JPH02288750A - Inter-node time matching system - Google Patents

Abstract

PURPOSE:To match the time of each node without being affected by an inter- node packet transmission time and an in-node packet resident time by giving a sum between a timer value just before the transmission and the absolute time in the reception packet into a time matching packet and relaying the result to a succeeding node. CONSTITUTION:Every time various data packets sent from a master node 1 are received, a frame head detection circuit 4 gives a command of starting the count of a time with an elapsed time counter circuit 5. The received data packet is fetched in an internal program 7 through a reception circuit 8. A value of the sum of a time value T0 in the time matching packet received by its own node clock 6 and the elapsed time (t1) up to now in the elapsed time counter circuit 5 is set as a present time and a sum of the elapsed time (t2) up to now in the elapsed time counter circuit 5 and the time T0 is set to a time field of the packet for a node 3 as the present time and the data is sent to a transmission circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for accurately synchronizing the time of each node in an information network using a store-and-forward method such as packet exchange or message exchange.

[Conventional technology]

Conventionally, in this type of time adjustment method, there has been a method in which the delay time during packet relay is estimated in advance and the time delay is added to adjust the time.

[Problem to be solved by the invention]

The conventional time adjustment method described above has the disadvantage that accurate time adjustment cannot be performed due to fluctuations in the relay time of time adjustment packets due to increased traffic of data communication packets and differences in transmission time due to differences in communication speed between nodes. .

An object of the present invention is to provide an inter-node time adjustment method that solves the above problems.

[Means to solve the problem]

In order to achieve the above object, the present invention uses one time adjustment packet issued by one master node to adjust the time between nodes having data exchange or processing functions in an information network that communicates data using a store-and-forward method. It has a means for detecting the start of reception of one frame from one line in a method synchronized to the time of , and a timer means for counting the elapsed time from the time of detection.

If the received frame is a time adjustment packet, a first step of controlling the timer so that it is not restarted by subsequent frame reception, and an added value of the master node time in the time packet and the current value of the timer. The second step is to set the clock of the own node as the current time, and to relay the 1-time adjustment packet to the next node, the sum of the master node time in the time packet and the value of the current timer is set as the current time. The third step is to update the time value of the time adjustment packet and transmit it to the next node.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a connection configuration diagram of store-and-forward nodes according to the present invention. The present invention is an information network that communicates data using a store-and-convert method, and the time between nodes having data exchange or processing functions is shared by one node. The target is an inter-node time adjustment method that matches the time of one time adjustment packet issued by a master node. In FIG. 1, master node 1 transmits a time adjustment packet to node 2, and node 2, after synchronizing its own clock, transmits a time adjustment packet to node 3.

FIG. 2 is a configuration diagram showing the configuration of node 2 in the present invention. In FIG. 2, every time it receives various data packets transmitted from the master node 1, the frame head detection circuit 4 instructs the elapsed time counting circuit (timer) 5 to start counting time.

The received data packet is taken into the internal program 7 through the receiving circuit 8. When the received packet is a time adjustment packet, the program 7 performs control so that the elapsed time counting circuit 5 is not restarted by subsequent data communication. Time value T6 in the time adjustment packet
The value obtained by adding the elapsed time (tl) of the elapsed time counting circuit 5 up to the present time should be set as the current time. The node 3 sets the value obtained by adding the elapsed time (t2) of the time counting circuit 5 up to the present time to T as the current time in the time value field of the packet, and transmits the data to the transmitting circuit 9 (see 3 in FIG.
step 12).

Figure 4 shows the flow of time adjustment packets for each node.
In this figure, the time value sent from master node 1 to node 2 is T6, node 2 sets the time T, +t, to its own clock, and for node 3, the packet retention in node 2 A time adjustment packet is sent with the current value being T, +t2, which is the sum of time t3.

〔Effect of the invention〕

As explained above, the present invention provides a timer that is started from the reception start time of the time adjustment packet, sets the clock based on the sum of the timer value at the timing to set the time and the absolute time value in the received packet, and similarly When relaying a time adjustment packet to a node, the inter-node packet transmission time and It is possible to synchronize the time of each node without being affected by the intra-node packet residence time. Therefore, this method has the advantage that the times of all five nodes can be set to the same time using a normal packet communication line.

[Brief explanation of drawings]

FIG. 1 is a connection configuration diagram of store-and-forward nodes according to the present invention, and FIG. 2 is a configuration diagram showing the inter-node time adjustment method of the present invention.
FIG. 3 is a diagram showing the flow of the program shown in FIG. 2, and FIG. 4 is a diagram showing the flow of the inter-node time adjustment bucket. 1... Master node for time adjustment 2. 3... Node 4... Frame reception detection circuit 5... Elapsed time counting circuit (timer) 6...
Node internal clock 7...Time adjustment processing program

Claims (1)

[Claims] (1) In an information network that communicates data using the store-and-forward method, in a method in which the time between nodes having data exchange or processing functions is adjusted to the time of one time adjustment packet issued by one master node, It has a means for detecting the start of reception of one frame from the line, and a timer for counting the elapsed time from the time of detection, and when the received frame is a time adjustment packet, the timer means is used for the subsequent time adjustment packet. a first step of controlling to prevent rebooting due to frame reception; a second step of setting the sum of the master node time in the time packet and the current value of the timer as the current time in the own node's clock; In order to relay the time adjustment packet to the next node, the third node updates the time value of the time adjustment packet by setting the sum of the master node time in the time packet and the current value of the timer as the current time, and sends it to the next node. An inter-node time adjustment method characterized by performing steps.