) having a display panel, and more sophisticated control is also possible by using a buzzer, relay output, etc. in a part of the display device 37 (FIG. 1). In addition, it is possible to efficiently transmit and notify the state of the signal input through the terminal-side contact (which may be a semiconductor switch) to the center device, and when the center device 1 detects this remote switch operation. , the center device 1 executes the operation assigned to that switch, and the processing result is used as the output for the data to be displayed.
Since the data is input to the RAM 12 (FIG. 5), by receiving the data in the RAM 12 on the terminal side, the operation result can be known, for example, in the form of a centralized display control panel.

Next, a method for faithfully and quickly transmitting terminal input data while reducing the storage capacity of terminal input data, which is the main focus of the present invention, will be described in detail.

There are two transmission methods for transmitting the signal input status of a terminal. First, the state of signals in the terminal is always transmitted to the center device by access from the center device, or by the terminal itself starting communication with the center device. It is a method. The second method is to first notify the center device of the signal status of the terminal, and thereafter only notify the signal change status.

In the first method, the center device stores the signal state of the previous terminal in its memory, compares it with the signal state of the newly transmitted terminal, and can learn changes in the terminal's signal from the differences.

In the second method, since changes are transmitted from the terminal, the changes are added to the initially stored data and updated to always grasp the latest signal input status of the terminal. In this latter method, changes are accumulated based on the first communication data, so the amount of communication data is small and high-speed communication can be achieved as a result, but if even one error communication occurs, subsequent data will be Therefore, there will always be errors, and there will be no data correction function. This leaves problems with data reliability.

The method of the present invention retains the advantages of the first method and the second method, eliminates the disadvantages of the second method, simplifies the configuration of the terminal, and provides functions that are inexpensive and have no practical problems. This is what we are trying to provide.

Figure 6 shows the key input signal at the terminal 30.
Each timing when the ON/OFF change occurred,,
, is shown at what timing the information is transmitted to the center device 1. In the same figure, if A is quick to operate the key, B is
shows the same slow case. In addition, in each figure A and B, figure A shows the key input signal (key read data 342) based on the key operation on the terminal 30, that is, a time chart of ON and OFF of the key contact 38, and figure B shows the ON and OFF of the key contact 38. This is a communication cycle (receiving cycle) corresponding to T3 in FIG. Key input in the center device 1 that received the terminal input data 232
It shows changes in the ON/OFF data of the key contact 38 corresponding to Figure A, which is stored in the RAM 13.

Key contacts 3 of the terminal 30 at points A and B in each diagram.
8 is turned ON and the key contact 38 is turned OFF at a point, the point information is first transmitted to the center device 1 in each of the figures A and B, and then the point information is transmitted.

In this case, if the operation is slow as shown in FIG. 6B, the change in the key read data 342 at the timing shown in FIG. 6B is received by the center device at the timing shown in FIG. A change occurs in the key read data 342, and this change is also received by the center device at the timing shown in FIG. It is sufficient to have memory for one set corresponding to or, but if the key operation is fast as shown in Figure 6 A, the key read data at the timing A in the figure is received by the center device at the timing C in the figure. When the key input data of the terminal in question changes the timing,
In order to correctly convey the progress of this change to the center device, the terminal must
It is necessary to have four sets of memories to store two changes. Here, since the key read data at the timing shown in Figure A has already been sent to the center device, there is an idea that its memory can be erased, but as will be explained later, if the center device fails to receive it due to noise etc. Since it is necessary to transmit the key read data, it is necessary to store the four changes in ~.

The cost of a terminal is determined by the ability of the terminal to store data on the history of input changes in the terminal. Naturally, if a sufficient amount of RAM is built-in, the RAM and its control circuit will increase, which will impair practical cost performance. For this reason, as will be described later, in this embodiment, in addition to the memory area for the transmission and reception buffer, each terminal has a memory area for each key contact point to store the key read data sent to the center device in the previous reception cycle. area and two memory areas for chronologically storing change data indicating subsequent changes in the key read data, correct the key read data using the change data, and read the corrected key read data. This attempts to compensate for the lack of memory capacity by quickly transmitting data to the center device via a transmission/reception buffer.

That is, FIG. 7 shows a part of the RAM map in the RAM in the microcomputer 32 of the terminal 30. Figure A shows 4 units of RAM RU in each 16 columns.
Each unit RAM RU is composed of 4 bits as shown in Figure B, and therefore each row is
RAM (referred to as row RAM) Y1, Y2, Y3, Y4
has 64 bits, and each bit "column" (each 4 rows) corresponds to each of the 64 key contacts 38 of the terminal 30.

Row RAMY1, which serves as a transmission/reception buffer, is an area where display data 331 received from the center device 1 as communication RAM data Y1a is stored, and key read data 342 to be sent to the center device 1 is set. Therefore, the key read data 34
2, the transmission memory data Y2a, which is the key read data 342 stored in the row RAM Y2, is set in the row RAM Y1 and sent to the center device. In addition, row RAM Y3 and Y4 contain only the data (also called change marks) of the time-series changes after the transmission memory data Y2a (in row RAM Y2) of the key contact 38 corresponding to each bit column. Next transmission data Y3a (row RAM Y3
(inside), next transmission data Y4a (in row RAM Y4)
is remembered as.

Now, we will discuss what to do when the data transmission of the key read data 342 that changes in time series as shown in timing ~ in FIG. 6 is not correctly transmitted from the terminal 30 to the center device 1. Even if key input information is transmitted from the terminal to the center device, if a communication error occurs as a result of large noise being applied to the transmission line 2, the terminal cannot detect it.

For this reason, the center device has a communication monitoring function.
When a communication error with the terminal side (reception error at the center device) is detected from a mismatch in the parities 343 and 344 in Figure 3D or a defective data format, the next time you communicate with the terminal in question, the "Key Read" Command 3 in Figure 3 A to request "data retransmission"
12 and requests to send the same data as last time. If the communication is successful, a command requesting "send key read data" will be given, and new data will be sent.

If the terminal side fails to receive a command (command 312) from the center device, the same command is sent again because there is no data returned from the terminal.

As a result, if meaningless return data is generated from the terminal due to noise even though there is no response from the terminal, data that has already been communicated will be sent again due to the retransmission request from the center device. However, even in this case, since the data received by the center device is the same as the previously received data, the center device can ignore it without taking any particular action.

In this way, by providing the data retransmission function, it is possible to always automatically recover from various communication errors between the center device and the terminal, and to construct a highly reliable system.

Next, the movement of data in the RAM in the terminal 30 when the terminal 30 transmits the key read data 342 to the center device 1 will be explained with reference to FIG.

If the command 312 for "resend key read data" is given from the center device 1 to the terminal 30, the terminal 30 again sets the transmission memory data Y2a of the row RAM Y2 in the row RAM Y1 as the communication RAM data Y1a, and Key reading data 34
2 to the center device 1. Next, if there is a new request for "key read data transmission" from the center device 1, the transmission memory data Y2a in the row RAM Y2 is modified based on the next transmission data Y3a stored in the row RAM Y3, and this modified data is transmitted. The transmitted memory data Y2a is stored as new transmitted memory data Y2a in the row RAM Y2, and is also copied and set in the row RAM Y1, and sent as new key read data 342 to the center device.

At this time, the next transmission data Y4 of row RAM Y4
a is shifted to row RAM Y3 and then transferred to row RAM Y3.
Y4 is cleared to prepare for storing the new change mark.

In this way, the data in row RAM Y3, Y4 is
Since the change mark for the transmission memory data of RAM Y2 is stored, rows RAM Y3, Y4
If there is no change mark, the data in row RAM Y2 will match the data of the latest key input state of 64 points. As mentioned above, this change mark is placed on the same “column” of bits for each contact.
If the key input state differs from the data in row RAM Y2 for each bit column, first
Add a change mark to the corresponding bit of Y3, and if the key input state changes further, the corresponding bit of row RAM Y4 will be changed.
A change mark will be added to the bit. When modifying the transmission memory data Y2a of the row RAM Y2 based on the next transmission data Y3a, change the bit of the data Y2a corresponding to the presence of a change mark in the data Y3a, and change the bit of the data Y2a corresponding to the absence of a change mark in the data Y3a. Bit is not changed. The data Y2a corrected in this way is stored in the row RAM Y
Store in 2. If the RAM area is row RAM Y4
If there is only up to 2, the state change of key contact 38 is 2
Changes can be stored in memory, and changes beyond that will be ignored, but this is mainly determined by how much memory can be used.

When this change mark exists, the terminal 30 can set the 2nd to 5th bits in FIG. ,
If the terminal is communicating with the center device 1, the 6th bit in B and D in FIG. 3, that is, the own terminal communication request bit 322
can be set to "H" to request continued communication with the own terminal.

In this way, the key read data 342 on the terminal 30 side can be quickly transmitted to the center device 1. However, in this case, if the request for continued communication with the own terminal using the 6th bit (own terminal communication request bit 322) occurs, the center device 1 may A problem arises in that communication among the terminals 300 to 30n is monopolized by one terminal having the fast-changing key contact 38. This may be tolerable if it is simply a correct input signal change, but it is generally due to noise or element destruction.
Abnormal reactions may also result in incorrect change marks. From the viewpoint of system reliability, it is undesirable for the transmission path to be occupied by such an unexpected condition and data from other terminals to be no longer transmitted. The following method is used to prevent such abnormal communications.

1) The first method is to provide a counter on the terminal itself that stores the number of continuous communications, and count +1 for each communication cycle of the own terminal, and when the communication changes to another terminal, the counter is reset, For example, when the count value reaches 3 times, the transmission of the own terminal communication request bit 322 indicating a communication request with the own terminal is stopped (“L”).
) method.

2) The second method is that even if the terminal itself continues to request communication with its own communication request bit 322 set to "H", the center device will ignore it based on predetermined conditions. In this case, the function of the center device makes it possible to consciously reduce the number of communications with the terminal with the abnormal input, thereby maintaining the communications function with the rest of the system as a whole.

〔Effect of the invention〕

In this invention, dozens of signals are constantly sent cyclically from the center device to the terminal as display output, and the terminal receives these signals and reads the operation signal input from the outside, and if there is a change in this input signal, , has the function of notifying the center device of the occurrence of the above-mentioned signal input change and notifying the center device of the signal input status (key read data) upon receiving specification from the center device, and also has the function of notifying the center device of the signal input status (key read data). It has a function to output the displayed display data externally. Furthermore, all communications between the center and terminals have multiple communication request notification bits, among which a priority communication request bit is assigned to a specific address and a common communication request bit is assigned to terminals at other addresses. Has bits.

By configuring as described above, the following effects can be obtained in the present invention.

(1) Dozens of output points and dozens of input points can be configured in one unit (terminal), and can be configured at low cost.

(2) A communication request bit is included in every communication cycle with the terminal, allowing changes in input signals on the terminal side to be efficiently and quickly transmitted to the center device.

(3) This communication request bit can be specially assigned to a specific terminal whose signal changes frequently.
Using these bits, signals can be transmitted efficiently.

(4) In addition, in a small-scale system with a small number of terminals, communication request bits can be assigned to all terminals, and in a large-scale system with many terminals, a large number of communication request bits can be assigned to a small number of communication request bits. By assigning terminals, you can easily configure the system.

Particularly, according to the present invention, in controlling communication between the center device and the terminal, the terminal stores key read data and subsequent changes in the data, and responds to new key read data or the previous key read data in response to a communication request from the center device. By having a function that sends any of the sent key reading data and requests the center device to continue communicating with its own terminal if there is a change mark in the key reading data in addition to the sent data, the key reading at the terminal is Key read data can always be transmitted to the center device in a short time with high reliability while reducing data storage capacity.

Further, by providing the terminal itself or the center device with a function of restricting the continuation of communication requests with the terminal itself, the continuation of abnormal communication can be prevented, thereby increasing the communication reliability of the entire system.

This invention does not specify the object in particular,
Transmit and display data, output to a distant place,
It can be used for various purposes such as collecting data from a distance.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the configuration of a terminal according to the present invention, FIG. 2 is a diagram showing the timing of communication between the terminal and the center device, and FIG. 3 is a diagram showing the timing of communication between the terminal and the center device. FIG. 4 is a diagram showing the configuration of a system to which the present invention is applied; FIG. 5 is a diagram showing the configuration of RAM in the center device according to the present invention; FIG. 6 is a diagram showing the key input A diagram showing the timing at which a signal (key read data) is transmitted to the center device, and FIG. 7 is a diagram showing a part of the RAM map of the terminal. Code explanation, 1... Center device, 2... Transmission line,
30,300-30n...terminal, 37...display device, 38...key contact, 200,201,202
...Terminal address specification data, 210, 211...
...Terminal response data, 341...Terminal response data section, 220, 221...Display output data, 232
...Terminal input data, 331 ...Display data, 3
42...Key read data, 321...Priority communication request bit, 322...Self terminal communication request bit, 3
23... Common communication request bit, Y1 to Y4... lines
RAM, RU...Unit RAM, Y1a...For communication
RAM data, Y2a... memory data for transmission,
Y3a...Next transmission data (change mark), Y4a
...Next transmission data (change mark).

Claims (1)

[Scope of Claims] 1. As a communication cycle between a center device and a plurality of terminal devices each connected to the center device via a line, the center device specifies the terminal device and the designated designation is performed. A transmission cycle in which an output command is sent to control an output target device connected to a terminal device, and the center device outputs a data transmission command by specifying the terminal device, and an input signal connected to the specified terminal device is transmitted. a reception cycle for transmitting input data from a device from the designated terminal device to the center device; and when the center device determines that there is no need to transmit input data from the terminal device, execute the transmission cycle. In the transmission control method, the center device executes the reception cycle when it determines that it is necessary to send input data from the terminal device, and in the transmission control method, the center device specifies the terminal device in the communication cycle. Next to the signal to be sent, a priority communication request signal that requests the center device to send the input data for each address of the specific terminal device in response to a change in the input data to the specific terminal device to be prioritized; , an own terminal communication request signal in which the designated terminal device itself requests the center device to send the input data in response to a change in the input data from the center device to the designated designated terminal device; In response to the occurrence of a change in the input data to other terminal devices other than the specified terminal device and the specified terminal device, the center device is configured to transmit the input data to the other terminal device, regardless of the address of the other terminal device. a common communication request signal requested from a terminal device, and when the center device detects the priority communication request signal, the center device communicates with the specific terminal device that sent the priority communication request signal in a predetermined order. After the cycle is executed, when the common communication request signal is detected, the communication is performed in the order following the reception cycle of the specific terminal device that sent the priority communication request signal and the designated terminal device that sent the self-terminal communication request signal. sequentially investigating the other terminal devices in a predetermined order to find the other terminal device that sent the common communication request signal;
After executing the reception cycle with this terminal device, when the own terminal communication request signal is detected,
If the designated terminal device that sent this self-terminal communication request signal is the specific terminal device, an address with a higher rank than that of the specific terminal device is assigned, and the specified terminal device that sent the priority communication request signal is In the order following the reception cycle, if the designated terminal device that sent out the own terminal communication request signal is a terminal device other than the specific terminal device, in the reception cycle with the specific terminal device that sent out the priority communication request signal. After executing the receiving cycle with the designated terminal device that sent the self-terminal communication request signal in the next order, returning to the communication cycle in the next order, each of the terminal devices receives the data received from the center device. Alternatively, a first storage area as a transmission/reception buffer that temporarily stores data to be sent to the center device, and a second storage area that stores input data sent from the terminal device to the center device in the previous reception cycle of the terminal device. a storage area; and one or more third storage areas that store change data corresponding to changes in time series of input data after the input data stored in the second storage area.
a storage area, and a data retransmission command for requesting retransmission of the input data transmitted from the terminal device to the center device in the previous reception cycle, the data transmission command from the center device; In this case, the input data stored in the second storage area is transferred to the data sending command from the center device after the data sent from the terminal device to the center device in the previous reception cycle. If the next input data transmission command requests the transmission of input data, the data stored in the second storage area is based on the oldest change data stored in the third storage area. the input data is corrected and newly stored in the second storage area, and the input data newly stored in the second storage area is respectively set in the first storage area and sent to the center device. , each time the input data stored in the second storage area is corrected, the oldest change data stored in the third storage area is replaced with the next oldest change data. transmission control method.