JP2002051064A - Transmission controller and transmission control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of collision by relieving the load of devices. SOLUTION: The transmission controller is characteristically provided with a reception means that receives a data transmission telegraphic message from a two-wire transmission communication path that makes data transmission with an asynchronous start-stop system, a count means that counts times absence of a received signal from the reception means, a transmission means that transmits the data transmission telegraphic message after the lapse of a prescribed time of the count by the count means, a collision detection bit instruction means that gives an instruction of transmission of bid data with lower priority on the transmission communication line as a collision detection bit next to a start bit, and a 1-bit collision detection means that discriminates the occurrence of collision when receiving data different from transmission data of its own station on the basis of the collision detection bit from the reception means and gives an instruction of transmission stop to the transmission means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to an apparatus for controlling transmission of the MA / CD system.

[0002]

2. Description of the Related Art Conventionally, when data is exchanged between two devices through a two-wire transmission communication path, a control method by polling in which one device is a master and the other device is a slave is employed. Was common. In this case, the master transmits a message to the slave and requests a response from the slave by completely discriminating between transmitting and receiving. At this time, the master is transmitting and the slave is receiving. Next, the slave transmits a message such as a state to the master. At this time, the slave is transmitting and the master is receiving. Since the transmission and reception are completely distinguished in this way, the communication algorithm becomes easy.

In addition, there is a CSMA / CD system in communication on the transmission communication path 3 between the devices 1 and 2. Hereinafter, description will be made with reference to FIG. In the communication operation of each of the series of devices 1 and 2, the reception functions 4 and 5 determine that there is no received message. Accordingly, the transmission functions 6 and 7 transmit the message.
The collision detection functions 8 and 9 always receive during the transmission operation and determine that data different from the data transmitted by the own station has been received, and immediately instruct the transmission operation to stop and switch to the reception operation.
When transmitting data “0” and data “1”, the transmission communication path 3
The upper part has a hardware configuration that gives priority to data “0”. Thereafter, the timing functions 10 and 11 determine that there is no certain received message, and again instruct the transmission of the message that could not be transmitted due to the previous collision. By performing the communication operation as described above by each of the devices 1 and 2, data can be exchanged without crushing each other's data.

[0004]

However, in the above configuration, in the case of the above-mentioned master-slave system, transmission and reception operate completely in distinction, so that the communication algorithm is easy, but the response time is shortened. In this case, it is necessary to shorten the polling interval from the master to the slave and to increase the transmission speed. Also, the master device can transmit to the slave side at the timing of its own station, but the slave side must always keep it waiting for reception, and this time from the slave to the master within a certain time for polling Must be sent to
This increases the load on the device.

In the case of the CSMA / CD system, since there is no relationship between the master and the slave, each device can transmit at a timing convenient for its own station, and the response time can be secured without increasing the transmission speed. During the transmitting operation, the receiving operation is always performed, and the data transmitted by the own station is compared with the data on the transmission channel. If the data is different, it is necessary to immediately switch from the transmitting operation to the receiving operation. This complicates the communication algorithm and increases the load on the device.

[0006]

SUMMARY OF THE INVENTION A transmission control device according to the present invention comprises: a receiving means for receiving a data transmission message from a two-wire transmission communication path for performing data transmission in an asynchronous start-stop synchronization system; A timer for counting the time when there is no signal; a transmitter for transmitting a data transmission message after the count of the timer has elapsed for a predetermined time; and a start bit as a collision detection bit using bit data having a low priority on the transmission communication path. And a collision detection bit instructing means for giving an instruction to transmit next to the transmission means, and giving an instruction to stop the transmission by judging a collision when receiving data different from the transmission data of the own station in the collision detection bit from the receiving means. A 1-bit collision detecting means is provided.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a transmission control device according to one embodiment of the present invention. It is constituted by a two-wire transmission communication path 14 for performing data transmission between the device 12 and the device 13 in a one-to-one asynchronous start-stop synchronization system.

[0008] The device 13 is a receiving means 15 for receiving a data transmission message on the transmission communication path 14 transmitted from the device 12.
A time counting means 16 for counting the time during which no reception signal is received by the receiving means 15; a transmitting means 17 for transmitting a data transmission message after a lapse of a predetermined time from the time counting means 16; Collision detection bit instructing means 18 for giving an instruction to transmit bit data as a collision detection bit after the start bit.

The device A12 includes a receiving unit 19 for receiving a data transmission message on the transmission communication path 14 transmitted from the device B13, a time counting unit 20 for counting the time when there is no received signal by the receiving unit 19, and a time counting unit 20. A transmission means 21 for transmitting a data transmission message after a lapse of a predetermined time from the communication means, and a collision detection bit instructing means for giving an instruction to transmit bit data having a low priority on the transmission channel 14 as a collision detection bit next to the start bit 22; and a 1-bit collision detecting unit 23 that gives an instruction to the transmitting unit 21 to determine a collision when receiving data different from the transmission data of the own station in the collision detecting bit from the receiving unit 19 and to stop the transmission. I have.

The specific operation of the transmission control device configured as described above will be described below with reference to FIG. Since the data transmission control procedure of the CSMA system is the same as that described in the conventional example, here, the level of the priority of the collision detection bit and the bit transmission of the bit having the low priority of the collision detection bit are performed by the device transmitting the CSMA / CBS using one bit. CD
Will be described. Only one bit following the start bit in the data transmission message from device B13 to device A12
Is defined as data "0" (priority in the transmission communication path 14 is high), and data "1" is transmitted from the apparatus A12 to the apparatus B13 (priority in the transmission communication path 14 is low). At this time, the transmission communication path 14 has a hardware configuration that prioritizes data “0”. In this state, low priority data "
When a collision is detected only on the side of the device A12 that transmits "1" as the collision detection bit, the transmission is stopped (the transmission stop arrow in FIG. 2). Here, the data "0" is the data "
Although the priority is higher on the transmission communication path 14 than “1”, this may be reversed.

[0011]

As described above, the present invention provides a device B having a receiving means, a timing means, a transmitting means and a collision detection bit designating means, a receiving means, a timing means, a transmission means, a collision detection bit designating means and a 1 bit By having the device A having the collision detection means and the transmission channel, only the device transmitting the lower priority bit on the transmission channel has a 1-bit CS.
By performing MA / CD, data can be exchanged smoothly, the communication algorithm is simple, and there is no need to always receive data during transmission. That is, the device A receives only one bit during transmission, and since that one bit is also the next bit after the start bit, even after detecting a collision, a part of the transmission data is transferred into the reception data. It is not necessary to do so, and it is easy to switch the operation from transmission to reception. The processing of the device B is simple because it is not necessary to detect the collision. As described above, there is a great practical effect.

[Brief description of the drawings]

FIG. 1 is a block diagram of a transmission control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing data on a transmission channel according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a conventional transmission control device.

[Explanation of symbols]

 Reference Signs List 12 device A 13 device B 14 transmission communication path 15, 19 receiving means 16, 20 clocking means 17, 21 transmitting means 18, 22 collision detection bit instructing means 23 1-bit collision detecting means

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[Procedure amendment]

[Submission date] July 9, 2001 (2001.7.9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

5. The method according to claim 1, wherein the collision detection bit is a start bit.
2. The method according to claim 1, wherein the next one bit is used.
Item 5. The transmission control method according to any one of items 4.

6. The first device and the second device are connected.
On a transmission communication path, the first device and the second device
In the transmission control device for transmitting data one-to-one between the first device and the second device,
The bit data indicating the priority on the channel is used as the collision detection bit.
Collision detection bit indicating means for giving an instruction to transmit as
The collision detection bit instructing unit transmits the collision detection bit by the second device.
Detecting the collision detection bit transmitted by the first device
The priority is always set higher than the bit.
Transmission control device.

Wherein said first device, said second high collision detection bi-priority transmitted from the device
Receiving means for receiving the data to which the packet has been assigned, and a collision having a lower priority than the collision detection bit of the second device.
Collision detection bit finger giving an instruction to transmit the collision detection bit
And shows means, collision detection bits instructed by the collision detection bit indicating means
Transmitting means for transmitting data including the collision detection bit data transmitted by the transmitting means
Check the collision detection bit of the data received by the receiving means,
If a mismatch is detected, the transmission by the transmission unit is stopped.
And a one-bit collision detecting means.
Item 7. The transmission control device according to Item 6.

8. A method for determining whether data can be transmitted, and determining whether data can be transmitted.
In the case, give an instruction to transmit data from the transmitting means
8. The method according to claim 7, further comprising a timing unit.
Transmission control device.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Reiko Ueno 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Norimasa Minami 1006 Okadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial F Terms (reference) 5B083 AA08 BB01 EE11 EF04 EF05 GG04 5K032 AA03 CA08 CB00 CC01 CC05 CD05 DA17 EA06

Claims (4)

[Claims] A receiving means for receiving a data transmission message from a two-wire transmission communication path for performing data transmission in an asynchronous start-stop synchronization method; a time counting means for counting a time when there is no received signal by the receiving means; Transmitting means for transmitting a data transmission message after a predetermined time has elapsed from the counting means; and a collision detection bit instruction for giving an instruction to transmit bit data having a low priority on the transmission communication path as a collision detection bit next to the start bit. And a 1-bit collision detecting means for giving an instruction to the transmitting means to determine a collision when receiving data different from the transmission data of the own station in the collision detecting bit from the receiving means and to stop the transmission to the transmitting means. Transmission control device. 2. Receiving means for receiving a data transmission message from a two-wire transmission communication path for performing data transmission in an asynchronous start-stop synchronization method; a time counting means for counting a time when there is no received signal by the receiving means; Transmitting means for transmitting a data transmission message after a predetermined time has elapsed from the counting means; and a collision detection bit for giving an instruction to transmit high-priority bit data on the transmission communication path as a collision detection bit next to the start bit. A transmission control device comprising: an instruction unit. 3. A receiving step of receiving a data transmission message from a two-wire transmission communication path for performing data transmission in an asynchronous start-stop synchronization method, a time counting step of counting a time when there is no received signal by the receiving step, A transmission step of transmitting a data transmission message after a predetermined time has elapsed in a counting step, and a collision detection bit instruction for giving an instruction to transmit bit data having a low priority on the transmission communication path as a collision detection bit next to the start bit. And a 1-bit collision detection step of, when receiving data different from the transmission data of the own station in the collision detection bit from the reception step, giving an instruction to the transmission step to determine a collision and stop transmission. 4. A receiving step of receiving a data transmission message from a two-wire transmission communication path for performing data transmission in an asynchronous start-stop synchronization method; a time counting step of counting a time when there is no received signal in the receiving step; A transmission step of transmitting a data transmission message after a lapse of a predetermined time from a timing step; and a collision detection bit for giving an instruction to transmit high-priority bit data on the transmission communication path as a collision detection bit next to the start bit. A transmission control method having an instruction step.