JPS6377240A - Time slot assigning system - Google Patents

Abstract

PURPOSE:To allow the titled system to cope with the transmission of fluctuating data quantity by providing a flag bit representing whether or not a device is in use consecutively from a preceding time slot and a flag bit representing a return request of a time slot when the device is in use consecutively for other device to the time slot. CONSTITUTION:In case of the use extended to a time slot after a substantial assignment time slot, a flag C using the preceding time slot of a reception register 38 is set to '1'. Thus, a shift-in command is issued to a reception buffer 40 only when the flag C is consecutively logical '1' after the substantial assignment time slot and only when a data effective flag (BCF) is logical '1' to write a data in the register 38 into the buffer 40. Moreover, when a return request exists at the expansion of the time slot, a return request display flag R of the register 38 goes to logical '1'. Thus, a flag insertion circuit 54 commanded through a transmission permission circuit 46 brings the consecutive C flag to '0' and the R flag is made to '0'. Thus, the substantial time slot is to be returned.

Description

[Detailed Description of the Invention] [Summary] Time slot allocation used in a loop local area network system using a time division multiplexing method is a method in which time slots are allocated in advance in a time division manner according to transmission between each node. has the problem of not being able to cope with the amount of data that fluctuates temporarily.To solve this problem, each time slot has a flag bit that represents continuation from the previous time slot, and a flag bit that represents a request for return of the time slot during continued use. Each flag bit is provided, and the number of allocated time slots is increased or decreased according to an increase or decrease in the amount of data, thereby improving the transmission efficiency of the transmission line.

[Industrial application field]

The present invention relates to a time slot allocation method for a time division multiplexed loop local area network system.

In a local area network system used for data transmission over relatively short distances such as within a factory premises, a large number of applications exist within the network system. Each of these applications transmits different amounts of data over time, and sometimes there is no data to transmit at all.
There are times when the allocated time slot is significantly exceeded.

Therefore, if a time slot corresponding to the maximum amount of data to be transmitted is allocated between each application or between terminals, the capacity of the transmission path will increase significantly, and many unused time slots will occur, resulting in poor transmission efficiency. Undesirable. Therefore, it is necessary to improve transmission efficiency by managing the number of time slots allocated according to the amount of data to be transmitted without increasing the capacity of the transmission path.

[Conventional technology]

FIG. 7 shows the configuration of a conventional time division multiplexed loop local area network system.

In the figure, 10 to 15 are nodes having data communication and data processing functions, and 10a to 15a are nodes 10 to 15a.
15 is a corresponding terminal, and 16 is a transmission line connecting each node 10 to 15 in a loop.

In the network system with the above configuration, terminals 10a and 1
32. , the same time slot is assigned to terminals 11a and 14a. Then, from the terminal 10a to the terminal 13
When transmitting data to terminal a, use time slot (2), when transmitting data from terminal 11a to terminal 14a, use time slot (3), and when transmitting data from terminal 13a to terminal 10a, use time slot (4). , terminal 14a to terminal 1
When transmitting to 1a, time slots (5) are used, thereby eliminating interference between each time slot.

In addition, time slots (2) and (4), (3) and (
5) may use the same time slot.

[Problem that the invention seeks to solve]

In the conventional time division multiplexing method, only the number of occupied time slots allocated in advance can be transmitted, and the amount of data that changes over time (temporarily) cannot be handled. Also, if you allocate a time slot that corresponds to the maximum amount of data to be sent,
Since the capacity of the transmission path increases significantly and many unused time slots occur, there is a problem that the transmission efficiency deteriorates.

In addition, in the conventional C3MA/CD method and token passing method, one transmission basically occupies the transmission path, so when the number of terminals increases and the access to the transmission path increases, data collisions and occupancy of the transmission path may occur. However, there was a problem in that the transmission efficiency deteriorated rapidly, making it unsuitable for large-scale network systems.

The present invention was made in order to solve the above problems, and it is an object of the present invention to provide a time slot allocation method that can accommodate the transmission of variable amounts of data without increasing the capacity of the transmission line.

[Failure to solve the problem]

The time slot allocation method according to the present invention includes:
A flag bit (C flag bit) indicates whether the original time slot has been continuously used since the previous time slot, and a flag bit (R flag bit) indicates a request for return of the time slot when it is continuously used by another time slot. )
The number of time slots allocated is increased or decreased depending on the amount of data to be transmitted depending on whether these flag bits are set or not.

[For production]

In this invention, during normal operation of time slots, time slots TS-0, TS-1, TS-2, . . . are assigned to communication between nodes as shown in FIG. 1(a).
・C flag bit b1 and R flag bit b2 are 0
” is set.

When communicating between certain nodes, when the amount of data to be transmitted cannot be supported by the time slot TS-0 assigned to it, the time slot TS-0 is transmitted after the time slot 1-TS-0 as shown in Fig. 1(b). Depending on the amount of data, one or more unused time slots connected to TS-1 can be occupied and used, for example, time slot TS-1.
Timeslot TS-1 is ahead of timeslot TS-
C flag bit bl indicating that it is continuously used as 0
is set to “1”. This means that the transmission from one node to another node is extended by one time slot.

Furthermore, if a request to return the time slot TS-1 assigned to the original communication occurs during the expanded operation shown in FIG. 1(b) above, the time slot TS-1 will be returned as shown in FIG. The R flag bit b2 is set to "1" to request the return of time slot TS-1. The node that detects the R flag bit b2 immediately sets the flag bits bl and b2 to 0'' to respond to the return of the time slot.

In this way, it is possible to cope with the transmission of varying amounts of data without increasing the capacity of the transmission path.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a configuration diagram of a loop local area network system to which the time slot allocation method of the present invention is applied, in which nodes 20 to 25 have data communication and data processing functions, and nodes 20a to 25a have the functions of data communication and data processing. 20
Terminals corresponding to nodes 25 to 25 and 26 are transmission lines connecting each node 20 to 25 in a loop. - The overall configuration of the above system is the same as the conventional system, but differs in the following points.

That is, as shown in FIG. 3, the time slot allocated to communication between each node is a transmission data area and a BCF pin ("1") indicating the validity of the transmission data.
In addition to sending data valid, “0”: sending data invalid),
This is a C (Continue) flag bit that indicates that the time slot is being used continuously from the previous time slot (bl="l": The previous time slot is being used continuously. bl-"0": Forward ), and R (Release
) flag bit b2 (b2="1": return is requested; b2="0": return is not requested) is provided.

Next, the operation will be explained with reference to FIG.

In this embodiment, from terminal 20a to terminal 23a and terminal 2
1 time slot (2) each for transmission from terminal 1a to terminal 24a
, (3) is assigned.

FIG. 4(a) shows the usage status of time slots during normal operation, and when there is valid data to be transmitted from terminal 20a to terminal 23a and from terminal 21a to terminal 24a, each node 20.21 is assigned to this. Set BCF flag bit b3 of time slots (2) and (3) to 11''.

FIG. 4(b) shows the operational status when time slots are expanded. When the amount of data to be transmitted from the terminal 20a to the terminal 23a is large, the time slot (2) assigned to this is shown in (■). BC of next evening im slot (3)
Only when the F flag bit b3 is "θ", the C flag bit b1 is set to "1" in the node 20, and the terminal 20a is set to occupy two time slots as shown in (■).
from there to the terminal 23a connected to the node 23.

Note that the expanded state of the two time slots continues until a return request is made.

FIG. 4(c) shows the operating state at the time of requesting time slot return. During the operation of FIG. 4(b) above, the terminal 21a
Assume that data to be transmitted from the terminal 24a to the terminal 24a is generated. In this case, as shown in (3), the node 21 sets the R flag bit b2 of time slot (3) to "1" to request return of the time slot. The node 20 that detects R flag bit b2 = 11'' as shown in (2) immediately sets C flag bit bl and R flag bit b2 as shown in (2).
0'' to respond to the return of time slot (3).

In this way, according to the method of this embodiment, even if the time slot assigned to oneself is occupied by the previous time slot, when transmission data is generated, it will always be returned after going around the loop. Delays are hardly a problem, and the number of time slots can be increased or decreased to accommodate changes in the amount of data being transmitted.

FIG. 5 is a block diagram showing a specific circuit example of an arbitrary node section incorporating the time slot allocation method of the present invention.

In FIG. 5, the node section has a common section 30 and a plurality of line set sections 31. The common section 30 is a demultiplexer (DM) that receives transmission data from the previous node.
UX) 32 and a multiplexer (M
The demultiplexing device 32 is connected to the receiving bus 34, and the multiplexing device 33 is connected to the receiving bus 34 and the transmitting bus 36 via the selector 35. A transmission request signal is added from a transmission request bus 37.

The line sensor section 31 also includes a reception register 38.
A transmission register 39 and a reception buffer 40 and a transmission buffer 41 that temporarily store the contents of these registers 38 and 390.
and a receiver driver 42 for transmitting and receiving data between the receiving buffer 40 and the transmitting buffer 41 and the terminal 43, and further comprising a flag determination processing section 44 for processing the C flag, the R flag, and the BCF flag. There is.

FIG. 6 shows a specific example of the circuit configuration of the flag determination processing section.

In the figure, the data taken into the reception register 38 is taken into the reception buffer 40, and this data acquisition command is combined with the signal from the reception permission circuit 45 and the BCFC flag bit of the reception register 38.
It is given by the logical product of the AND gate 47 which requires two people. Further, the data in the transmission buffer 41 is output to the transmission register 39, and a data shift-out command for the transmission buffer 41 is given from the transmission permission circuit 46.

The reception permission circuit 45 and transmission permission circuit 46 have a C flag set in the reception register 38.

The bit data of the R flag and BCF flag is transferred to the inverter 48. The signals are selectively input to switches 51 to 53 via an AND gate 49 and an OR gate 50. Note that when each switch 51 to 53 is connected to the B contact point, it is the time slot expansion operation, and the A
When it is connected to the contact side, it is during normal operation.

Further, 54 is a flag insertion circuit for inserting flag bits representing expansion of the C flag bit, R flag bit, and BCFC flag bit time slot of the transmission register 39, a return request, and the presence or absence of transmission.
A command signal from the transmission permission circuit 46 and an output read command signal sent from the transmission buffer 41 are applied to the signal 4.

Next, the operation of the circuit configured as described above will be described.

First, in the reception operation, the original allocation is when time slots are used (normal operation).
flag, R flag is set to 0'', BCF flag =
Only when “1” (data is valid), a shift-in command is given to the reception buffer, which causes the reception register 38
The data therein is written into the receive buffer 41 and further sent to the terminal 43 through the receiver driver 42.

Further, when the original allocation is extended to use the time slots after the time slot, the C flag of the reception register 38 is set to "1". As a result, the "C flag bit" and the BCF
Only when the flag is "1", a shift-in command is given to the reception buffer 40 to write the data of the third day in the reception register into the reception buffer 40. In addition, even if the time slot originally assigned to you is used by someone else, BC
When the FC flag bit is set, no data is taken in.

Next, the operation during transmission will be described.

When using the original allocated time slot, the flag insertion circuit 54 sets the C flag and R flag of the transmission register 39 to "0" and sets the BCF flag to 61". As a result, the data in the transmission buffer 41 is It is read out to the transmission register 39 and further read out to the bus 36 of the common section 30.
．． It is transmitted to the next node through the selector 35 and multiplexer 33.

Further, if the originally allocated time slot can be extended, the flag insertion circuit 54 causes the C of the transmission register 39 to be expanded.
Set the flag to “1” and set the BCF flag to “0”.
” expands continuously until

Furthermore, if a return request is made when the time slot is extended and used, the R flag of the reception register 38 becomes "1".
Accordingly, the flag insertion circuit provided through the transmission permission circuit 46 sets the consecutive C flags to "0" and also sets the R flag to "0".

This means that the original time slot has been returned.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to cope with the transmission of a fluctuating amount of data without increasing the capacity of the transmission line with a relatively simple circuit.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the principle operation of the present invention, Fig. 2 is a configuration diagram of a loop local area network system using the time slot allocation/method of the present invention, and Fig. 3 is a diagram for explaining the time slot allocation method of the present invention. Configuration diagram, Figure 4 (a)
-(c) are operation explanatory diagrams of examples corresponding to FIGS. 1 and 2 of the present invention, FIG. 5 is a circuit diagram showing details of the node portion in which the time slot allocation method of the present invention is applied, and FIG. This figure is a specific circuit diagram of the flag determination processing section in FIG. 5, and FIG. 7 is a configuration diagram of a conventional time division multiplexing local area network system. 1 and 2, 20 to 25 are nodes, 20 a to 25 a are terminals, 26 is a transmission line, TS-0 to TS-2 are time slots, bl is a C flag bit, and b2 is an R flag bit , b3 is the BCFC flag bit. To 1 time slot --) - 19 time slot - Time slot spirit, folk Figure 3 node mantle νs'i,, 45g 3"; - Show 1 circuit diagram Figure 5 7 rack" profit Fig. 7 shows the origin of the system a of each country.

Claims (1)

[Claims] In a time division multiplexed loop local area network system, time slots (TS-0, TS-2,...
), a flag bit (b1) indicating whether the original time slot is in continuous use from the previous time slot;
A flag bit (b2
), and the number of allocated time slots can be increased or decreased according to fluctuations in the amount of data to be transmitted using these flag bits.