JPS60114048A - Data transfer method - Google Patents

Abstract

PURPOSE:To eliminate meaningless occupation of bus by sending out dummy data on the bus intentionally when it is under a busy condition, and suspending the transmission immediately by a transmission side device which detects collision due to these dummy data. CONSTITUTION:In this method, (a) monitor step, (b) transmission step, (c) collision monitor step, (d), waiting step, (e) reception data input step (condition: no hindrance in data fetching), (f) response information transmission step are all the same as in the conventional device, but when conditions are not satisfied at the (e) step and the device is busy, dummy data are sent out. That is, when the device, which detects that address is coincident to its own address at the waiting step, is troubled in fetching in data following the above address, the device sends out data 4 following address and dummy data 7 generating collision on a bus (1-1). These dummy data 7 are detected at the (c) step, followed by transmission suspension 9, thereby preventing meaningless occupation of the bus (1-1) and action by the transmission side device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a data transfer method when a plurality of devices share a transmission path and transfer data between the devices.

[Prior art]

FIG. 1 is a block diagram showing such a transfer device.
-1) is a common transmission path (hereinafter abbreviated as bus, but it may also be a transmission path using a wireless line), (1-2) is a terminal device, and terminal device (1-2) is a bus (1-2). 1) so that the signal is not reflected from the end. (2-1),
(2-2) and (2-3) are respectively buses (1-1)
It is a device that connects to the device.

Figure 2 is a format diagram showing the conventional method.
a) is a signal sent from the sending device, fbl in the figure is a signal sent from the receiving device, (31 is the destination address, (41 is the transmission data, and (51 is response information).

(6) indicates a data line on the transmission path (1-1').

Each of the devices (2-1), (2-2), and (2-3) is given a unique address.

The operation will be explained below.

(a) Monitoring stage Each device monitors whether the bus (1-1) is in a used state or an unused state.

(b) Transmission stage When a device that has data to be sent is
-1) starts feeding when it is detected that it is unused. When one device starts transmitting, other devices know that bus (1-1) is in use, but multiple devices detect that bus (1-1) is not in use. If they start transmitting at the same time, a signal collision will occur on the bus (1-1). Transmission is started using a procedure that minimizes the occurrence of such collisions, but since this method is conventionally known and has no direct bearing on the present invention, its details will be omitted.

In the transmission stage, the signals sent on the bus (], -1,) are destination address information (31) and subsequent transmission data (41), as shown in FIG.

(c) Collision monitoring stage The device transmitting in the transmission stage receives the signal on the bus (1-1), and detects that there is a signal other than the signal sent by itself in the received signal, and the device sends the signal. It monitors whether there is a collision with a signal. When a collision is detected, all devices colophoning transmissions related to the collision must leave only one device behind, or all devices must interrupt their transmissions.

To simplify the explanation below, it is assumed that all transmitting devices that detect a collision interrupt their own transmission.

B) Standby stage Each device receives the destination address sent out on the bus (1-1) and monitors whether this destination address matches its own address.

(E) Received data input stage The device that detects that the destination address matches its own address in the standby stage takes in the following data into the device.

That is, it is input to a memory circuit within the device.

(to) Response information sending stage The data captured in the received data input stage is checked for errors, and after the sending data +41 is completed, the response information (5) indicating whether or not the input has been completed without error is sent to the bus (1- 1) Send upward.

Since the conventional device operates as described above, in the relationship between the above-mentioned (a) standby stage and (e) received data input stage, □
If the device that detects that the destination address matches its own address is in a busy state that prevents it from receiving subsequent data, it waits for the end of the sent data +41 and sends the message using response information (5). It is necessary to notify that the data has not yet been completed, and during this time the bus (1-1) is occupied unnecessarily, and the device on the data sending side has to perform unnecessary operations.

[Summary of the invention]

This invention was made to eliminate the drawbacks of conventional ones such as the above fltj, and in this invention, a device that detects that a destination address matches its own address,
When the device is in a busy state where subsequent data cannot be taken in, dummy data is intentionally sent onto the bus (1-1), and the sending device, which detects a collision causing this dummy data, immediately interrupts the transmission. It was designed to help children have children.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a format diagram showing an embodiment of this invention.
Figure 3(a) shows the signal sent from the transmitting device, and tb in the same figure.
) indicates a signal sent from the receiving device, O\ The same symbol as in Figure 2 indicates the same or corresponding signal or the same part, (7) is dummy data, 181 is the part where collision is detected, (9 ) is the transmission interruption point.

Also in the method of this invention, (a) monitoring stage, (b) transmission 1M stage, □ (c) collision monitoring stage, d) standby stage, (e) received data input stage (condition: no problem in data acquisition. The response information sending step is the same as in conventional devices, but if the condition is not satisfied in step (e) and the device is in a busy state, dummy data is sent as step (g). be exposed. In other words, if device a detects that the destination address matches its own address in the standby stage of (g) dummy data sending stage), if it interferes with the acquisition of data following the destination assist, it will send the data to the destination address. The dummy data that causes a collision with the following data 14) (
71 onto the bus (1-1).

This dummy data (71) is detected at the crash monitoring stage (c) and the transmission is interrupted (9), so the bus (1-1) is unnecessarily occupied and the sending device performs unnecessary operations. It can be prevented.

〔Effect of the invention〕

As described above, according to the present invention, regardless of whether the receiving IHj+ is busy, the transmitting side continues to send data via the bus (
The disadvantage that 1-U is wasted can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a system for a data transfer device, FIG. 2 is a format diagram showing the conventional method, and FIG. 3 is a format diagram showing the method of this invention. . (1-1)...Bus, (2-L), (2-2L(2-
3)・Song・Each installation[, +31...Destination address,
(41...Transmission data, (5)...Response information, (7
)...Dummy data. Note that the same reference numerals in each figure indicate the same or corresponding parts. Fig. 1 Fig. 2 m 1 hour Fig. 3 7 --〉Time

Claims (1)

[Scope of Claims] In a data transfer method where a plurality of devices share a transmission path and transfer data between the devices, a monitoring step in which each device of the plurality of devices monitors the usage state of the transmission path. When a device that has data to be sent to the transmission path detects that the transmission path is unused during the monitoring stage, the data to be sent is prefixed with a destination address indicating the address of the destination device. a transmission step in which each device of the plurality of devices constantly monitors whether or not the destination address in the signal sent to the transmission path matches its own address; A device that detects that the above destination address matches its own address at the receiving stage,
If there is no problem in importing the data following the above destination address, the reception data manual stage where the data is imported, and the presence or absence of errors in the data imported at this reception data input stage is notified to the data sending device. If the device detects that the destination address matches its own address in the standby phase and has trouble taking in the data following the destination address, it will collide with the data following the destination address. a dummy data sending step of sending out dummy data that generates a
A collision monitoring stage in which the signal on the transmission path is received and monitors whether a signal other than the one transmitted by the self exists and collides with the signal transmitted by the self. Immediately when a collision is detected in this collision monitoring stage. A data transfer method comprising a transmission interruption step for interrupting transmission.