JPS62292040A - Loop bus control system - Google Patents

Abstract

PURPOSE:To reduce a waiting time, and to improve transmission efficiency even when a large number of information frames are generated, by subsisting plural control frames on a loop bus, according to a condition derived from relation between a destination address and its own station address. CONSTITUTION:It is assumed that the relative position of a data processor having a destination station address in a loop bus 1, from its own station, is separated by half cycle of the bus 1 in the running direction of a frame, like a data processor 2n. In this case, at the time of detecting the reception of the control frame by a frame reception circuit 3, the reception of the control frame is stored by a control frame storage circuit 4. The next control frame is waited, and at the time of receiving the control frame, the information frame transmitted from an information frame transmission circuit 8 is transferred to the bus 1 by controlling a transmission frame switching circuit 9. At the time of completing the transmission of the information frame, the control frame transmitted from a control frame transmission circuit 7 is trnasferred to the bus 1 by controlling the circuit 9.

Description

[Detailed Description of the Invention] Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a loop bus control system, and in particular to information processing in a loop bus to which a plurality of data processing devices having unique station addresses are connected. The present invention relates to a loop bus control method in which frame transmission is triggered by reception of a control frame.

[Conventional technology]

Conventionally, in a loop bus to which a plurality of data processing devices having unique station addresses are connected, when one of these data processing devices attempts to transmit an information frame onto the loop bus, It waits for the reception of the only control frame existing on the loop bus, and uses the reception of this control frame as an opportunity to transmit an information frame.

[Problem that the invention seeks to solve]

In the conventional loop bus control method described above, there is only one control frame on the loop bus that triggers the transmission of information frames, so if one data processing device is transmitting, Even if there is a section in which no frames are flowing, other data processing devices cannot transmit information frames, so the more information frames that flow on the loop bus, the longer the waiting time and the lower the transmission efficiency. There is a drawback.

[Means for solving problems]

In the loop bus control method of the present invention, a plurality of data processing devices, each of which is assigned a unique station address, are connected via a loop bus according to predetermined rules, and data is exchanged between the data processing devices. In a loop bus control method in which an information frame is transmitted triggered by reception of a control frame that constantly circulates within the loop bus, each data processing device includes a frame receiving circuit that receives the control frame and a frame receiving circuit that transmits the control frame. a control frame transmission circuit, an information frame transmission circuit that transmits the information frame, a transmission frame switching circuit that switches between the control frame transmission circuit and the information frame transmission circuit, and a control frame storage circuit that stores reception of the control frame. and,
A comparison of a local station address generation circuit that generates a station address assigned to the local data processing device, and a destination station address of an information frame in the information frame transmission circuit and a local station address generated by the local station address generation circuit. and processing means for causing a plurality of the control frames to exist in the loop bus according to the comparison result of the comparison circuit.

〔Example〕

Next, the present invention will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram showing an embodiment of the loop bus control method of the present invention, and FIG. 2 is a diagram showing an example of a frame format flowing on the loop bus in FIG. 1.

In FIG. 1, a plurality of data processing devices 2a.

2b, 2c, to 2n are connected to the loop bus 1.

These data processing devices 2a, 2b, 2c.

~2n are each assigned a unique station address,
They are connected so that the station address values are in ascending order with respect to the frame flow direction.

In addition, in FIG. 2, the frame has a flag pattern F,
Destination station address DA, own station address SA.

It consists of a control field C, data D, and a frame check sequence FCS.

Next, the operation of this embodiment will be explained with reference to FIG. 2.

For example, the information frame transmitting circuit 8 of the data processing device 2a
When attempting to transmit an information frame from a computer, the comparison circuit 5 compares the local station address SA generated by the local station address generation circuit 6 and the destination station address DA of the information frame in the information frame transmission circuit 8, and Station address D
If the relative position of the data processing device with A from the own station in the loop bus 1 is closer than half a circle of the loop bus 1 in the frame flow direction, as in the case of the data processing device 2C, reception of the control frame is controlled by the frame receiving circuit. 3, the transmission frame switching circuit 9 is controlled,
The information frame transmitted from the information frame transmitting circuit 8 is passed onto the loop bus 1.

When the transmission of this information frame is completed, the transmission frame switching circuit 9 is controlled to flow the control frame transmitted from the control frame transmission circuit 7 onto the loop bus 1.

Furthermore, if the relative position of the data processing device having the destination station address DA from the own station within the loop bus 1 is farther than half a circle of the loop bus 1 in the frame flow direction, as is the case with the data processing device 2n, the control frame When the frame reception circuit 3 detects reception, the control frame storage circuit 4 stores the fact that the control frame has been received. Then, it waits for a control frame again, and when the next control frame is received, it controls the transmission frame switching circuit 9 to flow the information frame transmitted from the information frame transmission circuit 8 onto the loop bus 1. Once this information frame has been sent,
The transmission frame switching circuit 9 is controlled to flow the control frame transmitted from the control frame transmission circuit 7 onto the loop bus 1. Furthermore, the control frame is sent to the loop bus 1 again at the timing when the control frame has made a half-circle around the loop bus 1.

〔Effect of the invention〕

As explained above, the loop bus control method of the present invention allows multiple data processing devices to which unique station addresses are assigned to transmit multiple control frames according to conditions derived from the relationship between the destination station address and the local station address. By placing it on the loop bus, it becomes possible for a large number of data processing devices to transmit information frames at the same time within the section where data is not flowing on the loop bus.
Even if the number of information frames increases, the increase in waiting time is small and the transmission efficiency does not deteriorate.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the loop bus control method of the present invention, and FIG. 2 is a diagram showing an example of a frame format flowing on the loop bus in FIG. 1.

Claims (1)

[Claims] A plurality of data processing devices, each of which is assigned a unique station address, are connected via a loop bus according to a predetermined rule, and information frames exchanged between each data processing device pass through the loop bus. In a loop bus control method in which transmission is triggered by the reception of control frames that are constantly rotating, each data processing device includes a frame reception circuit that receives control frames, a control frame transmission circuit that transmits the control frames, and a control frame transmission circuit that transmits the control frames. An information frame transmission circuit that transmits frames, a transmission frame switching circuit that switches between the control frame transmission circuit and the information frame transmission circuit, a control frame storage circuit that stores reception of the control frames, and an information frame transmission circuit that is allocated to the own data processing device. a comparison circuit that compares the destination station address of the information frame in the information frame transmission circuit with the own address generated by the own address generation circuit; and processing means for causing a plurality of the control frames to exist in the loop bus according to a comparison result.