JPS612446A - Centrarized supervisory bus type transmission system - Google Patents

Abstract

PURPOSE:To constitute simply and economically a multiple bus type network without providing a bus supervising means or a means for executing back off algorithm or the like in each node by using one network controller having a bus supervising means, a time supervising means and a means for executing a simple procedure. CONSTITUTION:A microcomputer CN receives information OP indicating whether a bus B is idle or not from a bus supervisory device, sends a timer start signal ST or a timer stop signal SP to a timer TM and receives a time up signal Tup from the timer TM. The bus supervisory device L supervises the existence of the idle status of the bus B and applies the bus supervisory information OP to the microcomputer CN as an interruption signal every change of the status. The time up signal Tup is generally transmitted to the microcomputer CN as an interruption signal. In addition, the microcomputer CN outputs a transmission command CMD to a transmitter TR to transmit a signal for applying a transmission right TN to a node N.

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] The present invention provides a system for transmitting data between a plurality of equal stations (also referred to as terminals or nodes) via a so-called bus-type common transmission line with open ends at both ends. The present invention relates to a hardware configuration and an access procedure for simplifying the system configuration in a multi-bus type transmission system (also referred to as a network) that performs n:n transmission and reception.

[Prior art and its problems]

In a bus-type network that normally performs n:n communication between nodes, each node has a means for monitoring whether the bus is free or not, and a means for executing retransmission procedures in the event of a collision of transmitted data. etc., making the hardware and software for each node quite complex. Particularly when connecting nodes that require relatively low-speed transmission, such a complicated configuration has the problem of lowering cost performance.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned problems in a bus-type network consisting of stations that communicate at relatively low speeds, to reduce complex network components, and to create an uninterrupted network consisting of simple hardware and procedures. The purpose is to provide

As a document related to this type of technology, there is a Japanese Patent Application No. 59-43167 by the present applicant, ``Multiple Bus Type Transmission System''.
There is.

[Key points of the invention]

The main point of the present invention is that in a transmission system (network) in which a plurality of stations (nodes) connected to a common bus-type transmission path with both ends open perform N:N communication with each other, the free space of the transmission path is A common transmission path vacancy determination means (such as a bus monitoring device) that determines whether the transmission path is available, and a common time measurement means (such as a timer) that determines that the vacancy time exceeds a predetermined time and outputs a time-up signal; A common transmission permission means (a microcomputer, If a transmitter (such as a transmitter, etc.) is installed in a network controller, etc., the station that is permitted to transmit by the transmission permission means will be able to send data frames, etc. to other stations as necessary to perform the transmission. That's what I did.

[Embodiments of the invention]

The present invention will be explained below with reference to FIGS. 1 to 6. In each figure, the same reference numerals indicate the same or corresponding parts. 1st
Figure 2 is a block diagram showing an example of the system configuration of the present invention, Figure 2 is a block diagram showing an example of the internal configuration of the network controller, and Figure 3 shows the transmission signals (also referred to as transmission frames) transmitted from each node and network controller. FIG. 4 is a flowchart illustrating the operation of the network controller, FIG. 5 is a flowchart illustrating the operation of the nodes, and FIG. 6 is a time chart illustrating the operation of the network as a whole.

FIG. 1 - Here, N (N1 to Nn) are n equal nodes, which are connected to the fifth
Communication is carried out according to the procedure shown in the figure. Further, C is a network controller connected to the bus Bt, which includes a bus monitoring device as a bus monitoring means to be described later and a timer as a time monitoring means, and executes the procedure shown in FIG. Note that T is a termination circuit provided at both ends of the bus B. Also here, node N(
Nl to Nn) may be anything that can execute the procedure shown in FIG. 5, such as a computer having a transmitter and a receiver, a microcomputer system, etc.

In the network controller CI shown in FIG. 2, L is a bus monitoring device, TM is a timer, TR is a transmitter, and ON is a microcomputer (hereinafter referred to as microcomputer) that executes the procedure shown in FIG.

The microcomputer CN receives information (referred to as bus monitoring information) OP as to whether or not bus B is vacant from the bus monitoring device.
It sends a timer start signal or a timer stop signal ST or SP to the timer TM, and receives a time-up signal Tup from the timer TM.

In this embodiment, the bus monitoring device monitors the availability of bus B, and provides bus monitoring information OP as an interrupt signal to the microcomputer CN whenever the status changes. The state of bus B may be constantly read from .

Further, the time-up signal 'l'up is generally transmitted to the microcomputer CN+ by means of an interrupt signal.

The microcomputer CN also sends a transmission command C to the transmitter TR.
MD is sent out, and a signal (transmission ◆ frame 1
0) is sent.

Taking into account FIG. 3, 10 is the transmission right frame,
This is a signal in which the system controller C designates the node Ns by its node address A and grants the transmission right TN.

11 to 13 are each part that constitutes this transmission right frame 10. 11 is a signal indicating the start of the transmission frame (header H)
12 is a node address part that stores the node address A, 13 is a signal corresponding to a command or its response (in this case, only the transmission right TN corresponding to the songwriter) Command to store /
This is the response part.

20.30 is an example of a signal (also called a node communication frame) when nodes N communicate with each other, and when this signal calls 20 as a command or response data frame or all at once depending on either a command or response. is called a command/response data frame. Similarly 3
0 + is often referred to as a command or response frame or command/response frame. Note 21.3
1 is a header section similar to the above, 22.32 is a node address section that stores the address A of the other node N that receives the signal, and 23.33 is a command/response section, in which the signal is a command or a response. The command CM or the response R is stored depending on which one it corresponds to. Further, 24 is a data section in which data DATA accompanying the signal is stored.

Note that each of the frames 10, 20, and 30 described above is collectively referred to as a received frame as described above.

Next, the operation of this system will be explained.

(1) At the beginning of the operation of the network controller, see Figure 2.
Referring to FIG. 3, the operation of network controller C will be explained from the number in FIG. 4. In step 101, the microcomputer ON receives information from the bus monitoring device via the bus monitoring information OP.
It is checked whether bus B is free or not. If it is free (branch Y), timer TMs is started at step 102 by sending a timer start signal ST, and a predetermined time (timer If it is determined that bus B has remained vacant for a period of time (referred to as time) (step 103A).

103B, each branch Y), assuming that there is no communication between node N, and specifying the next i-numbered node address A determined by a predetermined method in step 104, that node - Transmit a frame (transmission right frame 10) giving the transmission right TN. Here, as described later, the timer time is used for command transmission in communication between arbitrary nodes N.

Command data frame 20. or command frame 3
0 until the network controller C detects the transmission of a response (response data frame 20 or response frame 30).

If bus B is no longer free before the timer time is reached, step 103A follows branch N to step 1.
At step 05, the timer TM is stopped and the process returns to step 1011. As described above, in step 104, the right-to-send frame 1 is
After transmitting 0, the node address A is updated in step 106, and when it is determined in step 107A that the allocation of transmission rights to all nodes has been completed (branch Y), step 10
At 7B, the 7=nido address is returned to the beginning and the process returns to step 101. If not (step 107A branch N), the process directly returns to step 101.

(2) Operation of Node Next The operation of node N will be explained using FIG. 5 while referring to FIG. 3. The flowchart in FIG. 5 focuses on the case where communication is started by addressing (polling) network controller C, so it is possible to If so, step 20
They are collectively represented as 6.

In step 201, when a transmission frame (10, 20 or 30) as shown in FIG. It is checked whether the node address A in the transmitted frame is for the own node. If it is not for the own node, ignore it (branch N) and return to step 201. If it is for the own node (branch Y).
, in step 203, the command/response part (13°2
3 or 33) is the transmission right TN, and if the transmission right TN is obtained (branch Y), step 204
If there is data to be sent (branch Y), repeat steps 205'' and 204 until there is no more data to send, then send 1; if there is no data to be sent (branch N to Stellaf 204),
Ignore it and return to step 2011. If the command/response part does not give the transmission right TN (therefore, command CM or response R) (step 2o3° branch N), proceed to step 206+, perform processing according to the command or response, and proceed to step 2011. Go back and repeat once.

Although the operations of the network controller C and the node N have been explained separately above, the operation of the network as a whole will be explained with reference to FIG. In the same figure, general 1 node number M
For the sake of simplicity, the node N will be written as a node (M), and the address of the node (M) will be written as AM. Figure 6 shows the data frame from node (1) to node (M) + this data frame, that is, data DA'I'A 1 to DA
TAK (however, data frames other than DATA 1 and tl' command data frame 20-1 are not shown) is transmitted, and the upper diagram (a) shows the signal on bus B (transmission frame 10°20 or 30), the lower diagram (b) represents a signal related to the timer in the network controller C (timer start/stop signal ST/SF or time-up signal Tup). Also, from network controller C, frame N frame (1), frame (
2) - Transmitted transmission right frame 10-1.10-2
The headquarters are attached. Sakisuke represents time.

First, the network controller C transmits a transmission right frame 10-1 to the node (1) to grant the transmission right TN, and at the same time, it starts by giving a timer start signal 8T1 to the timer TM+ and starts monitoring its time-up. A command data frame 20-1 is sent from the node (1) that has been given the next transmission right to the node (M)I, and the network controller C detects this and sends the timer TM+timer stop signal SP1. However, when the end of the command data frame A20-1 is detected, a timer start signal 8T2 is issued to start the timer TM. From the next node (M) to the node (
1) When the coma response frame 30-1 is sent, the network controller C issues a timer stop signal SP2 to stop the timer TM, and at the end of the response frame 30-1, starts the timer TM again with a timer start signal ST3. let The same process is repeated until the final command data frame 2O-K (not shown) is sent to the attached response frame 30-.
The timer is started again (timer start signal 5
T(K+2)), since both the command data frame and the response frame are no longer transmitted, the timer TM times up, and by giving the time-up signal Tup to the microcontroller CNf, the network controller C
transmits the transmission right frame 10-2 to the node (2) at the next address (number 2), giving it the transmission right.

Note that if there is a significant difference in the frequency Q of transmission requests made by nodes 1, or if there is a difference in the urgency of transmission,
The frequency with which the transmission right TN is granted may be differentiated; in this case, the probability of the network controller C granting the transmission right is the node where transmission requests occur more often or the nodes that require urgent transmission. make it higher.

〔Effect of the invention〕

It is clear from the above description that the present invention uses one network controller having bus monitoring means, time monitoring means and means for carrying out simple procedures. .

A multi-bus network can be easily and inexpensively constructed without providing a bus monitoring means or a means for executing a back-off algorithm (procedure for resuming transmission in the event of a collision). Furthermore, since the network controller only needs to know the address of each node, it is extremely easy to change the settings as the number of nodes increases or decreases.

However, since the present invention is a system in which the network controller grants transmission rights to each node through polling, it is suitable for systems that require relatively low-speed transmission. In addition, we have eliminated the need for a means to detect collisions for each node, but if during communication between two nodes, another mate who does not have the right to send a message accidentally sends a message, the CRC (CRC)
This can be checked using a cyclic redundancy code (cyclic redundancy code), etc.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an example of the system configuration of the present invention;
FIG. 2 is a block diagram showing an example of the internal configuration of the network controller, and FIG. 3 is a diagram showing the configuration of signals transmitted from each station and the network controller.
FIG. 4 is a flowchart explaining the operation of the network controller, FIG. 5 is a flowchart explaining the operation of the nodes, and FIG. 6 is a time chart explaining the operation of the system as a whole. N (N1~Nn)...Station (node), C...
...Network controller, B...Bus, T...Terminal circuit, CN...Microcomputer, L...Bus monitoring device, TR ...Transmitter, TM ...Timer.

Claims (1)

[Claims] 1) In a transmission system in which multiple stations connected to a common transmission line with both ends open communicate with each other N:N,
a common transmission line vacancy determining means for determining whether or not the transmission line is vacant; a common clocking means for determining that the vacancy time exceeds a predetermined time and outputting a time-up signal; and a common transmission permission means for specifying the stations one by one in a predetermined order each time the output of the signal is determined, and permitting the station to transmit, and the transmission permission means A centrally monitored bus-type transmission system in which stations that are permitted to transmit transmit to other stations as necessary.