JPS60186153A - Clock supply system of looped network - Google Patents

Abstract

PURPOSE:To stabilize clock synchronism characteristics by allowing a clock station to supply a clock signal to a looped transmission line in a protection time. CONSTITUTION:The clock station 7 and plural node stations 1-6 are connected through the looped transmission line 8; and the clock station 7 performs polling control within a specific period T0 and the respective node stations stop transmission control for the predetermined protection time Tg at the end of the period T0. In this looped network ststem, the clock station 7 supplies the clock signal to the looped transmission line for the protection time Tg. The respective node stations 1-6 extract a clock from the clock signal, so the clock synchronism never becomes unstable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a clock supply system f from a clock station to each node station in a loop network.

(Prior art and its problems) It is composed of a clock stay 7g/ and a plurality of node stations, and the clock station performs polling control within a certain period, and at the end of the period, each station is As one of the loop-shaped nets that stop the transmission, Tokutsumugi No. 58-0554J,
There are items listed in 8.

The configuration of such a loop network and work is shown in FIG. The network of FIG. 1 consists of a clock station 7 and node stations 1, 2, 3, 4.5 and 6, which are connected by a loop 8. The clock station 7 has a constant period T as shown in FIG. The synchronizing signal 8YN is supplied to the loop 8, and polling control is performed using the trigger signal T-G during the cycle.

Each note stage sends out its own packet P K T in response to the polling control of the clock station 7 . However, each period ゛l゛. At the rear end, the protection period 'Rice Snacking Stage Day' stops transmitting to prevent the next synchronization signal 8YN from being interfered with.

Therefore, no signal is supplied to the loop transmission line during the protection time. On the other hand, each station must maintain clock synchronization in order to communicate via the loop-shaped transmission path. This clock synchronization is achieved by extracting the signal on the loop-shaped transmission path, but if there is a situation where the signal is not supplied as in such a network, there is a problem that the clock synchronization becomes unstable. There is.

(Object of the Invention) An object of the present invention is to connect multiple loop-shaped networks to a loop-shaped transmission line, and to perform polling control within a fixed cycle, and to perform polling control at the rear end of the cycle. A clock supply for a loop network in which a node station stops transmitting control during a guard time, wherein the clock station supplies a clock signal to the loop transmission line during the guard time. Method 〇 (Embodiment) In the loop-shaped network clock supply method of the present invention, a clock station supplies a clock signal to a loop-shaped transmission line between guard times CD.

A clock station used in an embodiment of the invention is shown in FIG.

In the clock station shown in FIG. 3, a received signal input through the input terminal 21 connected to the loop 8 is supplied to the latch circuit 14. The clock extraction circuit 13 extracts a clock from the received signal. The latch circuit 14 latches the received signal using the extracted clock, and its output is supplied to the latch circuit 15'. The latch circuit 15 is clock source 1
The silatch operation is performed using the clock of 6. Therefore, the latch circuit 15 sends out a signal in synchronization with the clock of the clock source 16. FIG. 4 shows an example of the configuration of a signal block used in the present invention. The signal block in Figure 4 is the preamble PR.
, start delimiter SD, access control AC, destination address DA, originating address SA.

The control circuit 12 of FIG. 3 has a period T and is composed of an information field INFO and an end delimiter ED. When the receiving circuit 11 detects the end delimiter ED of the passing signal block, it switches the switch 10 from the latch circuit 15 side to the selector 17 side, controls the selector 17, and controls the signal in the transmitting buffer 20 to be sent out. block(
In this case, the preamble Pl (trigger signal in this case) is output to the output terminal 22. If the receiving circuit 11 does not detect the preamble PR of the signal block from another station while the preamble PR, is being sent, the preamble PR is transmitted. and preamble PRI' to the signal block of the transmit buffer 20.
(The transmission is continuously transmitted. The above transmission control is based on the time T when the 241 circuit 18 gives the protection time Tg, (T, =T
o-Tg), and when the transmission right is acquired after the time T is indicated, the selector 17 is controlled and the clock signal output from the clock signal supply circuit 19 is supplied to the output terminal 22.

The type circuit 18 counts the clocks of the clock source 16 and is reset every cycle T0, and notifies the control circuit 12 of the time within the cycle. . This will continue until you are notified of the progress.

The control circuit 12 has a period T. When you know the progress of , selector 17
The signal block stored in the transmission buffer 20 (in this case, the first transmission signal block of the cycle is the synchronization signal 8YN) is sent to the output terminal 22 via the switch 10. Thereafter, normal transmission control is performed until the timer circuit 18 outputs time T. Since the transmission operation of the node station is performed based on the clock of the clock source 16, the signal block supplied from the output terminal 22 to the loop 8 and clock signals are all synchronized to the clock of clock source 16.

(Effects of the Invention) As stated above, according to the present invention, all node stages and clock stations stop communication during the protection time Tg, but during that time, the clock stations transmit clock signals to the node stages. Since each node station can extract the clock from this clock signal, it is possible to make the clock synchronization characteristics of the loop network more stable.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a loop-shaped network, FIG. 2 is a diagram showing the flow of signal blocks on a loop-shaped transmission path, and FIG. 3 is a diagram showing the configuration of a hundred clock stages in an embodiment of the present invention. The block diagram in FIG. 4 is a diagram showing an example of the configuration of a signal block used in this embodiment. In the figure, 1, 2, 3, 4, 5.6 are node stations, 7 is a clock station, 8 is a loop-shaped transmission line,
10 is a switch, 1] is a receiving circuit, 12 is a control circuit, 1
3 is a clock extraction circuit, 14°15 is a latch circuit, 16
is a clock source, 17 is a selector, 18 is a timer circuit, 1
9 is a clock signal supply circuit, and 20 is a transmission buffer. Ki 1 Figure Z cheer←−To −1−−sky

Claims (1)

[Claims] A clock station and a plurality of node stations are connected by a loop-shaped transmission line, and the clock station performs polling control within a certain period, and at the end of the period, the intermittent node stations for a predetermined period of time are A clock supply method for a loop network in which transmission control is stopped, wherein the clock stage supplies a clock signal to the loop transmission line during the hold time.