JPS62104339A - Node station bypassing method for loop network - Google Patents

Abstract

PURPOSE:To perform transmission without any error by detecting an ineffective data area in a transmit frame entering a node station and then carrying out the bypassing operation of a node station when the node station is bypassed. CONSTITUTION:When an ineffective data area in the transmit frame enters a multiplexing part 10 completely after a power-down signal is outputted, that is detected by an ineffective data area detecting circuit 13, which sends out a detection output signal to a switching part 12. Consequently, the switching part 12 operates and only the repeating operation of a repeating part 9 is carried out at the node station, so that the bypassing operation is completed. Consequently, data is transmitted through a transmission line 7, the repeating part 9, and a transmission line 8 and the multiplexing part 10 is bypassed. In this case, the bypassing operation is performed when ineffective data in the transmit frame enters the multiplexing part 10, so the ineffective data is erased, but necessary data remains as it is, so that the data transmission is performed accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a node station bypass method for loop networks, particularly channel multiplexed loop networks.

[Prior Art] As shown in FIG. 3, a channel multiplexed loop network divides a transmission frame into channels 2 of, for example, 8 to 10 bits, and assigns one line between terminals to each channel to transmit data. This is the method to do it.

In order for this loop network to work properly,
It is necessary to keep all node stations that make up the loop in an operational state (power or ON state) at all times.
If the power of one node station were turned off, the loop would be broken and data transmission would become impossible.

Conventionally, in order to solve this problem, as shown in FIG.
A system has already been proposed in which power is supplied from a local power source 6, and even if the node station's power is turned off, only relay transmission is ensured and the loop is not broken.

[Problems to be Solved by the Invention] However, when this method is applied to a channel multiplexed loop network, the transmission path 7, the relay receiving section 9,
By turning off the power supply 14 of the node station where data was flowing through the multiplexing section 10, the relay transmitting section 9, and the transmission line 8, only the relay section 9 is operated with the power supply 6 from the loop power supply line 5. The multiplexer 10 will be bypassed and the transmission line 7, relay unit 9, and transmission line 8 will be connected, but the moment the bypass is made, the data passing through the multiplexer 10 will be lost, causing errors in data transmission. There were some drawbacks that could arise.

In order to improve this drawback, it has been proposed to include the power supply part from the loop not only to the relay part but also to the multiplex part, but in this case, the power consumption of the bypass node increases and The drawbacks are that the power supply device is large and the power supply line is also thick.

Note that 12 is a switching section, 16 is a power line, and 11 is a terminal interface section.

[Means for Solving the Problems] An object of the present invention is to solve the above-described drawbacks of the prior art and to provide channel multiplexing that prevents data on a loop transmission path from being lost even when a node station is bypassed. The purpose of the present invention is to provide a node station bypass method for type loop networks.

That is, the gist of the present invention is to construct a loop network by sequentially connecting each node station that performs data input/output control with a terminal device using a transmission line, and to construct a loop network using a fixed length frame. In a channel multiplexed loop network in which a transmission frame divided into a plurality of channels circulates at a constant speed, an invalid data area corresponding to the delay amount of the node station is provided at the end of the channel multiplexed transmission frame, and the node station In the node station bypass method for a loop network, when bypassing, the node station bypass operation is performed after detecting that the invalid data area of the transmission frame has entered the node station.

[Example] A specific example of the present invention will be further described with reference to FIGS. 1 and 2.

FIG. 1 shows the format of a transmission frame used in the present invention, where 1 is a frame header,
This is followed by a plurality of channels 2 divided into 8~'l Qbits, and an invalid data area 3 is provided roughly at the end, forming a transmission frame of T time with a pause.

Here, the difference between the transmission frame of this embodiment and the transmission frame used conventionally is that, as is clear from a comparison of FIG. 1 and FIG. This is because area 3 is the treasure.

This invalid data area time t must be set so that t≧(delay time of the multiplexing section of the node station).

The bypass operation when using this transmission frame will be briefly described with reference to FIG. 2.

Reference numeral 4 indicates a transmission line, which is a composite cable of a power supply line and a loop transmission line, and a power supply line 5 is a relay section Kawagiri where power is supplied from a point on the loop. 6, and the relay power supply 6 supplies power to the relay section 9.

On the other hand, the loop transmission line 7 is connected to the relay reception section 9, and then connected to the next node station via the multiplex section 10, the relay transmission section 9, and the transmission loop transmission line 8. A loop network is constructed by sequentially connecting them.

In addition, 12 is a switching section, 11 is a terminal interface section, 1
4 is a node station power supply, and 13 is an invalid data @ area detection circuit.

The circuit of this embodiment differs from conventional circuits in that when the power of the node station is turned off, the node station issues a power-down signal, and that an invalid data area is detected from the transmission frame entering the multiplexing section. The point is that an invalid data area detection circuit is provided.

That is, when the power supply 14 of the node station is turned off, a power down signal 15 is generated from the power supply unit of the node station, and the signal is transmitted to the switching section 12.

Even if the power is turned off at this point and a power down signal is issued,
The power supply output is kept at that voltage for a while, and the circuit operates normally.

However, when the invalid data area in the transmission frame completely enters the multiplexing section 10 after the power down signal is output, the invalid data area detection circuit 13 detects this, and a detection output signal from the invalid data area detection circuit 13 is sent to the switching section 12. As a result, the switching unit 12 operates, and the node station only performs the relay operation of the relay unit 9, completing the bypass operation.

As a result, data is transmitted through the transmission path 7, the relay section 9, and the transmission path 8, and the multiplexing section 10 is bypassed.

In this case, the bypass operation occurs when invalid data of the transmission frame enters the multiplexer 10, so although the invalid data is lost, the necessary data remains, allowing accurate data transmission. .

[Effects of the Invention] As explained above, in the present invention, during bypass operation, data in the invalid data area is lost, but valid data in the frame is not destroyed at all. Since only the relay part is required to supply power from the bypass node, the power consumption of the bypass node is small, the power supply device can be small, and the power supply line is thin, which is a good advantage. There is great value.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the format of a transmission frame used in the bypass method of the present invention, FIG. 2 is a block diagram showing an example of a circuit implementing the bypass method of the present invention, and FIG. FIG. 4 is an explanatory diagram showing an example of the format of a transmission frame, and FIG. 4 is a block explanatory diagram showing a conventional circuit. 1: Frame header 2: Channel 3: Invalid data area 4: Power supply line 5: Power supply line 6: Relay unit power supply 7: Loop transmission line (reception) 8: Loop transmission line (transmission) 9: Relay unit 10: Multiplex unit 11: Terminal interface unit 12: Switching unit 13: Invalid data area detection circuit 14: Node station power supply 15: Power down signal 16: Power line agent Patent attorney Fi Fujio Fujio + 2 diagrams

Claims (1)

[Claims] (1) Each node station that performs data input/output control with a terminal device is sequentially connected with a transmission line to form a ring to form a loop network, and the loop is divided into fixed-length frames into multiple channels. In a channel multiplexed loop network in which transmission frames circulate at a constant speed, an invalid data area corresponding to the delay amount of the node station is provided at the end of the channel multiplexed transmission frame, and when bypassing the node station, the node station A node station bypass method for a loop network, characterized in that a node station bypass operation is executed after detecting that an invalid data area of a transmission frame has entered.