JPH04148260A - Communication system between main body and terminal - Google Patents

Abstract

PURPOSE:To prevent a process efficiency from being decreased caused by the retry increase of a main body processor when congesting a terminal processor by communicating by the initiative of the terminal processor. CONSTITUTION:In a terminal processor 10A, a terminal processing means 12 executes an internal process, and when a request to transfer data from the terminal processor 10A to a main body processor 20 is generated, it is informed to a terminal communication control means 11A that there are transfer data. The terminal communication control means 11A transmits a transfer request to the main body processor 20. In the main body processor 20, a main body processing means 21 executes the internal process, and when a main body communication control means 22 receives the transfer request, the means 22 interrupts the main body processing means 21 and starts a communication process, then returns a reception confirmation to the terminal processor 10A. Thus, it is possible to prevent the process efficiency from being decreased caused by the retry increase of the main body processor 20 when congesting the terminal processor.

Description

[Detailed Description of the Invention] [Summary] A communication control method between a terminal processing device and a main processing device. Processing efficiency is improved due to an increase in number of tries by the main processing device when the terminal processing device takes the lead, by performing communication under the initiative of the terminal processing device. A communication method between a terminal processing device and a main processing device in a system in which a terminal processing device is connected to a main processing device, with the aim of preventing the main processing device from degrading. a terminal communication control means for controlling communication between the two; and a terminal communication control means for executing internal processing within the terminal processing device and activating the terminal communication control means during the internal processing to control communication with the main processing device. The main body processing device includes a terminal processing means for executing internal processing in the main body processing device, and transmits and receives data between the main body processing means for executing internal processing in the main body processing device and the terminal processing device, and transmits data from the terminal processing device. When receiving the data, it interrupts the main body processing means, analyzes the received data, returns the analysis result and data according to the presence or absence of transfer data from the main processing device side to the terminal processing device, and terminates the communication. The main body communication control means is provided to sometimes return the main body processing means to normal processing, and the terminal processing apparatus is configured to take the lead in communication between the terminal processing apparatus and the main body processing apparatus.

[Industrial application field]

The present invention relates to a communication processing method between a terminal processing device and a main processing device.

Generally, a console for man-machine interface is connected to the data processing device (hereinafter referred to as main processing device), but the console can also be a typewriter or a display terminal (VDU) that combines a display unit and keyboard. has been used a lot. However, in recent years, there has been a strong tendency to replace these with personal computers (PCs, hereinafter abbreviated as personal computers).

Due to the above trends, when using a computer with a wealth of functions, it is becoming more and more common to utilize internal software functions to increase functionality and support man-machine interfaces, rather than just functioning as a terminal. It's coming. For example, functions that improve convenience are being added, such as cataloging command input, logging/suppressing messages, and providing command menus.

However, as a result of adding these functions, the computer performs a lot of processing, and when the main processing unit outputs to the computer as a terminal, it cannot output because the terminal is in a processing state, and the main processing unit The processing device often repeats output retries, which has created a problem in that it places a load on the processing of the main processing device and reduces processing efficiency.

In order to reduce the waiting time of the main processing unit when the terminal is processing, the PC operating system (O8
) have multi-task processing capabilities, but in this case, the processing burden on the computer becomes even heavier and the processing becomes more complicated. Another strategy is needed.

[Prior Art] FIG. 7 is a block diagram of the prior art, and FIG. 8 is a communication procedure diagram of the prior art.

Hereinafter, FIGS. 7 and 8 will be explained.

Within the terminal processing device 30, a terminal processing section 32 performs internal processing (including a standby state). When data is transferred from the terminal processing device 30 side to the main processing device 40, a command for data transfer is input from, for example, a keyboard (not shown). This command is executed by the terminal processing section 32.
A control code (
For example, ENQ) is sent to the main processing device 40 (■ in FIG. 8, hereinafter simply referred to as ■). Main body processing device 4
0, the receiving unit 43 of the main body communication control unit 42 receives this control code, and sends back a control code (DC return) through the transmitting unit 44 that confirms the reception and indicates that it is possible to send the next data. (■).

When the receiving unit 35 of the terminal communication control unit 31 receives the control code, the terminal processing device 30 transmits the control code to the transmitting unit 34.
Start transferring data via (■).

When the transfer of all the data is completed, the main processing device 40 returns a control code (DC4) indicating that all the transferred data has been received (■), and completes the data transfer.

Next, the case where a message is transmitted from the main processing device 40 to the terminal processing device 30 will be described.

In the main body processing device 40, the main body processing unit 41 performs normal processing (including standby state), but when a message to be transferred from the main body processing device 40 to the terminal processing device 30 occurs, the main body processing unit 41 A data transfer request is sent to the communication control unit 42, and upon receiving the request, the main body communication control unit 42 sends a control code (E) indicating the transfer request from the transmission unit 44.
NQ) is sent to the terminal processing device 30 (■). The terminal processing device 30 returns a control code (ACK) indicating confirmation of reception via the transmitter 44 of the terminal communication controller 31 (■).

The main processing device 40 thereby starts transferring data via the transmitter 44 (■). When the terminal processing device 30 receives all the data, it should return a control code (ACK) to the main processing device 40 indicating that it has received all the transferred data (■)
, complete the data transfer.

As described above, in the conventional technology, when the main processing device 40 sends a message, a transfer request is issued from the main processing device 40 side, but when the terminal processing device 30 is performing internal processing, the transfer request (the 8) cannot be sent, retries are repeated at regular intervals until the terminal processing device 30 accepts the transfer request. However, the terminal processing device 3
If a high-performance computer is used for 0,
The terminal processing device 30 may not be in an idle state for a long time, and the main processing device 40 has to repeat retries for a long time, resulting in an increase in the load on the main processing device 40 and a decrease in processing efficiency.

[Problem to be solved by the invention]

In conventional communication between terminals, data transfer from the main processing device to the terminal processing device uses a method in which a transfer request is made from the main processing device side, so the processing amount of the terminal processing device is large and the terminal processing device is idle for a long time. If this is not the case, the transfer request is not accepted by the terminal processing device, resulting in a problem in that processing efficiency decreases due to increased processing due to repeated attempts by the main processing device.

An object of the present invention is to prevent a decrease in processing efficiency due to an increase in the main processing device connection attempts on the terminal processing device 30 side by performing communication under the initiative of the terminal processing device.

[Means to solve the problem]

FIG. 1 is an explanatory diagram of the principle of the present invention, and FIG. 2 is a detailed explanatory diagram of the present invention.

In the figure, 10A and 10B are terminal processing devices, 20 is a main processing device, and 11A and 11B are terminal processing devices 10A, respectively.

Terminal communication control means 12 is provided in the terminal communication control means 11B and controls communication with the main body processing device 20;
When a large amount of data is to be transmitted to the main processing device 20, the data is divided into fixed amounts and transmitted, and each time the transmission of all data or the fixed amount of data is finished,
12 is a main body transmission request monitoring means that performs processing for checking the presence or absence of transmission data from the main body processing device 20 side to the terminal processing device 2θ from the terminal processing device 10B to the main body processing device 2θ; , 10B
1. During the internal processing, the terminal communication control means 11A and 11B are activated to control the main processing device 2.
This is a terminal processing means that controls communication with 0.

Further, 2I is a main body processing means provided in the main body processing device 20 to execute internal processing within the main body processing device 20;
22 exchanges data with the terminal processing devices 10A, 10B, interrupts the main body processing means 21 when receiving data from the terminal processing devices 10A, 10B, and analyzes the received data. main body communication control means that returns the results and data depending on the presence or absence of transferred data from the main body processing device 20 side to the terminal processing devices 10A, 10B, and causes the main body processing means 21 to return to normal processing when communication is terminated; It is.

A third aspect of the present invention is a method of using only codes having a difference of 2 bits or more between control codes in a plurality of control codes for controlling communication in communication between the terminal processing device IO and the main processing device 20, The terminal communication control means 11A
, 11B and the main body communication control means 22 (not shown).

[For production]

FIG. 3 is a basic communication procedure diagram of the present invention. Hereinafter, the present invention will be explained in detail using FIG. 1, FIG. 2, and FIG. 3.

In FIG. 1, within the terminal processing device 10A, the terminal processing means 12 is performing internal processing (including a standby state).
When a request to transfer data is issued from the terminal processing device 10A to the main processing device 20, the terminal communication control means 11A
Notify that there is data to be transferred. The terminal communication control means 11A thereby transmits a transfer request to the main processing device 20 (see FIG. 3). Main body processing device 2
0, the main body processing means 21 is performing internal processing, but when the main body communication control means 22 receives the transfer request, it interrupts the main body processing means 21 and starts communication processing, and sends reception confirmation to the terminal processing device 10A. Return it to (■).

As a result, the terminal communication control means 11A transfers the transfer data input via the terminal processing means 12 to the main body processing device 20.
Send to (■). When the transfer of all data is completed, the main body communication control means 22 notifies the terminal processing device 10A that the reception of the transferred data has been completed (■), and also notifies the main body processing means 21 that it is okay to return to normal processing. .

The terminal processing device 10A completes the data transfer by receiving information confirming the completion of the reception from the main body communication control means 22, and the terminal processing means 12 resumes internal processing.

Next, a case will be described in which a message is sent from the main processing device 20 side.

The terminal processing means 12 in the terminal processing device 10A performs internal processing (
(including a standby state), the terminal communication control means IIA is activated (at regular intervals in the case of a standby state) at the time of a break in internal processing. Upon this activation, the terminal communication control means 11A sends information to the main processing device 20 to confirm the presence or absence of a data transfer request from the main processing device 20 side to the terminal processing device 10A (Jl! 3, ■).

When the main body processing device 20 has data that it wants to transfer to the terminal processing device 10A, the main body processing means 21 displays this on the main body communication control means 22 in advance, so the main body communication control means 22 transfers data from the terminal processing device 10A. When receiving the information confirming whether or not the transfer is necessary (■), it returns a transfer request to the terminal communication control means 11A (■). The terminal communication control means 11A sends confirmation that it has received this to the main body communication control means 22, informing it that data transfer may be performed (■).

In response to this, the main body communication control means 22 transmits the data (■). When all the data is received, the terminal communication control means 11A
indicates that the received data is normal.
2), the communication processing of the terminal processing device 10A is completed. When the main body communication control means 22 receives this notification, it notifies the main body processing means 21 that it is OK to return to normal processing, and completes the data transfer processing.

Next, FIG. 2 will be explained. Since the operation in FIG. 2 is almost the same as that in FIG. 1, only the different points will be explained.

In FIG. 1, when data is being transferred from the terminal processing device 10A to the main processing device 20, a message (
data) cannot be sent. Therefore, if the amount of data transferred from the terminal processing device 10A is large, the main processing device 2
This causes a situation in which messages to be sent are stuck on the 0 side.

The terminal processing device 10B in FIG. 2 has a main body request confirmation means 13 in the terminal communication control means 11B to prevent the above-mentioned stack from occurring in the main processing device 20.

Assuming that data is now being transferred from the terminal processing device 10B to the main processing device 20, the state at this time is the same as (2) in FIG. When the data transfer is completed, the main processing unit 20 sends information (
(2) is sent, but when the terminal communication control means 11B receives this, the main body request confirmation means 13 causes the terminal communication control means 11B to send information to the main body processing device 20 to confirm the presence or absence of a transfer request. This information is exactly the same as ① in FIG. 3, and is for inquiring whether there is any data to be transferred from the main processing device 20 side. If the main body processing device 20 does not have the transfer data, the main body communication control means 22 notifies the terminal communication control means 11B that there is no transfer request (not shown in FIG. 3). As a result, the terminal processing device 10B completes the data transfer, but thereafter, the terminal communication control means 11B periodically sends a main body request presence check (■ in FIG. 3) to the main processing device 20 and sends it to the main processing device 20. Prevent data from stacking.

In addition, in the above, when the terminal processing device 10A sends the main processing device 20 the main processing device 20 the main processing device 20, if the main processing device 20 has the transfer data, the main processing device 20 The control means 22 sends a transfer request. This transfer request has the same characteristics as ① in FIG. 3, and the same operations as ① to ② in the same figure are performed thereafter.

The above is the operation when the data transfer from the terminal processing device 10B is completed, but if the amount of data to be transferred is large, the main body transmission request confirmation means 13 divides the data to be transferred and transfers the divided data. Each time the transfer is completed, the terminal communication control means 11B sends information for confirming the presence or absence of a transfer request to the main processing device 20 in the same manner as described above. If there is no data to be transferred, the main body processing device 20 notifies the terminal communication control means 11A of this fact, but this has the same effect as (■) in FIG. The next data is sent out via means 11A.

If the main processing device 20 has transfer data, it performs the same operation as when the data transfer is completed.

As described above, stacking of transmission data in the main processing device 20 is prevented.

Furthermore, in the above-described inter-terminal communication system, any code can be used as the control code exchanged between the terminal communication control means 11A, 11B and the main body communication control means 22; By using only codes that have a difference of 2 or more bits, it is possible to prevent erroneous processing when the bits that make up the control code change by l bits or are shifted by 1 bit. . (Details will be explained in Examples.)
Embodiment] FIG. 4 is a block diagram of an embodiment of the present invention, FIG. 5 is a communication procedure diagram of an embodiment of the present invention, and FIG. 6 is an explanatory diagram of the principle of rate control code adoption of the present invention.

In the figure, the same objects as in FIGS. 1 and 2 are indicated using the same symbols, 14.15 is the transmitting section and the receiving section of the terminal communication control section 11B, respectively, and 23.24.25 is the main body communication control section, respectively. 22 is a receiving section, a transmitting section, and an analyzing section; 26 is a storage section for transfer data of the main processing device 20; Furthermore, since the configuration shown in the diagram explaining the principle of the present invention in FIG. 2 includes all the functions shown in FIG. 1, the configuration shown in FIG. The present invention will be explained in detail with reference to the figures.

First, the operation when there is no data transfer request for both the terminal processing device 10B and the main processing device 20 is shown in FIGS. 4 and 5 (1).
).

In this state, the terminal processing unit 12 in the terminal processing device 10A is in a processing phase performing internal processing, and the main processing unit 21 in the main processing device 20 is performing normal processing (both include standby state). ), but
The terminal processing unit 12 periodically activates the terminal communication control unit 11B during internal processing, and shifts to the communication phase. When the terminal communication control unit 11B is activated, the transmitting unit 14 transmits information for confirming the presence or absence of transfer (the control code is, for example, NUL, all examples of control codes are shown below) to the main processing unit 20 (fifth
Figure ■). The main body processing unit 21 of the main body processing device 20 monitors the receiving unit 23 of the main body communication control unit 22 during normal processing, and when the receiving unit 23 receives the transfer presence confirmation information (■), it detects this. Then, the main processing device 20 enters interrupt processing and shifts from normal processing to communication processing.

When the receiving unit 23 also receives information from the terminal communication control unit 11B, it sends it to the analysis unit 25, but in response to the transfer confirmation information (■), the analysis unit 25 sends the information from the main processing device 20 to the terminal processing device 10B. Check whether there is any data to transfer. The presence or absence of transfer data is sent from the main processing unit 21 to the analysis unit 25 via the transfer data storage unit 26, but at this time there is no transfer data, so the analysis unit 25 sends a message to the transmission unit 24. and to reply that there is no transfer request. In response to this, the transmitting unit 24 sends a response indicating no transfer request (NUL) to the terminal communication control unit 11B (■), and returns to normal processing.

When the terminal communication control section 11B receives this answer (2), it reports it to the terminal processing section 12, and the terminal processing device 10B returns to the processing phase again. Note that the terminal processing section 12 and the terminal communication control section 11
B periodically repeats the above operations.

Next, the case where data is transferred from the terminal processing device 10B will be explained using FIG. 4 and FIG. 5 (2).

When the terminal processing device 10B is in the processing phase, when data to be transferred to the main processing device 20 is generated, the terminal processing device 10B recognizes this, starts the terminal communication control unit 11B, and shifts to the communication phase. The transmitter 14 of the terminal communication controller 11B sends a transfer request (ENQ) to the main processing device 20.
), the main processing device 20 shifts to communication processing by interrupt processing, as described above. Main body communication control section 2
2 is information (A
CK) is returned (■).

Upon receiving this, the terminal processing device 10B proceeds to transmit the transfer data size and notifies, for example, 2 bytes of data that the amount of data to be transferred is n bytes (■). The main body communication control unit 22 confirms reception (ACK) in response to this.
Notify (■). As a result, data transfer is started, and n bytes of data are sent from the terminal communication control section 11B to the main body communication control section 22 (■). Main body processing device 2
0, when receiving the previously notified amount of data, that is, n bytes, sends reception confirmation information (ACK) to notify that all data has been received (■), and the main processing device 20 ends the communication process. The terminal processing device 10B also completes the transfer upon receiving the reception confirmation information (■).

Since the terminal communication control section 11B has a main body request confirmation section 13, the terminal communication control section 11B has a main body request confirmation section 13.
Transfer request presence/absence confirmation information (NUL) is sent to confirm the presence or absence of transfer data.

Does this have exactly the same role as Figure 5 ■?
The main processing device 20 receives this and starts the communication process again, and if there is no transfer data, it responds with no transfer request (0), which is the same as in the above (2). In this case, the communication process is completed with both the terminal processing device 1OB and the main processing device 20, and the process moves to FIG. 3(1). Further, if the main processing device 20 has transfer data, it sends a transfer request (0) and then moves on to executing the request, which will be explained later because it has the same effect as @, which will be described later.

Next, the case where data is transferred from the main processing device 20 will be explained using FIG. 4 and FIG. 5 (3).

When data to be transferred to the main processing device 20 side is generated,
The main body processing unit 21 notifies this to the main body communication control unit 22 via the transfer data storage unit 26, but the terminal processing device 1
0B cannot make a transfer request to the terminal processing device 10B until it periodically checks whether there is a transfer request on the main processing device 20 side (■) in FIG. The receiving section 23 of the section 22 is connected to the terminal processing device 10.
Receive transfer request confirmation (NUL) from B (0,■
) and - The analysis unit 25 causes the transmission unit 24 to send a transfer request (ENQ) (0). Main body processing device 20
The communication is temporarily terminated at this stage, but the same holds true for each of the following stages (see Fig. 5).

Upon receiving the transfer request @, the terminal communication control unit 11B notifies that the transfer request has been received and sends a transfer permission notification (ACK) indicating that data transfer is possible (0). The main processing device 20 notifies the amount of data (n bytes) to be transferred via the analysis unit 25 using, for example, 2 bytes of data (@).
, notification of normal reception data from the terminal processing device 10B (A
CK), data is transferred (0). The main processing device 20 does not notify the end of the data transfer, but when the terminal processing device 10B receives all the data amount previously notified, that is, n bytes of data, the terminal processing device 10B notifies the terminal processing device 10B that the received data is normal. Sends information (o) and ends data transfer. The main processing device 20 that has received this information 0 completes the data transfer, and the main processing device 20
Information (NUL) indicating that there is no data to be transferred subsequently is sent from the 0 side, and the data transfer is completed. As a result, the terminal processing device 10B moves to the processing phase,
The main processing device 20 also shifts from the communication processing state to the normal processing state.

Next, the principle of adoption or rejection of control codes will be explained with reference to FIG.

A control code is used depending on the system, but
In the present invention, contrary to the prior art, since the terminal processing device side takes the lead in communication, it is desirable to simplify communication control including error handling. As a method for this purpose, it is effective to employ a control code that can be confirmed to be an error even if the error is not corrected when an error occurs in the control code.

FIG. 6 shows an example of the embodiment.

FIG. 6 shows a control code "05" as an example, assuming that communication between terminal bodies is performed in units of 8 bits and the last 5 bits are used for the control code. Note that when displaying in two hexadecimal digits, the 10th digit is indicated by whether the 4th bit is 0 or 1, ignoring the most significant 3 bits.

When code “05” is used as a control code, its bit configuration is shown at the top of Figure 6, and one bit of “l” among the five target bits is “0”. The same figure shows a case where a change (decrease by 1 bit), a case where 1 bit in "0" changes to "l" (increase by 1 bit), and a case where a shift by 1 bit is made. These bit configurations are expressed in hexadecimal numbers from “Ol” to “OB” shown in the same figure.
However, if you use "05" as a control code and do not use the above eight codes as a control code, if these codes are detected, it will be determined that they are not regular control codes. can be identified.

The above principle means that codes with a difference of 1 bit are not adopted as control codes, and therefore, only control codes with a difference of 2 bits or more are to be adopted. Assuming the bit configuration as shown in Figure 6, the control code that conforms to the above principle is “00” (N
UL), "05", "06", "09"IB", etc. can be selected, but it is quite possible to perform the communication procedure as shown in FIG. 5 using only these selected control codes.

As described above, in the configuration of FIG. 4, the terminal processing device 1
Even if 0B is performing internal processing for a long time, the main processing device 20 periodically checks whether there is a transfer request to the main processing device 20 during the internal processing.
Transfer data is not stacked without being accessed.

Note that the embodiments shown in FIGS. 4 to 6 merely show one embodiment of the present invention, and the effects of the present invention can be obtained even if the details of the communication procedure are different from those in FIG. 5, for example. It is clear that there is, and it is also clear that the structure and type of the control code are not limited to those shown in FIGS. 5 and 6.

〔Effect of the invention〕

As explained above, according to the present invention, communication between the terminal processing device and the main processing device in a system in which the terminal processing device is connected to the main processing device is performed under the initiative of the terminal processing device, so that the terminal processing device It is possible to prevent a decrease in processing efficiency due to an increase in main processing unit retries during busy periods, and even when the terminal processing unit performs long internal processing or data transfer, it is possible to prevent Since the system periodically checks whether there is a transfer request to the main processing device, it is possible to prevent the transfer data from stacking up due to the main processing device not being able to access the terminal processing device, and to ensure smooth communication between the terminal main bodies. It can be carried out.

In addition, by using only codes that have a difference of 2 bits or more between control codes for the plurality of control codes that control communication, it is possible to avoid errors when the bits that make up the control codes change or shift by 1 bit. This makes it possible to easily prevent processing from being performed, which greatly contributes to improving processing efficiency and reliability in communication between the terminal processing device and the main processing device.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is a detailed explanatory diagram of the present invention, Fig. 3 is a basic communication procedure diagram of the present invention, Fig. 4 is a configuration diagram of an embodiment of the present invention, Fig. 5 6 is a diagram illustrating an embodiment of the communication procedure of the present invention, FIG. 6 is an explanatory diagram of an embodiment of the principle of adoption or rejection of control codes of the present invention, FIG. 7 is a configuration diagram of the prior art, and FIG. 8 is a diagram of the communication procedure of the prior art. In the figure, terminal processing devices 11A, 11B, 11B, 10A, 10B, ...
−・−・Terminal communication control means 12・−・−・−・・−・・
・−・−・・・・=−・Terminal processing means 13・−・−・・
−・・−−−−−−・・Main body request confirmation means 20
・・−・・−・−−−−−・・−・・−・
・-Main processing device 21・-・・・−・・・・・・・
・-・・・・・Body processing means 22 ・−・・・・
・・−・−・・−・・−・・− Body communication control means. Diagram for explaining the principles of the present invention (1) Diagram for explaining the principles of the present invention (2) Diagram for transmitting commands from the vertically placed side of the terminal processing device main body processing device Sending messages from the main body processing device side Basics of the present invention Communication procedure diagram (Part 1) Terminal body (2) When transferring data from the terminal side Communication procedure diagram (Part 1) Terminal body (3) When transferring data from the main body side Figure (Part 2)

Claims (1)

[Scope of Claims] 1. A communication method between a terminal processing device and a main processing device in a system in which a terminal processing device is connected to a main processing device, wherein the terminal processing device (10A) includes: the main processing device; (20), a terminal communication control means (11A) that controls communication with the terminal processing device (11A);
0A), and during the internal processing, the terminal communication control means (11A) is activated and the main body processing device (11A) is activated.
terminal processing means (12) for controlling communication with
), in the main processing device (20), transmitting and receiving data between main processing means (21) that executes internal processing in the main processing device (20) and the terminal processing device (10A). death,
When data is received from the terminal processing device (10A), the main body processing means (21) is interrupted, the received data is analyzed, and the analysis result and the main body processing device (20
main body communication control means (22) for returning data to the terminal processing device (10A) according to the presence or absence of data transferred from the ) side and for returning the main body processing means (21) to normal processing when communication is terminated; A communication method between terminal bodies, characterized in that the terminal processing apparatus takes the lead in communication between the terminal processing apparatus and the main body processing apparatus. 2. In the terminal processing device (10B), a terminal communication control means (11B) for controlling communication with the main body processing device (20) is provided, and in the terminal communication control means (11B), the above-mentioned When a large amount of data is to be sent from the terminal processing device (10B) to the main processing device (20), the data is divided into fixed amounts and sent, and each time the transmission of all data or the fixed amount of data is finished. , from the terminal processing device (10B) to the main processing device (20).
) side to the terminal processing device (10B).
13), and prevents data transmission requests from stacking on the main processing device (20) side. 3. In communication between the terminal processing device (10A, 10B) and the main processing device (20), only codes having a difference of 2 bits or more between control codes are used for a plurality of control codes for controlling communication; 3. The inter-terminal communication system according to claim 1, wherein erroneous processing is prevented when the bits constituting the control code change by 1 bit or are shifted by 1 bit.