JPH04310032A - Control system in loop transmission route - Google Patents

Abstract

PURPOSE:To prevent the control operation from falling into an infinite loop due to mis-control. CONSTITUTION:A control station is provided with a period generating circuit 1 to initialize a control signal period and a gate circuit 2 and the gate circuit 2 initializes the control signal and sends it to a transmission line by using a periodic signal outputted from the period generating circuit 1. On the other hand, a controlled station is provided with a latch circuit 3 to latch the control signal initialized periodically to a prescribed state and controlled with an output of the latch circuit 3.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a control system for a loop-type transmission line in which transmission data circulates on the transmission line, in which erroneous control occurs due to data errors on the transmission line in the control signal transmitting circuit and the receiving circuit. The present invention relates to a control method within a loop transmission line that prevents a control signal from becoming an infinite loop within a loop and becoming unrecoverable.

0002

[Prior Art] Conventionally, in this type of loop-type transmission line, control signals are transmitted by installing a protection circuit in the receiving circuit at the controlled station to prevent erroneous control from occurring due to data errors on the transmission line. was.

0003

[Problems to be Solved by the Invention] In the conventional in-loop control method described above, when an error that cannot be prevented by a protection circuit against a data error on the transmission path, such as a burst error, occurs, the control signal is not transmitted within the loop. Since there is no initialization function, there is a problem that if erroneous control occurs once, the control operation will fall into an infinite loop due to the erroneous control.

0004

[Means for Solving the Problems] The loop transmission line control method of the present invention is for controlling one station from among the stations existing in the loop as a control station when controlling the loop in a loop type transmission line. This control station has a period generating circuit and a gate circuit for periodically initializing the control signal, and this gate circuit initializes the control signal with the periodic signal output from the period generating circuit. The controlled station has a holding circuit to hold this control signal, which is periodically initialized and sent, in a constant state, and the control signal is controlled by the output from this holding circuit. It was intended to be received.

[0005]

[Operation] In the present invention, by periodically initializing the control signal that controls the loop on the control station side, when control is not being performed, the control bit may be mistakenly set to the control state due to a data error on the transmission path, etc. Even if this happens, the control station always lowers the signal to logic level "0" for a fixed period T1.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the basic configuration of a control station transmitting circuit section according to an embodiment of the present invention. In FIG. 1, 1 and 2 are a period generating circuit and a gate circuit for periodically initializing a control signal. In this gate circuit 2, the control signal is initialized by a periodic signal output from the period generating circuit 1. It is configured to send the signal to the transmission path.

FIG. 2 is a block diagram showing the basic configuration of a controlled station receiving circuit according to an embodiment of the present invention. In FIG. 2, numeral 3 is a holding circuit for holding in a constant state the control signal that is periodically initialized and sent from the control station, and the controlled station is controlled by the output from this holding circuit 3. is configured to receive.

FIG. 3 is a time chart for explaining the operation of FIGS. 1 and 2, in which (a) shows the control station control signal S1, and (b) shows the initialization timing S.
2, (c) shows the transmission control signal S3/S5, the reception control signal S4, (d) shows the holding circuit holding time T2, and (e) shows the holding circuit output S6. Note that T1 in (b) indicates a constant period, and T2>T1.

Next, the operation of the embodiment shown in FIGS. 1 and 2 will be explained with reference to FIG. First, in a loop-type transmission path, when a control station controls a controlled station, the control station control signal S1 is sent to the transmitter of the control station control signal S1.
The gate circuit 2 is controlled by the initialization timing S2 of a constant period T1 generated by the period generating circuit 1, and a periodically initialized signal is outputted as a transmission control signal S3 to a lower station. On the other hand, the controlled station passes the reception control signal S4 (=S3) as it is and outputs it to the lower station as the transmission control signal S5.
The holding circuit output S6 is output to the internal control circuit as a control signal held at a constant value by the holding circuit 3 in order to control the own station.

Next, timing will be explained using FIG. 3. The control station control signal S1 shown in FIG. 3A is input to the gate circuit 2 at logic level "1" as control information. Then, an initialization timing S2 (see (b) in FIG. 3) defined by a constant period T1 is also input from the period generating circuit 1 to the gate circuit 2. Therefore, this gate circuit 2 takes the conditions of the control station control signal S1 and the initialization timing S2, and outputs the transmission control signal S3 as shown in FIG. 3(c). On the other hand, the holding circuit 3 of the controlled station has a constant period T1 inside the circuit.
It has a holding timing of a holding circuit holding time T2 which is longer than the receiving control signal S4 sent from the upper station.
The holding circuit holding time T2 is determined by the falling timing of
((d) in FIG. 3), and masks the logic level "0" portion of the fixed time T1 that has been initialized by the upper station. Therefore, the holding circuit output S6 can always hold constant control information during control ((e) in FIG. 3), and the internal circuit can be controlled normally.

[0011]

Effects of the Invention As explained above, the loop transmission line control system of the present invention periodically initializes the control signal that controls the loop on the control station side, thereby allowing transmission when control is not being performed. Even if the control bit accidentally enters the control state due to a data error in the
Be sure to keep the signal at the control station at logic level ``0'' for a certain period T1.
”, which has the effect of preventing falling into an infinite loop of erroneous control.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of a control station transmitting circuit section according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the basic configuration of a controlled station receiving circuit according to an embodiment of the present invention.

FIG. 3 is a time chart for explaining the operations of FIGS. 1 and 2;

[Explanation of symbols]

1 Period generation circuit 2 Gate circuit 3 Holding circuit

Claims (1)

[Claims] [Claim 1] When controlling the loop in a loop-type transmission line, one station among the stations existing in the loop is determined as a control station, and a control signal is periodically initialized in this control station. The gate circuit initializes the control signal using the periodic signal output from the period generation circuit and sends it to the transmission path. A control system in a loop transmission line, characterized in that it has a holding circuit for holding this control signal initialized and sent in a constant state, and is controlled by the output from this holding circuit. .