JPS63119345A - By-pass control circuit - Google Patents

Abstract

PURPOSE:To prevent loss of tokens and frames by resetting a transmission request and invalidating the terminating function of a repeater circuit so that the output signal of a repeater circuit and that of a by-pass circuit coincide with each other and switching the by-pass circuit thereafter. CONSTITUTION:A by-pass switching control circuit 2 turns on a by-pass control signal BCTL for a certain time when detecting that a by-pass indicating signal BPS is turned on. A transmission control circuit 5 resets all transmission requests, and thereby, a token is transmitted if the taken is held or the token acquiring operation is performed. A reception control circuit 4 invalidates the frame terminating indication transmission function of a repeater circuit 3 to allow the output of the circuit 3 and the output of a by-pass circuit 1 to coincide with each other. After a prescribed time, the by-pass switching control circuit 2 turns off the by-pass control signal BCTL and turns on a by-pass switching signal BSEL. A by-pass changeover switch 6 is so switched that the output from the by-pass circuit 1 is transferred to a frame transmission circuit 9 as transmission data.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a token passing system in which a plurality of nodes are connected in series to a ring-shaped transmission path, and communication is performed between each node using tokens representing transmission rights. In particular, the present invention relates to a node bypass control circuit.

[Conventional technology]

Conventionally, this type of bypass control circuit has a switch, relay, electronic circuit switch, etc., and when a factor that causes the output node to switch to the bypass state occurs, a direct path is established from the receiving terminal of the node to the transmitting terminal. In order to do this, switching was done using switches or relays.

[Problem that the invention seeks to solve]

The above-described conventional bypass control circuit is configured to transmit data when a frame containing a token or a token exists on a repeater circuit that passes received transfer frames, or from the own node, in a node that transitions to a bypass state. If a switch is made to the bypass state when there are no tokens on the ring-shaped transmission path because the tokens were captured in the past, the disadvantage is that the tokens or frames will be lost and other communications will be affected.

[Means for solving problems]

The bypass control circuit of the present invention includes a bypass switching control circuit that sends out a bypass control signal for a predetermined period of time when a bypass instruction signal is detected, and then sends out a bypass switching signal, and a bypass switching control circuit that resets all transmission requests when the bypass control signal is detected. a transmission control circuit that transmits the token if there is a captured token in the node and prevents the token from being captured even if the token is detected again; and a transmission control circuit that transmits a frame termination instruction when the bypass control signal is detected. A reception control circuit that disables the function, a repeater circuit that delays and outputs the received transfer frame, or continues to terminate the input frame according to a termination instruction from the reception control circuit until the end of the frame, and a repeater circuit that outputs the received transfer frame with a delay until the end of the frame. a bypass control circuit that transfers with a delay of the same delay time as the repeater circuit, and a frame transmission circuit that selects the transfer frame from the bypass circuit and the transmission signal from its own node by a bypass switching signal from the bypass switching control circuit. and a bypass selector switch that transmits data to the line via the

[For production]

In this way, the bypass switching control circuit resets the transmission request while sending the bypass control signal for a predetermined time based on the bypass instruction signal, and if there is a token in the node, sends the token, and even if a token is detected again, the token is not sent. The termination function of the repeater circuit is disabled so that the output signal of the repeater circuit and the output signal of the bypass circuit match, and then the bypass switching signal is used to switch to the bypass circuit, thereby changing from the normal operating state to the bypass state. The loss of tokens and frames in the transition to is prevented.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the bypass control circuit of the present invention. The upper interface circuit 11 is a circuit that controls the transmission and reception of data between the upper processing device and the link control circuit 10, which controls transmission rights (tokens) and transmission procedures for communicating with other nodes. It has an interface circuit 11, a reception control circuit 4, and a transmission control circuit 5. Reception control circuit 4
When receiving the received data RO from the frame receiving circuit 8, the transmitting control circuit 5 analyzes the frame and transfers the data or provides received frame information to the link control circuit 10 depending on the frame type. It receives transmission data or a transmission frame request and transfers the transmission data to the transmission changeover switch 7. The repeater circuit 3 has the function of delaying the received data RD received from the frame receiving circuit 8 and forwarding it to the transmission changeover switch 7, and terminating the frame existing in the repeater circuit 3 until the end of the frame according to instructions from the receiving control circuit 4. The transmission changeover switch 7, which has a continuous function, selects the transmission data from the repeater circuit 3 and the transmission control circuit 5 and transfers it to the bypass changeover switch 6. The bypass circuit 1 transfers the received data RD from the frame receiving circuit 8 to the bypass changeover switch 6 with the same delay time as the repeater circuit 3. The bypass switching control circuit 2 receives a bypass instruction signal BPS.
When the bypass control signal BCTL is received, the bypass control signal BCTL is turned on for a certain period of time for the bypass circuit 1 and the repeater circuit 3, and after the bypass control signal BCTL is turned off, the bypass switching signal BSEL is turned on to instruct the bypass changeover switch 6 to switch. . The bypass changeover switch 6 selects the transmission data from the bypass circuit 1 and the transmission changeover switch 7 according to the bypass changeover signal BSEL, and selects the transmission data from the bypass circuit 1 and the transmission changeover switch 7,
Sends frames to the line via

Next, the operation when the bypass instruction signal BPS is turned on in a normal state (non-bypass state) will be described. When the bypass switching control circuit 2 detects that the bypass instruction signal BPS is turned on, it turns on the bypass control @ number BCTL for a certain period of time. The transmission control circuit 5 includes bypass control @No. BCTI,
When detecting the on state, all transmission requests are reset, and if the token is held or the token is captured, the I-kun is sent. When the reception control circuit 4 detects that the bypass control signal BCTL is turned on, it disables the frame termination instruction sending function to the repeater circuit 3, thereby making the output of the repeater circuit 3 and the output of the bypass circuit 1 coincide. After the minimum required time has elapsed until the token transmission operation is completed and the outputs of the repeater circuit 3 and the bypass circuit 1 match, the bypass switching control circuit 2
The bypass control 04 signal ECTL is turned off and the bypass switching signal BSEL is turned on. When the bypass changeover switch 6 detects that the bypass changeover signal BSEL is turned on,
The output from the bypass circuit 1 is switched to be transferred to the frame transmission circuit 9 as transmission data TO. FIG. 2 shows a timing chart at this time.

〔Effect of the invention〕

As explained above, the present invention enables a node to be placed in a bypass state when a failure occurs in the node, when maintaining some functions of the node, or when it becomes necessary to disconnect the node from the system. If the node holds the token at the time of migration, it transmits the token, resets all transmission requests of the node so that it will not capture the token even if it detects the token again, and outputs the repeater circuit of the node. By disabling the termination function of the repeater circuit so that the signal and the output signal of the bypass circuit match, and by suspending the operation of switching to the bypass circuit side until the above operations are completed, token loss is prevented and token passing is prevented. This has the effect of improving system processing efficiency, such as eliminating system restarts and call losses.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the bypass control circuit of the present invention, and FIG. 2 is a control signal BPS in FIG. 1. This is a timing chart of BC:TL and BSEL. 1...Bypass circuit, 2...Bypass switching control circuit, 3...
Repeater circuit, 4... Reception control circuit, 5... Transmission control circuit, 6... Bypass changeover switch, 7...
Transmission changeover switch, 8...Frame reception circuit, 9...Frame transmission circuit, 10...Link control circuit, 11...Upper interface circuit, TO・
...Transmission data, RD...Reception data, BPS...Bypass instruction signal, BCTL...Bypass control signal, BSEL...Bypass switching signal.

Claims (1)

[Claims] In a token passing system in which a plurality of nodes are connected in series to a ring-shaped transmission path and communication is performed between each node using tokens representing transmission rights, it is possible to A bypass control circuit that sets the node to a bypass state when it is necessary to temporarily disconnect the node from the system for maintenance of a section function, etc., and when a bypass instruction signal is detected, the bypass control signal is set to a predetermined value. a bypass switching control circuit that transmits a signal for a certain amount of time and then transmits a bypass switching signal; upon detecting the bypass control signal, resets all transmission requests, and if there is a token captured by the node, transmits the token; A transmission control circuit that prevents the token from being captured even if the token is detected again; a reception control circuit that disables the frame termination instruction sending function when the bypass control signal is detected; and a reception control circuit that delays and outputs the received transfer frame. , or a repeater circuit that continues to terminate frames inputted by a termination instruction from the reception control circuit until the end of the frame; a bypass circuit that delays the received transfer frame by the same delay time as the repeater circuit; and from the bypass circuit. A bypass control circuit comprising: a bypass changeover switch that selects a transfer frame of 1 and a transmission signal from its own node according to a bypass changeover signal from the bypass changeover control circuit, and transmits the selected frames to a line via a frame transmission circuit.