JPS62145945A - Polling control system - Google Patents

Abstract

PURPOSE:To relieve the load of a central processing unit by adding a function applying polling of a terminal equipment to a communication control equipment according to the content of a station address table from the central processing unit, a transmission control field table and a reception control field table. CONSTITUTION:The communication control equipment 2 is connected to the central processing unit 1, and plural terminal equipments T1-Tn are connected to the communication control equipment 2 via a communication line 3. The communication control equipment 2 includes a pointer table 20, a station address table 21, a communication control field table 22, a reception control field table 23, a transmission frame register 24 and a reception frame register 25 used respectively for the polling control and they are rewritable from the central processing unit. Thus, the polling function is shared to the communication control equipment 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a polling control method for a system that transmits data using a high-level data link protocol, and particularly in a system where a large number of terminals are connected to a communication control device and data is transmitted. The present invention relates to a polling control method that improves the processing capacity of a central processing unit by minimizing information transfer between a communication control device and a central processing unit in a system where polling occurs randomly.

[Conventional technology]

Conventionally, the polling system fffl for UN class-next stations has been carried out by the central processing unit, and the communication control unit has only been responsible for adding and deleting flag sequences (F) and adding and checking frame check sequences (Fe2). Met. Therefore, each time polling and frame transmission and reception are performed, information is transferred between the central processing unit and the communication control unit.

[Problem that the invention seeks to solve]

In the conventional polling control method described above, most of the processing is concentrated in the central processing unit, so the response frame from the polling terminal (secondary station) does not have an information part and is just a response to the polling. Sending confirmation,
Even frames that do not trigger state transitions such as error or busy messages involve the transfer of information between the control unit and the central processing unit. In this state, the information transfer between the central processing unit and the communication control unit due to polling control on the primary station side is completely wasteful, and this causes a decline in the processing capacity of other tasks in the central processing unit.

The present invention has been made in view of these circumstances,
The purpose is to provide a polling control method that can reduce the load on the central processing unit during polling as much as possible.

[Means for solving problems]

In order to achieve the above object, the present invention includes a central processing unit;
In a polling control method in a system including a communication control device connected to the central processing device and a plurality of terminals connected to the communication control device, the communication control device includes a station that can be rewritten from the central processing device. address table, transmission control field table,
A reception control field table is provided, and the communication control device polls the terminals registered in the station address table using the transmission control field stored in the transmission control field table, and acquires the transmission right by the polling. When a response frame is received from the terminal that gave the transmission right, the reception control field in the response frame is compared with the reception control field corresponding to the terminal that gave the transmission right in the reception control field table, and if they match, The next terminal is polled, and if there is a mismatch, the polling control 1 operation is interrupted and the central processing unit is interrupted.

[Effect]

If the content of the reception control field table is updated by the central processing unit so that it is the same as a response frame without data, for example, when a response frame without data is received from the terminal, an interrupt is sent to the central processing unit. Therefore, the load on the central processing unit can be reduced accordingly.

When a response frame with data is received from the terminal, the reception control field in the response frame and the reception control field in the reception control field table do not match, so an interrupt is generated in the central processing unit.
This interrupt processing allows the received data to be passed to the central processing unit.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an example of a system to which the present invention is applied, in which a communication control device 2 is connected to a central processing unit 1, and a plurality of terminals in a branch configuration are connected to the communication control device 2 via a communication line 3. T1=Tn indicates a connected system.

The communication control device 2 includes pointer tables 20 . . . , which are used for polling control. Station address table 21. Transmission control field table 22. Reception control field table 23. Transmission frame register 24. A receive frame register 25 is included, and these can be rewritten by the central processing unit 1.

The pointer table 20 includes a transmission control field table pointer SP, a station address table pointer AP, and a reception control field table pointer RP.

Current terminal number m (1≦m≦n), last terminal number n
are stored, the station address table 21 stores station addresses At to An of terminals to be polled, and the transmission control field table 22 stores transmission control fields CI(S) to Cn(S) of each terminal Tl-Tn. are stored in the reception control field table 23, and each terminal T1 to T
n reception control fields C1(R) to Cn(R) are stored. The transmission frame 24 is a frame transmitted to the terminal via the communication line 3, and includes a flag sequence F7 station address Am, a transmission control field Cm (S), and a flag check sequence FC8. The received frame 25 is a frame received from the terminal via the communication line 3, and includes a flag sequence F1 station address Am, a reception control field Cm(R), a flag check sequence FC8, and in some cases a data section (not shown). is included. The above transmission control fields CI(S) to Cn(S
) includes the serial number of the data sent from the terminal to the communication control device 2, and the reception control fields c 1 (R) to C
n(R) includes the presence or absence of data, the presence or absence of a busy state, and the serial number of data sent from the communication control device 2 to the terminal.

First, the operation of the communication control device 2 will be explained with reference to the flowchart shown in FIG.

Upon receiving the instruction to start polling from the central processing unit 1, the communication control device 2 confirms that no instruction to interrupt polling has been issued from the central processing unit 1 (31), and then inputs the current terminal number m in the pointer table 20. →What's up S2
), the station address A corresponding to this current terminal number m
A search is made to see if m is registered in the station address table 21 (S3). Then, if it is not registered, return to step S1 and repeat the above process, and if it is registered, obtain the transmission control field Cm(S) of that terminal from the transmission control field table 22 (S4).
, this transmission control field Cm(S) and the station address Am
is set in the transmission frame 24 (S5), F and Fe2 are added thereto, and the frame is sent out on the communication line 3 (S6).

After transmitting the above frame, the communication control device 2 waits for reception confirmation of the received frame (S7), and when the received frame 25 from the terminal is received, the station address Am in that frame is included in the frame transmitted in step S6. Compare the station address Am corresponding to the current terminal number m.S
8), -4&, the received frame is discarded because it is transmitted from a terminal that does not grant transmission rights (S
9).

If they match, the control field Cm (R) in the received frame is compared with the reception control field Cm (R) in the reception control field table 23 corresponding to the current terminal number m included in the frame sent in step S6. (SIO). If the contents of both control fields match, the process returns to step S1 and the above operation is repeated. On the other hand, if there is a mismatch, the polling control operation is interrupted and the central processing unit 1 is notified by an interrupt (Sll).
A state is entered during polling suspension processing (S12). In this polling suspension process, all received frames are notified to the central processing unit 1 by interrupt. Further, when a polling restart instruction is sent from the central processing unit 1, step S
1 and restarts the polling control operation (S13).

When the polling restart instruction is received from the central processing unit l, it is identified in step Sl, and the polling control operation is interrupted and a notification to that effect (polling interruption notification) is sent to the central processing unit l (514). When there is a frame transmission request from process 11affl (S1
5), performs processing according to its type, that is, data link establishment, data link release, and data transmission from the central processing unit 1 to the terminal (S L6 to 318), and the central processing unit [
When a polling restart instruction is issued from (319), the process returns to step S1 and the polling control operation is restarted.

Next, the operation when establishing a data link will be explained.

FIG. 3 shows terminal T2. T3. T4 is a terminal in the data link establishment method, and a sequence is shown in which the central processing unit l newly establishes a data link for the terminal T5,
RR3P, RRIP, R1'? 2P and RROP are the contents of the transmission control field in the frame sent from the communication control device 2 to the terminal, RR6F, RR5F, RR7F,
RROF is the content of the receiver control field in the frame sent from the terminal to the communication control device 2, SNRMP is the content of the transmission control field in the data link establishment frame, and UAF is the acknowledgment signal from the terminal. , 4th
The figure is a flowchart showing an example of the data link establishment process of the central processing unit l.

As shown in FIG.
When a polling interruption instruction is sent from the central processing unit 1 (S20) during polling in which frames are exchanged between Then, a polling interruption notification is sent to the central processing unit 1 (S14). When the central processing unit 1 receives this notification (S21), it sends a request to transmit a data link establishment frame to the communication control unit 2 (
S22).

Note that this request is made by the terminal T5 that establishes the data link.
Station address A5. Includes the above SNRMP.

When the communication control device 2 receives this frame transmission request (S
15), terminal T through data link establishment processing (517)
Terminal T sends a data link establishment frame to terminal T.
Upon receiving an acknowledgment signal from IS 5, it sends a frame reception notification to central processing unit 1 and waits for an instruction to resume polling.
19). When the central processing unit 1 receives the frame reception notification from the ij1 communication control device 2 (S23), the central processing unit 1 receives the frame reception notification from the communication control device 2.
The station address A5 of the terminal T5 is written in the station address table 21 in the transmission control field table 22.
The transmission control field C5 (S) of the terminal T5 is written in the reception control field table 23, the reception control field C3 (R) of the terminal T5 is written in the reception control field table 23 (S24), and a polling restart instruction is sent (S25). The communication control device 2 resumes the polling control operation that had been interrupted by this polling restart instruction (S19).

In this way, the data link is established by temporarily suspending the polling operation of the communication control device 2 by the central processing unit l, and writing the station address of the terminal for which the data link is to be established to the communication control device 2. As a result, the terminal T5 is added to the polling target as shown at the end of the sequence in FIG.

Next, the operation when releasing the data link will be explained.

FIG. 5 shows the sequence in which the terminals T2 to T6 are the terminals in the data link establishment method, and the data link of the terminal T5 is released from there. In FIG. 5, the same reference numerals as in FIG. 3 indicate the same parts, and DISCP indicates the contents of the transmission control field in the data link release frame. Further, FIG. 6 is a flowchart showing an example of data link release processing of the central processing unit 1.

As shown in FIG. 5, during polling when the communication control device 2 is exchanging frames with the terminals T2 and T3,
When a polling interruption instruction is sent from the central processing unit 1 (S30), the communication control device 2 identifies this in step Sl, interrupts the polling control operation, and sends a polling interruption notification to the central processing unit 1 (S 14). When the central processing unit 1 receives this notification (S31), it sends a data link release frame transmission request to the communication control unit 2 (S32).

Note that this request is sent by the terminal T5 that releases the data link.
Station address A5. Includes the above DISCP.

Upon receiving this frame transmission request, the communication control device 2 transmits (5
15) Sends a data link release frame to terminal T5 through data link release processing (31B), and upon receiving an acknowledgment signal from terminal T5, sends a frame reception notification to central processing unit 1 and waits for polling restart instruction. (3
19). When the central processing unit 1 receives the frame reception notification from the communication control unit 2 (S33), the central processing unit 1 updates the station address of the terminal T5 in the station address table 21 in the communication control unit 2.
, or is set to 0 (534), and sends a polling restart instruction (335). The communication control device 2 resumes the suspended polling control operation in response to this polling restart instruction (S19).

In this way, the data link is released by temporarily suspending the polling operation of the communication control device 2 by the central processing unit 1, and deleting the station address of the terminal from the central processing unit 20 station address table 21. As a result, terminal T5 is excluded from the polling target as shown at the end of the sequence in FIG.

Next, the operation when transmitting data from the central processing unit 1 to the terminal will be explained.

FIG. 7 shows data sent from the central processing unit 1 to the terminal Tm (,
The sequence when = is illustrated focusing only on the terminal Tm, where IO, OP, + 1, 0π indicate the contents of the transmission control field in the frame for transmission data, and ■ indicates the presence of data. The first O and 1 are the serial numbers of the transmitted data, the first 0 and O are the serial numbers of the received data, and r is an identification code indicating that the frame is not the last transmitted data frame. Further, FIG. 8 is a flowchart showing an example of data transmission processing by the central processing WRt.

As shown in FIG. 7, when a polling interruption instruction is sent from the central processing unit 1 during polling when the communication control device 2 is exchanging frames with the terminal Tm (S4
0), the communication control device 2 identifies this in step S1, interrupts the polling control operation, and sends a polling interruption notification to the central processing device 1 (S14). Here, terminal T
The content of the receive control field of the last frame from m is RROF. When the central processing unit I receives this notification (
S41), and sends a transmission request for the first transmission data frame to the communication control device 2 (S42). Note that this request includes the station address Am of the terminal Tm transmitting data, and the above 10.000. When the communication control device 2 receives this frame transmission request (315), it performs data transmission processing (S16).
) sends a data transmission frame to the terminal Tm. Such processing is carried out until the transmission frame ends (S43), and when the sending of the frame for transmission data after i is completed, the central processing unit 1 sends a polling restart instruction (544), which causes the communication system Vn device to 2 returns to step S1 and restarts the polling control operation (S19
). During this time, the terminal Tm that received the data updates the serial number of the received data, but the contents of the reception control field of the terminal Tm in the reception control field table 23 of the communication control device 2 are retained as they were at the time of interruption (RROF). There is. Therefore, when the communication control device 2 restarts the polling control operation and performs the next polling on the terminal Tm, in step SIO, the contents of the reception control field (RR2F) from the terminal Tm and the reception control field table 2
Contents of the reception control field corresponding to the terminal Tm in 3 (RR
OF) will be detected. The central processing unit 1 confirms the transmission by detecting the interrupt notification due to this mismatch (S45), and when the transmission confirmation is completed, the receiving side of the communication control unit 2 updates the terminal in the COU field table 23. The content of the reception control field of Tm is updated from RROF to RR2F to resolve the mismatch in serial numbers (346), and a polling start instruction is sent to cause the communication control device 2 to restart the polling operation.

Next is the central processing unit? The operation when H receives data from a terminal will be explained.

FIG. 9 shows the sequence when the central processing unit 1 receives data from the terminal Tm, focusing only on the terminal Tm. Indicates the contents of the control field, I is a code indicating the data, the first O and 1 are the serial number of the transmitted data, the second 2 and 2 are the serial number of the received data, and V is the identification code indicating that it is not the last received frame. It is. Also, the 10th
The figure is a flowchart showing an example of data reception processing of the central processing bag ff1l.

As shown in FIG. 9, during polling in which the communication control device 2 exchanges frames between the terminals Tm,
If the reception control field IO, 2F indicating that there is transmission data is included in the frame from m, the reception control field Cm of the terminal Tm in the reception control field table 23 is
Since the content of (R) is RR2F with no data, a mismatch is detected in step SIO, and the central processing unit t is notified by an interrupt. When the central processing unit 1 receives this interrupt notification that there is received data, it sends a final reception notification (in FIG. 9, an RR in the reception control field) as shown in FIG.
Waiting for a reception notification corresponding to a frame containing 2F (S50), the content of the transmission control field of the terminal Tm in the transmission control field table 22 is updated from RROP to RR2P (551), and a polling restart instruction is sent. (S52). In response to this polling restart instruction, the communication control device 2 enters the ST.

The polling control operation is restarted from step 31.

Next, the operation when the other station is busy will be explained.

FIG. 11 shows the sequence when a busy state is generated and released at the terminal Tm, focusing only on the terminal Tm, and RNR is the busy occurrence included in the reception control field of the frame from the terminal Tm. This is a code indicating. Further, FIG. 12 is a flowchart showing an example of busy processing of the central processing unit 1.

As shown in FIG. 11, when the communication control device 2 receives a frame including an RNR indicating a busy occurrence from the terminal Tm, the content of the reception control field Cm(R) of the terminal Tm in the reception control field table 23 is set to the receive ready state ( For example, RR6F), a mismatch is detected in step SIO, and the central processing unit 1 is notified by an interrupt. When the central processing unit l receives this interrupt notification, it changes the contents of the reception control field corresponding to the terminal Tm in the reception control field table 23 to R[? (Receive Ready) to RNR (Receive Not Ready) (3
60, 361), sends a polling restart instruction to the communication control device 2. In response to this polling restart instruction, the communication control device 2 restarts the polling control operation from step S1. Therefore, when terminal Tm is polled next time,
Even if the RNR indicating the occurrence of a busy event is included in the reception control field of the reception frame, the content of the reception control field of the terminal Tm in the reception control field table 23 has been changed to RNR, so an interrupt notification to the central processing unit 1 is not sent. is not carried out. Thereby, the load on the central processing unit 1 can be reduced. A frame containing an RR indicating that the terminal Tm has been released from busy (RR6F in FIG. 11)
is received, step 310 of the communication control device 2 is performed again.
When a mismatch is detected in 360., the central processing unit 1 changes the reception control field corresponding to the terminal Tm in the reception control field table 23 from RNR to RR. 56
2) Send a polling restart instruction to the communication control device 2 to restart polling.

As described above, in this embodiment, by assigning the polling function to the communication control device 2, the station address table 21.
This is limited to procedural recovery processing such as update processing of the transmission control field table 22 and reception control field table 23, and information transmission between terminals, and the load on the central processing unit can be sufficiently reduced.

〔Effect of the invention〕

As explained above, the present invention adds to the communication control device the function of polling terminals according to the contents of the station address table, transmission control field table, and reception control field table that can be rewritten from the central processing unit. The load on the central processing unit is reduced, and whether or not to interrupt the central processing unit is switched based on the comparison result between the reception control field in the response frame and the reception control field in the reception control field table. If the content of the control field table is updated in the central processing unit so that it has the same content as a response frame with no data, for example, when a response frame with no data is received from the terminal, an interrupt will be sent to the central processing unit. This makes it possible to further reduce the load on the central processing unit.

[Brief explanation of drawings]

1 is a block diagram showing an example of a system to which the present invention is applied; FIG. 2 is a flowchart showing an example of processing of the communication control device 2; FIG. 3 is a sequence chart for establishing a data link; The figure is a flowchart showing an example of the data link establishment process of the central processing unit 1, Figure 5 is a sequence chart when releasing the data link, and Figure 6 is an example of the process of the central processing unit 1 when releasing the data link. FIG. 7 is a sequence chart when transmitting data, FIG. 8 is a flow chart showing an example of data transmission processing by the central processing unit l, FIG. 9 is a sequence chart when receiving data, and FIG. Figure 11 is a flowchart showing an example of data reception processing in No. 1. Figure 11 is a sequence chart during busy processing.
The figure is a flowchart showing an example of busy processing by the central processing unit 1. In the figure, 1 is a central processing unit, 2 is a communication control unit, and 3 is a central processing unit.
is a communication line, 20 is a pointer table, 21 is a station address table, 22 is a transmission control field table, 23
is a reception control field table, 24 is a transmission frame,
25 is a received frame, and T1 to Tn are terminals.

Claims (1)

[Scope of Claims] A polling control method in a system including a central processing unit, a communication control device connected to the central processing unit, and a plurality of terminals connected to the communication control device, comprising: a station address table and a transmission control field table that can be rewritten by the central processing unit;
A reception control field table is provided, and the communication control device polls the terminals registered in the station address table using the transmission control field stored in the transmission control field table, and acquires the transmission right by the polling. When a response frame is received from the terminal that gave the transmission right, the reception control field in the response frame is compared with the reception control field corresponding to the terminal that gave the transmission right in the reception control field table, and if they match, A polling control method characterized in that the next terminal is polled, and if there is a mismatch, the polling control operation is interrupted and an interrupt is made to the central processing unit.