JPS6135037A - Transmission control system of loop network - Google Patents

Abstract

PURPOSE:To keep the code error produced on a transmission line within the period and to bring the state to the normal state from the next period by allowing a trigger station to interrupt the transmission line until the start time of the next prescribed period when the station detects a signal succeeding to a synchronizing signal circulated through the transmission line. CONSTITUTION:An output 4-1 of an access control section 4 of the trigger station TS20 keeps an active state until the synchronizing signal is returned throug through the transmission line 24 and when an LED detection section 2 detects the end delimiter of the own synchronizing signal, the control section 4 resets the output 4-1. Then a switch 1-1 is connected to the transmission line 24 and a signal succeeding to the synchronizing signal is bypassed to an adjacent node station NS. When the detection section 2 detects the end delimiter of the packet transmitted from each station NS and a loop supervisory section detects the idle state after passing of the end delimiter, an output of an AND gate 9 is activated. The control section 4 activates again the output 4-1, the switch 1 is connected to a selector 7 to allow the selector 7 to select a POL register 11 via an output 4-2 so as to transmit a polling signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention can be used in a loop network even when an error occurs in the transmission/reception control on the transmission path, such as when a code error occurs on the transmission path. The present invention relates to a transmission line control method that enables prompt and normal reception control.

(Conventional method) A communication method that realizes the integration of wideband services such as video communication and high-definition images in addition to the integration of voice communication and data communication. There is a loop network described in ``A study of high-speed synchronous packet looseness'' written in SB 83-107. In the loop network,
A high priority level is given to packets for large-capacity continuous communication such as audio/video synchronous communication and still image communication, and a medium priority level is given to packets that allow a certain amount of delay for data communication etc. - Give a low priority level and integrate these various communications.

This loop network constitutes a network as shown in FIG. 6(,). In the same figure, trigger station T820 transmits a synchronization signal (SYN) onto transmission line 24 at regular intervals, and node station N5
21, N822, and N823, a polling signal (POL) giving the respective priority levels is transmitted. Node stations N821, N822, and N523 are on transmission line 2.
Packets are sent and received via 4. These four stages are connected in a loop as shown in the figure by a transmission line 24. (In this specification, the trigger station is T8.-i and the node stage 100) is N.
8, and T8 and NS are collectively called the stage number. ) In this loop network, as shown in FIG.
Sends a synchronization signal (SYN) to When each NS receives the synchronization signal (8YN), it learns the start of a cycle, prepares to transmit the high priority level packet, and transmits the same packet after the synchronization signal (8YN) passes. For example, as shown in FIG. 6(a), N521 receives the synchronization signal (8YN) sent by Ta2O, waits for the same signal to pass, and then sends the synchronization signal (8YN) as shown in FIG. 6(b). The packet (
PKTI) is transmitted. Similarly, after receiving the synchronization signal (8YN), N822 also receives the synchronization signal (SYN) and P
Wait for KT 1 to pass, and then write the end delimiter (LE) of PKTI.
Immediately after passing D), PKT2 is transmitted. Also, N82
When there is no packet to be transmitted to N823, N823 only passes each of the above-mentioned signals and does not transmit any signals.

When the synchronization signal (8YN) transmitted by Ta2O goes around the transmission path 24 and returns, Ta2O transmits the synchronization signal (8YN).
) is removed from the transmission line 24, and further N521 and N8
After passing PKTI and PKT2 transmitted by No. 22, immediately after passing the end delimiter (LED) of PKT2, a polling signal (POLl) for starting the medium priority level communication is transmitted. Further, when the packet (PKTI) that it sent has made one round through the transmission path 24 and returns, N821 removes the same packet from the transmission path 24 as shown in FIG. 6(C). Thereafter, each station transmits in the same manner, but TS20I/'i and polling signals are repeatedly transmitted to the transmission line 24 for a period T in the order of decreasing priority level given by the polling signals, and then At the next cycle, a synchronization signal (8YN) is transmitted, and each N8
Activate high priority level communication again.

FIG. 7 is a diagram showing the flow of signals on the transmission line 24 when each station transmits signals according to the access method described above. As shown in the figure, the synchronization signal (8YN) sent by Ta2O is followed by PKTI and PKT2 (high priority level buckets sent by each 88), and after each of these packets, Ta2O sends a synchronization signal (8YN) to each N8. A polling signal (POLI) sent to initiate the transmission of medium priority level packets follows, and in the same way, this polling signal (POLI) is followed by each N8
medium priority level bucket) PKT3, PKT4, PKT
5, followed by a polling signal (POL 2 ) and a low priority level packet PKT6. In this way, the period T
is divided into priority levels by the synchronization signal (8YN) and polling signals (POLI and POL2) transmitted by Ta2O, making it possible to efficiently accommodate various types of communication.

(Problems with the Prior Art) In the loop network, when starting to transmit a packet, the transmission line 24 is temporarily disconnected, the signal within the own station is transmitted, and this signal goes around the transmission line 24. After waiting for this, the same signal is removed from the transmission line 24, and then the transmission line 24 is connected again. In this way, each station controls the opening and closing of the transmission line 24 during transmission. Therefore, if each stage erroneously opens or closes the transmission line 24,
If a transmitted packet is dropped at some stage before it reaches the incoming stage,
Alternatively, a failure may occur in which the packet is not removed at the originating station even though it has made one round on the transmission path 24, causing an abnormality in the access method of each station. For example, in the example of FIG. 6, if the end delimiter (LED) occurs in the middle of PKTl due to a code error, as shown by the broken line in FIG. The removal ends when the end delimiter (LED) caused by the code error is detected. Therefore, as shown in the same figure (d), PKT
PKT2 sent without removing part of I (RR8)
goes around the transmission line 24 and reaches the transmitting station Nε2
Even if it returns to 2, it will not be removed at the same station.

Thereafter, this abnormal state will continue in which each transmitting station removes a signal different from the packet it transmitted.

(Object of the present invention) The object of the present invention is to prevent errors caused by code errors on the transmission path.
To provide a transmission line control system that can quickly perform normal transmission and reception control even when a signal that is not removed even after going around the transmission line occurs and an abnormality occurs in the transmission and reception control of each station.

(Structure of the Invention) According to the present invention, in a loop network in which one trigger station and a plurality of node stations are connected to a transmission path, the trigger station transmits a synchronization signal to the network at regular intervals. In the transmission path control method, the trigger station and the node station start the next fixed period after a fixed time determined by the time required for a signal to go around the loop network (from the start time of the fixed period) has elapsed. A loop network control method is obtained, which is characterized in that the transmission path is disconnected until the start time of .

(Detailed Description of Configuration) A loop network transmission line control method according to the present invention will be described in detail with reference to the drawings. The Ta2Os that constitute the loop network transmit a synchronization signal (8YN) and a polling signal (POL), and the frame structure of the packets of these signals is shown in Fig. 2 (a) and (b).
Shown below. As shown in the figure, the synchronization signal (8YN) is created by adding a packet start delimiter (8D) to the beginning of the signal frame (8FSYN) indicating that this packet is a synchronization signal (SYN), and 8FSYN)
It is created by adding an end-of-packet delimiter (LED) to the rear of the packet. Similarly, a polling signal (POL) is created by adding each of the delimiters described above to a signal frame (8FPOL) indicating that this packet is a polling signal. Note that the 5FPOL includes a priority level to be notified to each N8.

Further, the frame structure of the packet transmitted by each NS is shown in FIG. 2(C). This bucket, signal frame (
s p') is the header section (HDR) that includes packet originating address/terminating address information and frame control information.
and a message section (INFO) that transmits communication contents. Similar to the previous example, a start delimiter (8D) and an end delimiter (IED or LED) are added to this signal frame (SF) to form a packet. There are two types of end delimiters added to packets transmitted by each NS, as described below. That is, each NS
When transmitting multiple packets in succession as shown in the figure, an end delimiter (L) is added to the final packet.
In addition to ED), there is an intermediate end delimiter (IED) that is added to intermediate packets. Figure 3 shows that a certain NS has 2
In this example, NS packets are continuously transmitted as one signal block (8B).
, and the end delimiter (LED) is added to the second packet before transmission. That is, Ta2O
When any station in each NS finishes transmitting, it transmits the end delimiter (LBD) and ends its transmission.

Therefore, after each station finishes transmitting, it
4 - The end delimiter (
The LED) can identify the signal indicating the end of the signal block (SB) transmitted by the self, and the end delimiter (LED) detects the removal of the signal block (SB) transmitted by the self after the end of transmission. Just do it until it's done.

In the present invention, when signals that are not removed even after going around the transmission path 24 occur due to the code error 9 on the transmission path 24 described above, the Ta2O is provided with a period T in order to remove these signals. The transmission line 24 is disconnected for a certain period of time before the start of the synchronization signal (8YN), and after the transmission line 24 is in a no-signal state, the transmission of the synchronization signal (8YN) is started.

(Example) FIG. 1 is a diagram showing the configuration of the T820 according to the present invention, and FIG. 5 is a diagram showing the configuration of the N521, N822, and N523. Control of signal transmission and reception will be explained using FIGS. 1 and 5.

First, Ta2O transmission control will be explained.

In Ta2O shown in FIG. 1, the signal on the transmission line 24 is bypassed to the inscribed N521 via the switch section 1 when T82σ is not transmitted, and the end delimiter (LED) of the packet is detected. A loop that monitors the states on the LED detector 2 and the transmission path 24, receives the end delimiter (LED) detection output of the LED detector 2, and detects the idle state of the transmission path 24 after passing the end delimiter (LED). It is input to the monitoring section 3. The access control unit 4 connects the switch 1-1 of the switch unit 1 to the output terminal of the selector 7 when transmitting the synchronization signal (syN) and the polling signal (POL) on the transmission line 24,
Controls transmission of the signal. The counter 5 manages the transmission period T of the synchronization signal (SYN), and this counter 5
The output is made active every cycle T, and the access control unit 4 is instructed to transmit the synchronization signal (SYN), and the timer 6 is initialized. This timer 6 notifies the access control unit 4 of the time when transmission is possible, and as shown in FIG.
After t1 time has elapsed from the start of period T, the output is set to inactive state and the access control unit 4 is notified that transmission is possible. to notify you to stop sending. In the SYN register 10 and POL register 11,
The synchronization signal (SY
N) and a polling signal (POI, ) are stored, and one of the signals is selected via the selector 7 by the output 4-2 of the access control unit 4. Although not shown in FIG. 1, the POL registers 11 are provided with the number of priority levels required in the loop network, and the selection of these is also performed by the access control section 4.

When the access control unit 4 learns that the output of the counter 5 becomes active and the start of period T is detected, the output 4-
1 to the active state and connect the switch 1-1 of the switch unit 1 to the output terminal of the selector 7,
The selector 7 is instructed to select the 8YN register 1o via the output 4-2, and the synchronization signal (8YN)
Start sending.

The output 4-1 of the access control section 4 remains active after the start of transmission of the synchronization signal (SYN) until the signal returns after going around the transmission path 24. When the end delimiter (LED) of the transmitted synchronization signal (8YN) is detected, the output of the AND gate 8 becomes active, and the access control unit 4 receives this and outputs the intermediate output 4- Reset 1.

When the output 4-1 of the access control unit 4 is reset and becomes inactive, the switch 1-1 of the switch unit 1 is connected to the transmission line 24 side, and the synchronization signal (sy
The signal following N) is bypassed to momentary contact N521.

According to the specific example of FIG. 6 explained earlier, the synchronization signal (8Y
After transmitting the synchronization signal (SYN) until the synchronization signal (SYN) goes around the transmission path 24, the switch 1-1 of the switch unit 1
The transmission line 24 is opened using the synchronization signal (S
When the end delimiter (LED) of YN) goes around the transmission path 24 and is detected at the LED detection section i in the Ta2O shown in FIG. and the signal following the synchronization signal (SYN), that is, PKT, as shown in FIG. 6(c).
l and PK'l'2 are bypassed to N821. At this time, the output 4-1 of the access control unit 4 in Ta2O is in an inactive state as described above, but the LED detection unit 2 detects the end delimiter (LaD) of the packet transmitted by each N8. , and also the IBD detection unit 2
When the loop monitoring unit 3 that receives the end delimiter (LBD) detection output detects the idle state of the transmission line 24 after passing the end delimiter (LBD), the output of the AND gate 9 in Ta2O becomes active. become a state. Upon receiving this, the access control section 4 makes the output 4-1 active again, and switches the switch 1-1 to the selector 7.
It instructs the selector 7 to select the POL register 11 via the output 4-2, and transmits a polling signal (POL). That is, when the access control unit 4 receives an instruction to start the period T from the counter 5, it transmits a synchronization signal (SYN), and thereafter transmits a polling signal (POL).

In the specific example shown in FIG. 6, Ta2O detects the end delimiter (LED) of the packet when it passes through PKT2, and furthermore, immediately after the packet passes, the transmission line 24 is in a no-signal state.
That is, when detecting an idle state, a polling signal (POL 1 ) is transmitted.

Further, within the period T, Ta2O repeatedly transmits a polling signal (POL) as long as the output of the timer 6 is in an active state. Further, according to the present invention, when the timer 6 detects the passage of time t1 after the start of the period T and makes the output of the timer 6 inactive, the access control section 4 receives this and starts the counter. 5 to know the start of the next cycle (T-z
1), the output 4-1 of the section is activated, the switch 1-1 of the switch section 1 is connected to the output terminal of the selector 7, and the transmission line 24 is disconnected.

However, at this time, Ta2O does not transmit any signal.

By providing Ta2O with a time during which the transmission line 24 is disconnected, an end delimiter (LFiD) is inserted in the middle of a packet to prevent code errors on the transmission line 24 from occurring as described above. Even if a signal is generated that is not removed even after going around the transmission path 24 and an abnormality occurs in the reception control, Ta2
At O, the signal on the transmission line 24 is wiped out during the time (T-tl) that the same station disconnects the transmission line 24, and by the time the next cycle begins, the transmission line 24 is in a no-signal state. Therefore, the normal state can be restored from the next cycle T.

In order for Ta2O to remove all the signals on the transmission line 24 during the time (T-tl) that the transmission line 24 is disconnected as described above, the transmission line must be removed at the time T51j20 disconnects the transmission line 24. The signal on 24 reaches T within (T-tl) time.
Since it is sufficient to reach a2O, the set value t1 of the timer 6 is determined so that the value of (T-1l) is larger than the one-round delay time of the transmission line 24.

Next, the configuration within each NS and packet transmission/reception control will be described. In N8 shown in FIG. 5, the signal on the transmission line 24 is bypassed to the adjacent NS via the switch unit 31 when the NS is not transmitting, and the LED detecting the end delimiter (LED) of the packet A loop monitoring unit 33 that monitors the states on the detection unit 32 and the transmission path 24, receives the end delimiter (IID) detection output of the LED detection unit 32, and detects the idle state of the transmission path 24 after passing through the end delimiter (LED). , a SYN detection unit 35 that detects the synchronization signal (8YN) transmitted by the TS 20, and a priority control unit 44 that receives the polling signal (poL) and decodes the priority level to be transmitted.

The received signal is transferred to the terminal accommodated in its own NS after address matching is detected in the reception control unit 46. The transmission control unit 46 follows the transmission request from the terminal, accumulates the data to be transmitted in the transmission zipper 40 via the output 45-1, and sends the transmission request to the access control unit 34 via the output 45-2. and output it.

The access control unit 34 connects the priority control unit 44 to the transmission path 24.
When the priority level of the signal to be transmitted is equal to or higher than the priority level on the transmission path 24, the priority level of the signal to be transmitted is equal to or higher than the priority level of the transmission request output from the transmission control unit 45. Prepare for sending. The output 34-1 of the access control unit 34 is in an inactive state when not transmitting, and at this time the output 34-1 of the access control unit 34 is in an inactive state.
The switch 31-1 is connected to the transmission line 24.

When starting transmission after comparing the priority levels, the LE
The packet end delimiter (LED
), and when the loop monitoring unit 33, which receives the end delimiter (LED) detection output of the LED detection unit 32, detects the idle state of the transmission path 24 after passing the end delimiter (L, ED), AND When the output of the gate 39 becomes active, the access control section 34 receives this and starts transmission. That is, when the access control section 34 learns of the active state of the AND gate 39, the access control section 34 makes the output 34-1 of the section active, and connects the switch 31-1 of the switch section 31 to the output terminal of the selector 37. At the same time, it instructs the selector 37 to transmit the transmission data stored in the transmission buffer 40 via the output 34-2 of the same section.

If there is only one piece of data to send, the access control unit 34 adds an end delimiter (LED) to the same piece of data when finishing the transmission.
The selector 37 is instructed via the output 34-2 to add the The intermediate end delimiter (IBD) stored in the LED register 42 is added, and the end delimiter (LED) stored in the LED register 43 is added to the last transmission data to end the transmission. The selector 41 is instructed to do so via the output 34-3.

Furthermore, even when each NS finishes transmitting a signal, the output 34-1 of the access control unit remains unchanged until the packet transmitted by the NS makes one round on the transmission path 24, in the same way as the transmission control in TE01 described above. The switch 31-1 remains active, the switch 31-1 is connected to the output terminal of the selector 37, and the transmission line 24 is disconnected. When the self-transmitted packet goes around the transmission path 24 and the end delimiter (LED) of the packet is detected by the LED detection unit 32, the output of the AND gate 39 becomes active.
state, the access control unit 34 receives this and outputs the output 3.
4-1 to the inactive state,
The switch 31-1 of the switch unit 31 is connected to the transmission line 24 side.

When the SYN detection section 35 detects the early synchronization signal (8YN) on the transmission path 24, it initializes the timer 36. As shown in FIG. 4, this timer 36 keeps its output active for a certain period of time r2 (t2<tl) from the start of period T, and after 12 hours have elapsed from the start of period T, the output to be inactive. When the output of the timer 36 becomes inactive, the access control unit 34 temporarily suspends transmission even if it is in progress and initializes the switch unit 31;
The switch 31-1 is connected to the transmission line 24 side. Note that when the signal transmitted by each NS reaches T820, T
To prevent E20 from cutting the transmission line 24,
The value of time t2 is the setting value t1 of timer 6 in T820.
Set to a value smaller than the value obtained by subtracting the transmission path delay time from the value of . In this way, the switch 31- of each NS
1 is always connected to the transmission line 24 side before the start of period T.

(Effects of the Invention) As explained above, each node station (N8) constituting the loop network suspends transmission after time t2 has elapsed from the start of period T, and initializes the switch that opens and closes the transmission path. The transmission line is connected in a loop, and on the other hand, the trigger station (T8) disconnects the transmission line after time t1 has elapsed from the start of the period T, and removes all the signals on the transmission line within the period T. Because you can
Even if a code error that occurs during transmission causes a signal that is not removed even after one cycle of the transmission path, and an abnormality occurs in the transmission/reception control, the effect will be limited to the period T in which the code error occurred, The normal state can be restored from the next cycle.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the internal configuration of the trigger station TS20 constituting the loop network, and FIGS. 2(a) and (b)
) is a diagram showing the configuration of the synchronization signal (8YN) and polling signal (POL) transmitted by Ta2O, and (c) of the same diagram shows the configuration of each N8
FIG. 3 is a diagram showing the configuration of a signal block (8B) transmitted by each NS. FIG. 4 is a diagram showing the structure of the signal block (8B) transmitted by each NS. FIG. 4 shows the period T and the setting value t1 of the timer 6 shown in FIG. FIG. 5 is a diagram showing the configuration of each node station NS constituting the loop network, FIG.
(b), (C), and (a) are diagrams showing specific examples of the configuration of the loop network and packet transmission/reception control, and FIG. 7 is a diagram showing the flow of signals on the transmission line 24. In the figure, 1 is a switch section, 1-1 is a switch, 2 is an LED detection section, 3 is a loop monitoring section, 4 is an access control section, 4-1 and 4-2 are the outputs of the same section, 5 is a counter, and 6
is a timer, 7 is a selector, 8 and 9 are AND gates,
10 is an 8YN register, 11 is a POL register, 24 is a transmission line, 31 is a switch section, 31-1 is a switch, 32
is an LED detection section, 33 is a loop monitoring section, 34 is an access control section, 34-1, 34-2 and 34-3 are the outputs of the same section, 35 is a SYN detection section, 36 is a timer, 37 is a selector, 38 and 39 is an AND gate, 40 is a transmission buffer, 41 is a selector, 42 is an IED register, 43
45 is a transmission control section, 45-1 and 45-2 are outputs of the same section, and 46 is a reception control section. Figure 1 Bud 2 Figure 3 Figure 4 Figure 5 Figure 6 (α) (b) Figure 6 (C) Figure 7

Claims (1)

[Claims] In a loop network transmission line control method in which the trigger station transmits a synchronization signal to the network at regular intervals in a loop network in which one trigger station and a plurality of node stations are connected by a transmission line, the trigger station and the node station is characterized in that the transmission line is cut off after a fixed period of time determined by the time required for a signal to go around the loop network has elapsed from the start time of the certain period until the start time of the next certain period. Loop network control method.