JP3228573B2 - Transmission request control device in LAN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local area network (hereinafter, referred to as "LAN") for exchanging information between a plurality of transmission control stations connected to a common transmission line. The present invention relates to a transmission request control device for performing transmission path allocation control according to the degree of urgency of a transmission.

[0002]

2. Description of the Related Art In recent years, in factory automation, intelligent devices such as computers, programmable controllers, and digital instrumentation controllers have been networked, and real-time processing control data and monitoring data are not required. There is a tendency to build a continuous process control system in which production information and the like are loaded on the same LAN.

[0003] Under such circumstances, as a control LAN system that satisfies real-time requirements, a token that enables each transmission control station to acquire a transmission right and transmit data within a predetermined time that can be predicted. A passing LAN system has been standardized.

[0004] As token passing LAN systems, there are a bus LAN according to ISO 88024 or IEEE 802.4 standard and a ring LAN according to ISO 9314 or ANSI X3T9.5 standard.

In these token passing systems, a transmission right is sequentially given to each node by passing a frame called a token between the nodes. When each node receives the token, it transmits data within a preset time. By doing so, each node can calculate the maximum time that it has to wait before transmitting its own data from the total number of nodes and the set time of each node, and transmit data in order. Therefore, definite transmission path access is possible.

In this type of LAN system, four types of access classes are usually set for data to be transmitted, and transmission path access priority processing according to the access class is performed. With these four types of access classes, the highest priority is 6, and the priority is sequentially reduced to 4, 2, 0, and four queues can be created for data to be transmitted. The transmission of the access class 6 is restricted within the specified token holding time, and for the access classes 4, 2, and 0, it is necessary for the token to circulate in the logical ring by the timer managed by each access class. The time is measured, and data transmission of each access class is performed until the measured value reaches the target token rotation time value given to each access class.

[0007] When each node receives the token, the access class 6 transmits data until the specified token holding time is reached or until there is no more data in the queue of the access class 6, and then the lower access class. Pass the token to. The lower access class receiving the token performs data transmission until the timer (time) of the access class reaches the target token circulation time or until there is no more data in the queue of the access class. If the timer value exceeds the target token rotation time, the data of the access class cannot be transmitted, and the token is passed to a lower access class. In the case of the lowest access class, a token is passed to the succeeding node.

[0008]

As described above, as described above, ISO 88
024 (IEEE 802.4) standard or ISO 9314 (ANSIX
In the token passing system such as the 3T9.5) standard, transmission request control is managed by a timer of each transmission control station. Even if the other station has more urgent data than the data of the access class that currently holds the token, the timer value of its own station has room for data transmission,
When data exists in the queue, data transmission is continued until the timer value reaches a set value or until there is no more data in the queue. Therefore, a situation may occur in which data of another station with high urgency is not transmitted. That is, from the viewpoint of the entire system, even if data with a high degree of urgency exists, if data transmission requests with a lower degree of urgency overlap at each transmission control station, data with a higher degree of urgency is not necessarily transmitted. It is not limited.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a transmission request control device capable of achieving transmission path allocation control according to the urgency of data in the token passing system, as viewed from the whole system. .

[0010]

According to the present invention, there is provided a transmission request control method in a local area network for exchanging information between a plurality of transmission control stations connected to a common transmission line. One transmission control station transmits a synchronization frame for system synchronization in synchronization with a fixed time, and releases a token within a predetermined time upon receiving a token frame indicating transfer of data transmission right, and The transmission control station includes a media control unit MAC having a mode M1 capable of transmitting a required number of data frames when a token frame is received, a management list L1 for managing a data transmission allocation request of its own station, and a data list of another station. The data is provided with a management list L2 for managing the transmission assignment request and an identifier I1 indicating the urgency of the data when there is a data transmission request. In turn sends the data request queue Q1
And a data frame to be transmitted when a token frame is received next from the management lists L1 and L2 when a synchronous signal interrupt occurs at a fixed time.
Means for linking to a transmission queue Q2 to which data frames other than 1 are linked, and a data transmission assignment request frame not including these data frames for which transmission has been determined is created based on the transmission request queue Q1, and data corresponding to mode M1 is created. Means for linking as a broadcast frame to a transmission queue Q3 to be linked, means for transmitting a frame in mode M1 including a data transmission allocation request frame when a token frame is received, and thereafter transmitting all data frames for which transmission has been determined, Means for deleting the transmitted data frame from the transmission request queue Q1 when the frame transmission is completed, creating a management list L1 corresponding to the data frame for which the allocation request has been made by the data transmission allocation request frame, and transmitting from the other transmission control station. Data transmission allocation request frame Crowded taken it to the internal management list L
2 and a means for monitoring a data frame transmitted from each station and deleting transmission request information from the management list L2.

[0011]

In the transmission request control device of the present invention, when each transmission control station broadcasts a data transmission request allocation frame in mode M1, the transmission control station (master station) transmits a synchronization frame in synchronization with a fixed time. In, when a token frame is received, and when the other transmission control stations receive a synchronization frame, the data transmission allocation request including the management list L1 and the management list L2 of each transmission control station is the same for each transmission control station. is there. That is, since each transmission control station knows the transmission assignment request of the entire system, and each transmission control station knows the common time between the stations, the data registered in the management list L1 is used as the whole system. It can be determined whether the urgency is high.

Incidentally, the remaining time T1 excluding the mode M1 time of the entire system and the token circulation time from the transmission cycle of the system synchronization frame can be calculated at the time of system configuration. Each transmission control station selects a data frame that can be transmitted within the time T1 in descending order of urgency from the data identifiers I1 registered in the management lists L1 and L2 when the synchronization signal is detected. The data frame selected here is the same for each transmission control station. If the transmission control station has its own data frame in it, the transmission control station transmits the data frame of mode M1 at the time of receiving the token, transmits all the data frames of the selected own station, and then transmits the token. Give it to the bureau.

In this way, each transmission control station can preferentially transmit data with a high degree of urgency as the whole system.

[0014]

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

First, a configuration example of a transmission system to which the present invention is applied will be described with reference to FIG. .., 1 (N−) on the common transmission line 1.
2), 1 (N-1) and 1N are connected. The figure shows N
Of the transmission control stations, 11, 12, 13, 1 (N-
2), 1 (N-1), 1N only are shown.

Each transmission control station basically has the same internal configuration. As shown in FIG. 4, the transmission control stations are mainly composed of a control microprocessor (MPU) 27. The MPU 27 controls the token passing transmission control circuit 22
And a common transmission line 1 via a transmission / reception circuit 21. The token passing transmission control circuit 22 includes a transmission queue Q3 to which a frame of mode M1 is linked and a transmission queue Q2 to which a frame other than mode M1 is linked.
It has a function to release the token after transmitting all 2 data frames. The MPU 27 includes a transmission / reception buffer RAM 23 for storing transmission / reception frames, a transmission / reception control RAM 24, a transmission request interface 25 for receiving a data transmission request from a connected host device, and a time measurement for measuring and managing the time or time common to the systems. M storing the processing programs of the circuit 26 and the MPU 27
A PU ROM 28 and an MPU RAM 29 for storing data necessary for processing of the MPU 27 are connected.
The master station among the plurality of transmission control stations has a synchronization control circuit 30 for performing synchronization control of each transmission control station.

In the transmission request queue Q1 of each transmission control station,
In response to the data transmission request interrupt signal SIG1 received from the host via the transmission request interface 25, the transmission request data messages 40 as shown in FIG. The deadline indicates the final time at which the data has to be transmitted, and is represented and managed by the time measurement circuit 26 as a time or time common to the system. Transmission request data message 40
Is composed of eight blocks 41 to 48 here. The first block 41 includes a transmission request data message N having the next highest urgency after the data, that is, having a deadline next to the data. MSG Stores the address of the LA. The transmission request data message having the latest deadline in the transmission request queue Q1 is added with an identifier IL indicating that it is the last data message. P MSG Second block 4 labeled LA
2 represents the address of a data message that is one more urgent than the data. That is, the data message is the data message N MSG N of the data message linked by LA MSG Stores the address of the LA. If the data message has the earliest deadline, an identifier IT indicating that it is the first data message is added to the label of the second block 42. RMSG The third block 43 labeled LA is a block used to link only the data registered in the data transmission allocation request frame transmitted when the token was received last time. In the transmission request data message registered in the data transmission assignment request frame, the address of the data message having the next deadline is stored, and the registered data having the latest deadline has the identifier IL. Is added. MSG
A fourth block 44, labeled D, stores the deadline of the data message, A fifth block 45, labeled L, stores the frame length of the data message, a sixth block 46 stores the address of the transmission request data from the host, and a seventh block 47 stores the data message N MSG This is a block for storing the LA header address. The eighth block 48 represents transmission request data of the host.

The management of data messages linked to the transmission request queue Q1 in the order of the deadline is performed by a transmission request queue Q1 management table 50 as shown in FIG. The block 51 labeled FMSG is the data message N having the earliest deadline among the data messages linked to the transmission request queue Q1. MSG
Stores the address of the LA and stores the FMSG Block 52 labeled D stores the deadline. L
The block 53 labeled MSG is the transmission request queue Q
1, the address of the data message having the latest deadline among the data messages linked to
MSG Block 54 labeled D stores the deadline. That is, the management table 50 indicates the first data message and the last data message linked to the transmission request queue Q1, and the MPU 27
In FIG. 4, the transmission request data message linked to the transmission request queue Q1 can be known from the management table 50 and the address of each data message.

FIG. 1 shows a data transmission request acceptance processing flow.
Sends the data transmission request interrupt signal SIG1 from the host to the MPU.
27 shows a processing flow when detection is performed. M
The PU 27 stores the transmission request data in the transmission request queue Q1.
Link in deadline order. First, MPU
27 is transmission request data received by the interrupt signal SIG1
Deadline MSG of message MG1 D (FIG. 5)
Deadline FMSG D (FIG. 6) and MSG
If the deadline indicated by D is earlier,
Even if this transmission control station has the most urgent data
If the data message address of the data message MG1 is
SU MSG Identifier IT to LA, data message
Address N MSG Data message FMSG to LA
And stores the address indicated by FMSG.
Message P MSG Data message MG1 to LA
N MSG Enter the address of LA in the data message F
The MSG contains the N of the data message MG1. MSG LA's
Enter the address as the deadline FMSG Data message on D
MG1 MSG By storing the value of D,
Of the transmission request queue Q1 of the message MG1
(Steps S1, S2, S3). FMSG Indicated by D
If the deadline is earlier, the MPU 27
Deadline MSG of Sage MG1 D and LMSG D
And MSG Deadline indicated by D is slower
If it is, that is, the most urgent level in this transmission control station
Is low, the P of the data message MG1
MSG LA is the value of LMSG (FIG. 6),
N MSG In LA, N of data message MG1 M
SG Stores the address of the LA and stores the data message in the LMSG.
N of Sage MG1 MSG Enter the address of LA in LMS
G MSG on D The value of D is stored and the data message M
N of G1 MSG To store the identifier IL in LA
From the transmission request queue Q1.
The tail is set (steps S4, S5, S6). Data message
Deadline MSG of Sage MG1 D is FMSG D
And LMSG If it is between D and FMSG
N of the first data message in the transmission request queue Q1 M
SG From LA, the next most urgent data message
Know the address and deadline of the data message
MSG MSG of D and MG1 D and compare the data
MSG of Message MG1 Deadline indicated by D
Is late, N MSG From LA, the next most urgent data
Knows the address of the data message and
The Deadline MSG MSG of D and MG1 With D
Compare the deadline MSG of the data message MG1
Data message with deadline slower than D
Repeat until it appears. Such a data message MG
2 is found, the address of the data message MG1 is
SU MSG LA is the address of data message MG2
SU MSG The value of LA is used as the value of data message MG2.
P MSG Data message N indicated by LA MS
G LA is the P of the data message MG2. MSG LA's
Address and the N of the data message MG1 MSG
In the address of LA, P of MG2 MSG LA to MG1
N MSG By setting the LA address,
Data message MG1 to the transmission request queue Q1.
(Step S7). Thus, the transmission request queue Q1
, The data messages are linked in order of urgency.
The deadline MSG Multiple data with the same D
If there is data, the earlier the transmission request is, the higher the urgency
Treat as something.

Each transmission control station requires its own data transmission quota.
Request management list L1. Fig. 7 shows the management list.
1 shows an example of the configuration of L1. Each transmission control station has a token
The deadline is always reported when the
The strike (L1) 60 is the latest data transmission allocation request frame.
Registered in the data, that is, the transmission
Manage request data. The management list (L1) 60
Data transmission allocation request sent when receiving a token frame
The earliest deadline among the data registered in the frame
Data message N with in MSG LA address
RFMSG block 61 for storing the data
RFMSG to store the data line D block 62, same
Data registered in the same data transmission quota request frame.
N of the data message with the slowest deadline
MSG RLMSG block for storing LA address
RLMS storing the deadline of the data 63
G It is constituted by a D block 64. Data sender assignment
Each data registered in the request frame is a data message.
The RMSG LA deadline early in the deadline
Clicked. RMSG LA is the next most urgent
High data N MSG Stores the address of the LA. tube
The management list L1 stores the top and bottom of these linked data.
The MPU 27 indicates the end of the management list L1.
RMSG of each data Transmission notified to other stations by LA
Request data can be known. The MPU 27
Data is transmitted to the transmission request queue Q2 by the frame transmission processing.
When linked, RLMSG contains the last data N
MSG The address of the LA is stored and RLMSG D
Stores an identifier TX indicating a transmission decision.

Further, each transmission control station has a data transmission assignment request management list L2 of another station. FIG. 8 shows a configuration example of the management list L2. The management list (L2) 70 manages a data transmission assignment request of another transmission control station. The management list L2 includes a transmission control station address 71 indicating which transmission control station is the transmission request data, a total number of records 72 indicating a size other than the management list L2, and a transmission control station indicated by the most recently received transmission control station address. The number of transmission request data 73 represents the number of data registered in the data transmission allocation request frame from, and a record 74 as shown in FIG. There are as many records as indicated by the total number of records, arranged in the order of deadline. Record is RMSG that stores deadline of transmission request data D block 75
And an RMSG that stores the frame length of the data An L block 76 is provided.

Each transmission control station has a management list L2 for another transmission control station, and updates the corresponding management list L2 every time it receives a data transmission assignment request frame from another station.

As described above, each transmission control station has the management list L2 for the other transmission control stations and the management list L1 of its own station, so that the transmission request data status of the entire system can be grasped.

The flow of the frame transmission process shown in FIG.
Each transmission control station other than the master station sets the synchronization signal interrupt signal SIG2 to M
This is a processing flow executed by the MPU 27 when the PU 27 detects it, and when the MPU 27 detects the token frame normal reception completion interrupt signal SIG3 in the master station. The MPU 27 sets the data registered in the management list L1 and the management list L2 at that time as transmission permission target data, and permits transmission in the order of deadline early. Only data that can be transmitted within the remaining time T1 excluding the entire mode M1 time and the token circulation time is permitted to be transmitted. Each transmission control station knows the time T1, and determines the data that can be transmitted within the time T1 by knowing the transmission time of the frame in the order of the deadline among the data registered in the management lists L1 and L2. , N of the last data linked to the transmission queue Q2 MSG LA
And the deadline RLMSG By storing an identifier TX representing a transmission decision in D, the management list L
1 is updated (step S9). When the MPU 27 accesses the management list L1 when the transmission is completed, the management list L1 indicates the transmitted data. Next, at the next token frame reception, a data transmission assignment request frame to be transmitted as a mode M1 frame is created. In the data messages linked to the transmission request queue Q1 other than the data linked to the transmission queue Q2 in step S8, the deadline of the data is determined by the order of the deadline that can be transmitted within the time T1 in ascending order of the deadline. A data transmission assignment request frame is created by using the frame length as the information portion of the data transmission assignment request frame, and is linked to the transmission queue Q3 (step S10).

The token frame reception processing flow of FIG. 2B shows the processing flow of the token passing transmission control circuit when each transmission control station receives a token frame. First, a predetermined number of frames of mode M1 linked to the transmission queue Q3 are transmitted. At this time, a data transmission allocation request frame is broadcast (step S11). Thereafter, all data in the transmission queue Q2 is transmitted (step S12).

FIG. 2C is a flow chart of a frame transmission completion process.
Indicates that the MPU 27 detects the frame transmission completion interrupt signal SIG4
This is a processing flow executed by the MPU 27 when the processing is performed. Ma
Data message that has been transmitted by the management list L1.
Request to send all data messages
Disconnect from queue Q1. This is the N of the data message.
MSG LA and P MSG By rewriting LA
Do. At this time, it is linked to the transmission request queue Q1.
To disconnect the first data message
Page FMSG to the N of the first data message. MSG
The value of LA, FMSG D to the first message
N MSG Deadline of data message indicated by LA
MSG D and N of the first message MSG LA
P of the data message indicated by MSG LA for identifier I
Let it be T. Last link to the transmission request queue Q1
To disconnect the data message, use the data message L
MSG is added to the P of the last data message. MSG L
The value of A and its P MSG Data message indicated by LA
Page deadline MSG D for LMSG Stored in D
Then N MSG By storing the identifier IL in the LA,
Update the transmission request queue Q1 management table (step
Step S13). After that, the transmitted data transmission allocation request
The data registered in the frame, that is, the deadline
The data whose frame length is broadcast to another station is
Link using the LA in the order of deadline early. This
In the case of, the RFMSG is set to the most
N for data messages with early deadlines MSG
RFMSG as LA address D to the data
Deadline MSG of Sage RLMS
G is the slowest deadline among registered data
N of the data message to have MSG LA address and
And RLMSG By using the value of D, the management list
L1 is updated (step S14).

FIG. 2D shows the flow of the data transmission assignment request frame receiving process. This flow is a process executed when the token passing transmission control circuit receives a data transmission allocation request frame. The management list L2 corresponding to the transmission source of the received data transmission assignment request frame is updated by the information part of this frame (step S15).

FIG. 10 shows an example of using a transmission line.
When the synchronization frame 90 is transmitted from the transmission control station 1 which is the master station, it is transmitted to the transmission control stations 2 and N with a certain delay due to a propagation delay (synchronization frame detection 91). After transmitting the synchronization frame, the transmission control station 1 transmits the frame of the transmission queue Q3 including the data transmission allocation request frame, and then transmits all the frames of the transmission queue Q2. Subsequently, the transmission control stations 2 and N receiving the token frame similarly transmit the frame of the transmission queue Q3 at that time, and then transmit all the frames of the transmission queue Q2, and then update the management list L1. When each transmission control station receives a data transmission allocation request frame from another station, it immediately updates the management list L2 corresponding to the frame. When the master station receives the token frame again, it transmits a synchronization frame and a data frame and then releases the token.Here, when the master station receives the token frame, the other transmission control stations receive the synchronization frame. At this time, the combined information of the management list L1 and the management list L2 of each transmission control station is the same. Therefore, when the master station receives the token frame and the other transmission control stations receive the synchronization frame, the data to be transmitted at the next token is determined in the order earlier than the management lists L1 and L2. High data can be transmitted.

[0029]

As described in detail above, according to the present invention,
When the transmission control station receives a token frame, it has a media access control function MAC having a mode M1 function capable of transmitting a required number of data frames without fail. Assignment control of the transmission path according to it can be performed.

[Brief description of the drawings]

FIG. 1 is a flowchart of transmission request control according to the present invention.

2A is a flowchart of a frame transmission process in FIG. 1, FIG. 2B is a flowchart of a token frame reception process in FIG. 1, FIG. 2C is a flowchart of a frame transmission completion process in FIG. 1, and FIG. 9 is a flowchart of a data transmission assignment request frame reception process in FIG.

FIG. 3 is a system diagram showing a configuration example of a transmission system.

FIG. 4 is a block diagram showing a hardware configuration of a transmission control station according to the present invention.

FIG. 5 is a diagram showing a configuration example of a transmission request data message according to the present invention.

FIG. 6 is a diagram showing a configuration example of a management table of a transmission request queue Q1 according to the present invention.

FIG. 7 is a diagram showing a configuration example of a data transmission assignment request management list L1 of the own station according to the present invention.

FIG. 8 is a diagram showing a configuration example of a data transmission assignment request management list L2 of another station according to the present invention.

FIG. 9 is a diagram showing an example of a record configuration of a management list L2 according to the present invention.

FIG. 10 is a diagram showing an example of using a transmission line according to the present invention.

[Explanation of symbols]

 40 transmission request data message 50 transmission request Q1 management table 60 own station data transmission allocation request management list L1 70 other station data transmission allocation request management list L2

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/28

Claims (1)

(57) [Claims] 1. A transmission request control method in a local area network for exchanging information between a plurality of transmission control stations connected to a common transmission path, wherein one transmission control station transmits a synchronization frame for system synchronization. The token is transmitted in synchronization with a fixed time, and when a token frame indicating the transfer of the data transmission right is received, the token is released within a predetermined time.Each transmission control station transmits the necessary number of token frames when the token frame is received. A media control unit having a mode M1 capable of transmitting a data frame, a management list L1 for managing a data transmission assignment request of the own station, a management list L2 for managing a data transmission assignment request of another station, and a data transmission request. Means for assigning an identifier I1 indicating the urgency of the data to the data, and arranging the data in the transmission request queue Q1 in order of the urgency; Means for determining a data frame to be transmitted when a next token frame is received from the management lists L1 and L2 when a synchronization signal interrupt occurs, and linking the data frame to a transmission queue Q2 to which a data frame other than the mode M1 is linked; Means for creating a data transmission assignment request frame not including the determined data frame based on the transmission request queue Q1, linking the data frame corresponding to the mode M1 to a transmission queue Q3 linked as a broadcast frame; Means for transmitting a frame in mode M1 including a data transmission allocation request frame at a time and then transmitting all data frames for which transmission has been determined, and deleting the transmitted data frame from the transmission request queue Q1 when the frame transmission is completed, and transmitting the data. Make allocation request by allocation request frame Means for creating a management list L1 corresponding to the data frame, means for detecting the reception of a data transmission assignment request frame transmitted from another transmission control station, incorporating the frame into the inside, and updating the management list L2, Means for monitoring data frames transmitted from each station and deleting transmission request information from the management list L2.