JPH08116331A - Data transmission control method - Google Patents

Abstract

PURPOSE: To provide transmission control method capable of confirming a receiving state in each terminal periodically before all packets are completed to transmit when the same data is transmitted simultaneously from a master device to each terminal equipment for every packet and sufficient only by the irreducibly minimum number of times of transmission without requiring the re-transmission of all packets when it is performed. CONSTITUTION: The master device 1 designates the terminal equipment 2 one by one and requests an ACK/NACK response when performing simultaneous multi-address communication which transmits the same data simultaneously for every packet sequentially. Designated terminal equipment 2 issues the ACK/ NACK response corresponding to the receiving state, however, transmits an abnormal packet No. representing a reception defect when the NACK response is issued. The master device 1 performs the simultaneous multi-address communication of the next packet when receiving the ACK response, and performs the re-transmission of the data starting from the packet representing the reception defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a POS for performing data communication between a master device and a plurality of terminal devices.
The present invention relates to a data transmission control method for simultaneously transmitting the same data from a master device to all terminal devices in a data communication system such as a (point of sales) system.

[0002]

2. Description of the Related Art Generally, in a POS system, a master device and a plurality of terminal devices are network-connected, and a master device and a plurality of terminal devices are connected between a master device and a plurality of terminal devices according to a contention method or a polling / selecting method. I am trying to do data communication with. Further, in the past, in order to improve the transmission efficiency, the data communication method in which the same data is simultaneously transmitted from the master device to each terminal device (hereinafter,
Called a simultaneous broadcast communication method) is known. FIG. 9 is a diagram for explaining this type of broadcast communication system, in which the master device M sequentially transmits the same data to each of the terminal devices T1, T2, and T3 one packet at a time, and finally, While sequentially designating each of the terminal devices T1, T2, T3, a response request for confirming the reception state is transmitted. Here, when each of the terminal devices T1, T2, T3 can normally receive all the packets, it sends an ACK (acknowledgement) to the master device M and cannot receive even one packet normally. If it does, NACK (negative acknowledgment) is transmitted to the master device M. At this time, when the master device M receives the NACK response, from the beginning all packets are retransmitted to the terminal devices T1, T2, T3 by simultaneous broadcast.

[0003]

However, the master device M cannot confirm the reception status at each terminal device T1, T2, T3 until after transmitting all the packets, and at the time of retransmission, Since all packets are retransmitted from the beginning, it takes time to transfer data,
There has been a demand for improved transmission efficiency. The subject of this invention is
When the same data is sent from the master device to each terminal device at the same time, one packet at a time, the reception status at each terminal can be checked periodically before sending all packets, and it is not necessary to resend all packets. age,
It is to be able to realize sufficient transmission control with only the minimum required transmission.

[0004]

Means for Solving the Problem and Its Action The means and action of the first invention (the invention of claim 1) are as follows. In a data communication system for performing data communication between a master device and a plurality of terminal devices, when the master device simultaneously broadcasts the same data sequentially for each packet to each terminal device, Designate each terminal device according to the decided order and set the transmission control information in the packet to request the positive response or negative response that indicates whether the packet was successfully received to the designated terminal device and send it. However, each terminal device sequentially receives the packets transmitted from the master device, and checks whether or not the transmission control information for designating itself is included in the received packet. When specifying, whether the terminal device could normally receive the packet sent this time. If a packet can be received normally, an affirmative response is sent to the master device. When a negative response is sent to the master device together with identification information for identification, and the master device sends an affirmative response from the terminal device, it broadcasts the next packet to each terminal device, and a negative response is sent. When the packet is transmitted, a packet in which reception is poor is detected based on the identification information transmitted together with this negative response, and data is retransmitted from this poor reception packet to each terminal device. By repeating this, the master device sequentially transmits all packets to each terminal device while checking for reception errors at each terminal device.
Means of the second invention (an invention according to claim (2)) and its operation are as follows. In a data communication system for performing data communication between a master device and a plurality of terminal devices, when the master device simultaneously broadcasts the same data sequentially for each packet to each terminal device, The transmission control information that specifies each terminal device according to the determined order and requests a negative response indicating that the packet cannot be normally received to the specified terminal device is set in the packet and transmitted. The terminal device sequentially receives the packets transmitted from the master device, checks whether or not the transmission control information for designating itself is included in the received packet, and the transmission control information designates itself. In this case, the terminal device determines whether or not the packet transmitted this time has been normally received, If the packet is not received normally, the master device sends a negative response to the master device together with the identification information that identifies the packets that have been normally received and the packets that have failed to be received, and the master device sends a negative response from the terminal device. Is sent within a fixed time, and if a negative response is not sent within a fixed time, the next packet is broadcast to each terminal device and a negative response is sent. When the packet is transmitted, a packet in which reception is poor is detected based on the identification information transmitted together with this negative response, and data is retransmitted from this poor reception packet to each terminal device. By repeating this, the master device sequentially transmits all packets to each terminal device while checking for reception errors at each terminal device. Therefore, when the same data is sequentially transmitted from the master device to each terminal device at the same time for each packet,
It is possible to check the reception status at each terminal on a regular basis before the end of transmission of all packets, and it is not necessary to retransmit all packets at the time of retransmission, and it is possible to realize transmission control that requires only the minimum required transmission.

[0005]

[First Embodiment] A first embodiment will be described below with reference to FIGS. FIG. 1 is a diagram for explaining the broadcast communication method performed in the POS system according to this embodiment. In this POS system, a master device 1 (# 1) and a plurality of terminal devices 2 (# 2, # 3, # 4) share the same communication path 3
The master device 1 simultaneously transmits the same data to each terminal device 2 one packet at a time and broadcasts simultaneously. Here, in this embodiment, the packets (1) to (6) are sequentially transmitted, but at this time, the master device 1 has a predetermined order (# 2, # 3, # 4, # 2, # 3). ......), each terminal device 2 is designated one by one, and an affirmative response (ACK) or negative response (NA) indicating whether or not the designated terminal device has successfully received the packet.
CK) is set in the packet and the transmission control information is transmitted.

Each terminal device 2 sequentially receives the packets transmitted from the master device 1 and checks whether or not the transmission control information designating itself is included in the received packet. Here, when the transmission control information designates itself, the terminal device 2 transmits an affirmative response (ACK) to the master device 1 when it can normally receive the packet transmitted this time, If the packet cannot be received normally, a negative response (NAC) is sent to the master device 1 together with the identification information for identifying the packet that has been normally received and the packet that has not been received.
K) is transmitted. Here, the identification information is for identifying the reception state, and in the present embodiment is a packet number for indicating an abnormal packet that has become a reception error, and is transmitted to the master device 1 together with NACK.

When the ACK response is transmitted from the designated terminal device 2, the master device 1 broadcasts the next packet to each terminal device 2, but when the NACK response is transmitted, this master packet is transmitted. An abnormal packet with poor reception is detected based on the abnormal packet No (reception state identification information) transmitted together with the NACK response, and data is retransmitted from each abnormal packet to each terminal device 2. In this way, the master device 1 sequentially transmits all packets to each terminal device 2 while checking the reception error at each terminal device 2.

The concrete example shown in FIG. 1 is packet (1).
When broadcasting (6) to (6) packet by packet, the master device 1 sends each terminal device 2 to # 2, # 3, # 4, # 2,
It indicates that they are cyclically specified one by one according to the order of # 3 .... Further, when the packet (1) is transmitted by designating the terminal # 2, there is an ACK response from the terminal # 2.
Packet (2) is transmitted by designating the following, and thereafter, every time packet (2), (3), (4), (5) is transmitted, ACK is sent from the designated terminals # 3, # 4, # 2, and # 3. It shows when there is a response. Then, when the packet (6) is transmitted by designating the terminal # 4, there is a NACK response from the terminal # 4, and the next terminal # 2 is conditioned on this condition.
Is specified to indicate that an abnormal packet is retransmitted.

FIG. 2 is a block diagram showing the basic configuration of the master device 1 or the terminal device 2. Reference numerals 11 to 18 indicate constituent elements of the master device 1, and reference numerals 21 to 28 in parentheses indicate constituent elements of the terminal device 2. Hereinafter, only the configuration of the master device 1 will be described, and the description of the terminal device 2 will be omitted. CPU11
Is for controlling the overall operation of the master device 1 according to various programs in the ROM 12.
The data input from 3 is displayed and output from the display unit 14 and stored in the RAM 15. Further, the CPU 11 prints out the contents of the RAM 15 from the printer 16 in response to the print command from the keyboard 13, and writes the contents of the RAM 15 into the communication buffer 17 in response to the communication command from the keyboard 13, and through the communication interface 18. Then, the data from the terminal device 2 is fetched via the communication interface 18 and the communication buffer 17 and set in the RAM 15.

FIG. 3 shows a master device 1 and a terminal device 2.
The data format of the packet transmitted / received between and is shown. First, the "destination" at the head is the destination terminal number at the time of packet transmission, and when the content is "00", it indicates that all terminals are targeted for simultaneous broadcast communication. Next, "content" indicates the type of packet, which is "00" for a normal data packet, "01" for an ACK packet, and "02" for a NACK packet. The "source" indicates the source number of the packet transmitting side. “ACK / NACK request terminal No” indicates a terminal No that requests an ACK / NACK response by simultaneous broadcast. “Packet No” is a packet number to be transmitted, and is normally incremented by “1” from “0001”.

Next, the operation of this embodiment will be described with reference to the flow charts shown in FIGS. Now, when transmitting data from the master device 1 to each terminal device 2 by simultaneous broadcast, the master device 1 operates according to the flowchart shown in FIG. 4, and each terminal device 2 operates according to the flowchart shown in FIG. First, since the master device 1 sequentially transmits the same data to each terminal device 2 in a simultaneous broadcast to each terminal device 2, packet number "00" indicating that it is the first packet in the PN register is sent.
01 "and set each terminal device 2 one by one according to a predetermined order.
"1" indicating that the first terminal device (# 2) is the designated terminal is set in the ART register (step A1).

After performing such initialization processing, the master device 1 checks whether or not all the data to be transmitted has been transmitted (step A2), but it is at the start of transmission, and the presence of data is detected in step A2. Then, the process proceeds to step A3, the set data is read from the PN register and the ART register, and transmission data is created as a normal data packet. In this case, the "destination" of this packet is "00" indicating that it is a simultaneous broadcast targeting all terminals, and the "content" is "00" indicating that it is a normal data packet. When the transmission data for one packet is created in this way, the master device 1 transmits this to all the terminal devices 2 by simultaneous broadcast (step A4).

After that, the master device 1 waits for reception until an ACK / NACK response is received from the designated terminal device, and when an ACK / NACK packet is received (step A5), based on the "contents" set in the received packet. It is checked whether the lever packet is an ACK packet (step A6). Now, if it is an ACK packet, the packet is normally received by the terminal device 2 side, so the process proceeds to step A12, where "1" is added to the value of the PN register to transmit the next packet.
Update No. Also, in order to specify the next terminal device (# 3), "1" is added to the value of the ART register and A
The CK / NACK request terminal number is updated (step A10). Then, an ET that stores the value of the ART register and the number of terminals connected (three in this embodiment)
It is compared with the value of the C register to check whether ART> ETC, that is, whether all the terminal devices have been designated once (step A11). Where ART> ET
If it is C, the initial value "1" is set to the value of the ART register (step A13), but the value of the ART register is now "2", and therefore the process returns to step A2, and the transmission data for the next one packet is transferred. It is created and broadcast to all terminal devices 2 (steps A3 and A4). Then, the ACK / NACK packet transmitted from the designated terminal device 2 is received (step A5), and the response content is AC.
If it is a K packet, the above operation is repeated until all the packets are transmitted.

The operation of each terminal device 2 at the time of simultaneous broadcast communication will be described with reference to the flowchart shown in FIG. First, each terminal device 2 is in a waiting state for receiving a simultaneous broadcast from the master device 1 (step B1), and upon receiving the simultaneous broadcast, refer to the ACK / NACK request terminal No. included in the packet. Then, it is checked whether the self is designated (step B2). Here, if it designates itself, whether or not the designated terminal device 2 has normally received all the packets received up to that time, that is, from the last designation of the terminal device to the present designation. In addition, when the packet transmitted from the master device 1 cannot be normally received, the terminal device 2 stores and holds the packet number of the reception failure as the abnormal packet number,
The reception state up to that point is confirmed based on whether or not the abnormal packet No is stored (step B3).

Now, the ACK / NACK requesting terminal No. included in the received packet this time does not specify its own terminal device 2, or even the terminal device 2 specifying itself stores an abnormal packet No. However, the terminal device 2 that has not normally received the received packets up to that point operates as follows. First, a parity check or the like is used to check whether or not the packet transmitted this time has been normally received (step B6).
If the packet is normally received, the data in the packet is taken in and data setting is performed according to the type of the data (step B7). Then, A in the packet
In the terminal device 2 in which the CK / NACK request terminal No specifies itself (step B8), an ACK packet is created and transmitted to the master device 1 (step B).
9).

On the other hand, when the current packet cannot be received normally, the terminal device 2 whose ACK / NACK request terminal No specifies itself (step B10) sets the current packet No in the NACK packet. And send it to the master device 1 (step B
11), the other terminal devices 2 use this packet No.
Is stored and stored as the abnormal packet number (step B
12). That is, the terminal device 2 immediately creates a NACK packet and transmits it to the master device 1, but the other terminal devices 2 store and hold the packet number of this time, which is the reception failure, until the next self device is designated. After that, each terminal device 2 waits for the simultaneous broadcast (step B1).

In this waiting state, when the next packet is transmitted and the packet designates itself, if the abnormal packet No is stored and held in the terminal device 2 (steps B2 and B3), the abnormal packet is stored. No for N
It is set in the ACK packet and transmitted to the master device 1 (step B4). Then, the abnormal packet No. stored and held in the terminal device 2 is cleared (step B5), and the reception of the simultaneous broadcast is awaited again (step B1). In this way, each terminal device 2 repeats the above-mentioned operation every time it receives the simultaneous broadcast. By this, AC
In response to the K / NACK request, the terminal device 2 creates an ACK packet or a NACK packet in response to the request and sends it to the master device 1.

On the other hand, the master device 1 is the terminal device 2
When a NACK packet is transmitted from the NACK packet, it is detected in step A6 of FIG. 4 and the process proceeds to step A7.
o) is fetched and set in the EPN register. Then, from the value of the PN register (this transmission packet No.), E
The value of the PN register (abnormal packet No.) is subtracted, and the transmission data is returned by the packet corresponding to that value (step A8). For example, if the packet number this time is "0010",
If the abnormal packet number is “0007”, the transmission data for 3 packets is returned. Then, the value of the EPN register is set in the PN register (step A9). In this case, in the above example, the values in the PN register are "0010" to "00".
07 ". Hereinafter, a process of updating the value of the ART register and designating the next terminal device 2 (step A1)
0, A12, A13), and then the process returns to step A2. Therefore, when the NACK packet is transmitted, the master device 1 retransmits the data from the abnormal packet which has become the reception failure. Note that the terminal device 2 side normally receives the packet retransmitted from the master device 1, thereby compensating for the portion that could not be normally received before that time, and the missing of the received data is eliminated.

As described above, in the present embodiment, when the same data is sequentially transmitted from the master device 1 to each terminal device 2 in a broadcast manner for each packet, each terminal device is transmitted before all packets are transmitted. By designating 2 in a predetermined order, the receiving state of the designated terminal device 2 can be confirmed based on the ACK packet or the NACK packet transmitted from the designated terminal device 2, and at the time of retransmission, all packets can be confirmed. Since it is possible to retransmit from an abnormal packet that has become poorly received instead of retransmitting, it is possible to efficiently perform data transmission by simultaneous broadcast.

[0020]

[Second Embodiment] A second embodiment will be described below with reference to FIGS. In the first embodiment, the master device 1 requests an ACK response / NACK response from the designated terminal device 2, and the terminal device 2 sends an ACK packet / NACK packet to the master device 1 in response to the request, The device 1 broadcasts the next packet to each terminal device 2 on condition that the ACK packet has been sent. In this second embodiment, the terminal device 2 sends only the NACK packet. When the NACK packet is not transmitted within a fixed time, the master device 1 considers that the terminal device 2 has normally received the packet, and broadcasts the next packet to each terminal device 2 simultaneously. Is.

Here, FIG. 6 is a diagram for explaining the simultaneous broadcast communication method performed in the POS system according to the second embodiment, in which the master device 1 operates according to the flowchart shown in FIG. Operates according to the flowchart shown in FIG. This FIG. 7 is substantially the same as the flowchart (FIG. 4) for explaining the operation of the master device 1 in the first embodiment, only step C6 of FIG. 7 is different from step A6 of FIG. Steps C1 to C5 and steps C7 to C13 correspond to steps A1 to A5 and steps A7 to A13 in FIG. Further, FIG. 8 is substantially the same as the flowchart (FIG. 5) for explaining the operation of the terminal device 2 in the first embodiment, and the steps B8 and B9 shown in FIG. 5 do not exist in FIG. ACK / shown in steps B2 and B10 of
The only difference is that the NACK request terminal No. in FIG. 8 is the NACK request terminal No. Steps D1 to D7 of FIG. 8 correspond to steps B1 to B7 of FIG. 5, and step D8 of FIG. D10 corresponds to steps B10 to B12 in FIG. Therefore, details of FIGS. 7 and 8 will not be described below to avoid duplication of description.
Only an overview of the overall operation shall be explained.

That is, when the master device 1 simultaneously broadcasts the same data to each terminal device 2 one packet at a time, the master device 1 sequentially sends each terminal device 2 one by one according to a predetermined order. A request terminal No that requests the NACK response to the specified terminal device 2 is set in the packet and transmitted (steps C1 to C4).

Each terminal device 2 sequentially receives the packets transmitted from the master device 1 (step B1), and checks whether the received packet includes a requesting terminal number for designating itself (step B1).
2) When designating itself, the terminal device 2 sets an abnormal packet No of poor reception in the NACK packet and transmits it to the master device 1 (steps D4, D).
9). If the packet is normally received, the data is set (step D7), but the ACK packet is not transmitted.

The master device 1 checks whether or not the NACK packet has been transmitted from the terminal device 2 within a fixed time (step C6). If the NACK packet has not been transmitted within the fixed time, Packet No
Is designated (step C12), and the next packet is simultaneously broadcast to each terminal device 2 (steps C3, C).
4). On the other hand, when the NACK packet is transmitted before the elapse of a certain period of time, the packet having the poor reception is detected based on the abnormal packet No. in the NACK packet,
Data is retransmitted from each reception failure packet to each terminal device 2 (steps C7, C8, C9, C3, C).
4).

By repeating the above operation, the master device 1 can sequentially transmit all the packets to each terminal device 2 while checking the reception error at each terminal device 2, so Besides having the same effect, the transmission and reception of the ACK packet becomes unnecessary.

In each of the above embodiments, when the NACK packet is transmitted from the terminal device 2 to the master device 1,
Although the abnormal packet No that has become poorly received is transmitted, the last packet No that was normally received before that may be transmitted. In this case, CPU1 is NACK
Broadcasting may be performed from the packet next to the packet No. included in the packet.

[0027]

According to the present invention, when the same data is sequentially transmitted from the master device to each terminal device at the same time for each packet, the reception state at each terminal is periodically confirmed before all the packets are completely transmitted. At the same time, it is not necessary to retransmit all packets at the time of retransmission, and it is possible to realize the transmission control that requires only the minimum required transmission, so that data transmission can be performed efficiently.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a broadcast communication system in a POS system according to a first embodiment.

FIG. 2 is a block diagram showing a basic configuration of a master device 1 or a terminal device 2.

FIG. 3 is a diagram showing a data fort of a packet transmitted and received between the master device 1 and the terminal device 2.

FIG. 4 is a flowchart showing an operation of the master device 1 at the time of simultaneous broadcast communication.

FIG. 5 is a flowchart showing the operation of the terminal device 2 during simultaneous broadcast communication.

FIG. 6 is a diagram for explaining a broadcast communication method performed by the POS system according to the second embodiment.

FIG. 7 is a flowchart showing the operation of the master device 1 at the time of simultaneous broadcast communication in the second embodiment.

FIG. 8 is a flowchart showing the operation of the terminal device 2 during a simultaneous broadcast communication in the second embodiment.

FIG. 9 is a diagram for explaining a conventional broadcast communication system.

[Explanation of symbols]

 1 Master Device 2 Terminal Device 11 CPU 12 ROM 13 Keyboard 15 RAM 17 Communication Buffer 18 Communication Interface

Claims (2)

[Claims] 1. A data communication system for performing data communication between a master device and a plurality of terminal devices, wherein the master device simultaneously transmits the same data to each terminal device in sequence for each packet. When carrying out, the transmission control information for designating each terminal device according to a predetermined order and requesting an affirmative response or a negative response indicating whether or not the packet can be normally received to the designated terminal device is included in the packet. , And each terminal device sequentially receives the packets transmitted from the master device, and checks whether or not the transmission control information for designating itself is included in the received packet, When the transmission control information designates itself, the terminal device normally handles the packet transmitted this time. It is determined whether or not the packet can be received, and if the packet can be received normally, an acknowledgment is sent to the master device. If a positive response is sent from the terminal device, the master device sends a negative response to the master device together with the identification information for identifying the packet that has become a packet. If a negative response is sent,
Based on the identification information transmitted together with this negative response, a packet with poor reception is detected, data is retransmitted from this poor reception packet to each terminal device, and the master device repeats the operation. A data transmission control method, wherein all packets are sequentially transmitted to each terminal device while checking a reception error in the device. 2. A data communication system for performing data communication between a master device and a plurality of terminal devices, wherein the master device simultaneously sends the same data to each terminal device in sequence for each packet. When performing, set each terminal device according to a predetermined order, and set transmission control information in the packet requesting a negative response indicating that the packet could not be normally received to the specified terminal device. Each terminal device sequentially receives the packets transmitted from the master device, and checks whether or not the transmission control information for designating itself is included in the received packet. If the terminal device specified itself, could the terminal device normally receive the packet sent this time? If the packet cannot be received normally, a negative response is sent to the master device together with the identification information for identifying the packet that has been normally received and the packet that has failed to be received. Check whether the negative response is sent from the terminal device within the fixed time, and if the negative response is not sent within the fixed time, broadcast the next packet to each terminal device simultaneously. However, if a negative response is sent, a packet with poor reception is detected based on the identification information transmitted with this negative response, and data is sent to each terminal device from this poor reception packet. By repeating the re-sending operation, the master device sequentially transmits all packets to each terminal device while checking for reception errors at each terminal device. A data transmission control method characterized in that the data is transmitted.