JPH05218910A - Abnormal bit signal transmitting method and transmitter therefor - Google Patents

Abstract

PURPOSE:To inform other node of an abnormal state at a point of time as fast as possible independently of a token by sending abnormal bit signals by the twice of a time capable of detecting the abnormal bit signal in addition to a frame period time length. CONSTITUTION:A switching circuit 2 for switching a signal is controlled so that a driving circuit 4 sends the abnormal bit signal by twice of a time capable of detecting the error bit signal generated by an error bit pattern generating circuit 1 from other node at least in addition to the time of a normal frame since an abnormality detection signal is fed to the driving circuit 4 from a detection circuit (not shown) when a node including the transmitter is faulty. The error bit signal sent in such a manner is transmitted to other node via a transmission output circuit 5a and a transmission line 5b. The other node fetches the signal via a transmission input circuit 5c and an error bit pattern detection circuit 6 and a frame reception circuit 7 receive the signal. The frame reception circuit 7 receives a normal frame signal normally and the error bit pattern detection circuit 6 detects the error bit pattern in the abnormal state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transmitting an abnormal bit signal in a communication system using a token bus system and a transmission device therefor.

[0002]

2. Description of the Related Art Conventionally, a node connected to a token bus using a token is constructed so that a frame can be transmitted to a transmission line only while a token is held.

[0003]

However, in such a conventional system, when a serious failure occurs in a node, it is necessary to inform other nodes of the abnormal state.
There was a problem that the abnormal state could not be transmitted to another node until the token came to that node.

The present invention has been made in view of such circumstances, and is to notify other nodes of abnormality in the shortest possible time.

[0005]

In order to solve such a problem, a first aspect of the present invention is to add the abnormal bit signal at least twice as long as the abnormal bit detectable time at the receiving side in addition to the frame signal time. Is to be transmitted. A second invention is a normal frame generation circuit for generating a normal frame signal including a token, an abnormal bit pattern generation circuit for generating an abnormal bit signal indicating an abnormal state, a normal frame generation circuit output and an abnormal bit pattern generation circuit output. And a switching circuit for switching and outputting the abnormal bit pattern generation circuit when an abnormal condition is detected, and in addition to the length of the normal frame signal, an extra signal is transmitted at least twice as long as the number of detectable bits of the abnormal bit. And a drive circuit for controlling the switching circuit.

[0006]

According to the present invention, in addition to the time of the normal frame bit, the extra length is transmitted for a time twice as long as the abnormal bit can be detected. Even if it collides with the signal from the other node, the abnormal bit is still sent even after the transmission from other nodes is completed, and since it is sent at least for the time that the receiving side can detect as an abnormal bit, Can detect the abnormal bit.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the present invention. An abnormal bit pattern generation circuit 1 notifies an abnormal bit signal to another node when that node becomes abnormal. Is constantly occurring. Further, the normal frame generation circuit 3 includes a token and generates a frame signal to be transmitted at a normal time. These are switched by the switching circuit 2 and either one of them is sent out.

When the node including this device becomes abnormal, an abnormality detection signal is supplied to the drive circuit 4 from a detection circuit (not shown), so that the drive circuit 4 switches at least other signals in addition to the normal frame time. The node 2 controls the switching circuit 2 so as to send out the abnormal bit signal for an extra time twice as long as the time when the abnormal bit signal generated by the abnormal bit pattern generation circuit 1 can be detected.

The abnormal bit signal thus transmitted is transmitted to another node via the transmission output circuit 5a and the transmission line 5b. At the other nodes, the signal is transmitted to the input circuit 5
It is captured via c and received by the abnormal bit pattern detection circuit 6 and the frame reception circuit 7.

Therefore, the normal frame signal is received by the frame receiving circuit 7 when normal, and the abnormal bit pattern is received by the abnormal bit pattern detection circuit 6 when abnormal.

The abnormal bit signal is transmitted in excess of the normal frame signal as described above. The extra time is at least twice as long as another node can detect the abnormal bit pattern. Therefore, even if the abnormal bit signal being transmitted collides with the transmission signal from another node, the abnormal bit signal is received by another node during the period in which the abnormal bit signal is being transmitted.

FIG. 2 is a flow chart showing the above operation. When it is detected in step 100 that an abnormal state has occurred, the switching circuit 2 connects the output to the abnormal bit pattern generating circuit side in step 101, and in step 102, the number of detectable bits is twice the maximum frame length. Keep that connection for a period of time.

Then, in step 103, the normal frame generation circuit is selected, and in step 104, it is detected whether or not the abnormal state is restored. If it is restored, the process returns to step 100.

[0014]

As described above, according to the present invention, the abnormal bit signal is added to the frame period length, and the abnormal bit signal is transmitted for twice as long as the time period in which the abnormal bit signal can be detected. Even if the signal collides with the transmission from another node, there is always a time when the abnormal bit signal can be detected, and as a result, it has the effect of being able to notify the abnormal state to other nodes at the earliest possible time regardless of the token. ..

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the apparatus of FIG.

[Explanation of symbols]

 1 Abnormal Bit Pattern Generation Circuit 2 Switching Circuit 3 Normal Frame Generation Circuit 4 Driving Circuit 5a Transmission Line Output Circuit 5b Transmission Line 5c Transmission Line Input Circuit 6 Abnormal Bit Pattern Detection Circuit 7 Frame Reception Circuit

Claims (2)

[Claims] 1. An abnormal bit signal transmission method for transmitting an abnormal bit signal indicating an abnormal state to a device connected to a transmission system having a transmission right only by a device receiving a token included in a frame signal, wherein the frame signal time is In addition to the above, the abnormal bit signal transmission method further comprises transmitting the abnormal bit signal at least twice as long as the abnormal bit detectable time at the receiving side. 2. A normal frame generation circuit for generating a normal frame signal including a token, an abnormal bit pattern generation circuit for generating an abnormal bit signal representing an abnormal state, an output of the normal frame generation circuit and an output of the abnormal bit pattern generation circuit. And a switching circuit for switching and outputting the abnormal bit pattern generation circuit output signal when an abnormal state is detected, in addition to the length of the normal frame signal, at least twice as long as the abnormal bit detectable bit number is additionally transmitted. And a drive circuit for controlling the switching circuit as described above.