JPS58213546A - Polling communication system - Google Patents

Abstract

PURPOSE:To shorten queuing time and to improve the efficiency of the whole system, by omitting polling from a master station to a slave station by each slave station address and sending common polling from the master station to slave stations. CONSTITUTION:Polling data from the master station CS includes a slave station address to be a starting point. In the figure, N1 shows the case that the starting point address is the address of a slave station TS1 and t1 shows the timing that each slave station TSi sends response data and is assigned in each slave station. Each slave station TSi compares the starting point address included in the common polling data with the self-address and calculates transmission time Ti from reception to response. If there is no data transmitted from other stations and there exists a data to be transmitted from the self-station before the arrival of the transmission time Ti, each slave station transmits the data to the master station CS. When data transmission has been already started from other station during the transmission time of the self-station, transmission from the self-station should be waited until the next common polling.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polling communication system, and particularly to a polling/selecting communication system.

In the conventional polling/selecting communication system, a master station specifies a terminal address for each terminal, that is, a slave station, polls the terminal, and invites a response. If the slave station has data to send to the master station, it sends that data, and if there is no data to send, it only sends a response to that effect. However, in such a conventional polling communication method, the above-mentioned response invitation and response processing is performed for all slave stations, so if there are many terminals, the polling cycle for each slave station becomes long, and the data is collected from data generation to collection 1. This has the disadvantage of increasing waiting time and reducing overall system efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional polling communication method described above and to provide a polling communication method that enables efficient communication.

In order to achieve the above object, the polling communication system of the present invention eliminates polling from the master station to each slave station using each slave station address, and instead sends common polling from the master station to the slave stations. That is, in the f-ring communication system of the present invention, a master station sends out a common poll that includes a slave station address as a starting point, and each slave station is assigned a time-sharing response time after receiving the common poll, and each slave station responds to the common poll. When receiving , the transmission time of the own station is calculated based on the origin address and the own station address, and when this transmission time is reached, the transmission data flash ψ If no other station has sent data before the own station, When the master station receives a response from the slave station, it receives the data, changes the origin address to the address of the slave station next to the responding station, and sends out the next common polling.

The present invention will be described in detail below with reference to an embodiment shown in one drawing.

FIG. 1 is a block diagram showing the configuration of a system in which the present invention is implemented. As shown in the figure, master station C8 and slave station TS1
. . . Tsn is the downlink transmission line L1. Upstream transmission line L
2 is connected in a multi-drop manner.

In this system, the master station C8 sends common polling data to the slave stations TS1, TS2, . . . , through the downlink transmission path L1. This polling data includes the slave station address i that is the starting point. An example of this common polling data is shown in Figure 2 (a), where Nl is the starting point address when the slave station Ts1 address is shown. In addition, the tl- shown in Figure 2(b) is also
---- ・tn is each slave station TS1, TS2...
- '1' S n indicates the response timing for sending response data to the master station, and these times are allocated to each slave station in a time-sharing manner.

The common polling data transmitted to the downlink transmission path L1 is received by each slave station TS1, TS2, . . . 'l' S n. When each slave station TS1, TS2, -, TSR+ receives the common polling data, it compares its own address with the origin address included in the common polling data, receives the common polling data, and then responds.Transmission time T in 1
1.T2.-.Tn [see FIG. 2(C)] is calculated.

Each slave station T S 1, T S 2...T 8n, when the transmission time T1, T2...T n arrives, there is no data sent from other stations before then, and the data sent to the own station is However, when the transmission time of 0, which sends data to the main SO8 via the upstream transmission path L2, reaches its own transmission time, if data transmission from other stations has already started, it will receive the 6th common polling data. I'll have to wait in the trench.

Note that the response timings t1 and 2 are set to the minimum value, with the interval of 1 being the value necessary for receiving and determining the sending of common polling data and the sending of other terminals.

In response to common polling from master station O8, slave station Il
When a response is received from lS, the main station C8 changes the starting point address to i+1 when transmitting the next common polling.

As an example, FIG. 6 shows a case where the second slave station TS2 sends response data in response to common polling N,1 (see (11) in Figure z3) whose starting address is the first slave station T81. The time chart shows the response timing of slave station 1'S2 which receives common polling N1.
When the main station C8 transmits the transmission data [see FIG. 5(C)] in the transmission text of the data generated in its own station, the main station C8 next transmits the common polling N3. This common poll N3
The previous address data is used as the starting point address data, and the response slave station 1. '
Contains the address L3 of the slave station TS3 next to S2 [see Figure 6 (1)] 0 As described above, the response to the common polling by the slave station is based on the origin address 1 included in the common bore link data. A time-division cheesy chain method is used to set the highest level, and when the high-level slave station IllS; responds, the starting point address included in the next common poll sent out is the slave station of the previous response + 1 + the next slave station TS i of Si.
The address is changed to +1 so that the priority of poll link responses is not biased.

Next, a control flow for concretely proceeding with the transmission/reception processing of the polling communication method of the above-described embodiment will be explained.

FIG. 4 shows the control flow of the main station C8.

When the operation starts, initialization processing is first performed, and the polling start address (for example, in the case of Fig. 2, slave station T
s1 address) and the monitoring timer. Although not shown, these settings are made in the starting address storage area and the monitoring timer area of the memory provided in the main station (step STM). Next, send out common polling. That is, the common polling data including the starting point address is sent to the slave stations Ts], Ta2, . . . , Tsn via the downlink transmission path L1 (ST2). Next, it is determined whether there is a response from any slave station (5T3), and if there is no response from any slave station, it is determined whether the monitoring timer has timed up or not (T'4'). ST3 until there is a response. Repeat the operation of ST4.

When a response from the slave station is determined in ST3.

Receive text from the slave station L (ST5'),
Determine whether there is an error in the received data (ST
/,'). If an error is detected, compare the preset number of retransmissions and the current number of retransmissions (initially 0), and if the number of retransmissions does not exceed the set number of times (S
T7) issues a retransmission request to the slave station that sent the text (ST8). Then, it receives the text sent by the slave again (s'r5) and performs an error judgment (S'r5).
T6). If an error occurs, it is determined whether the number of retransmissions has been exceeded in ST7, and a retransmission request is made in ST8, and retransmission and reception are repeated. However, if an error still occurs even after the number of retransmissions exceeds the set number, it is abnormal. It is determined that the error is recorded (ST9).

If there is no error in the determination in ST6, predetermined processing is performed on the received data (ST10), and then the starting point address is changed. This change can be done, for example, by updating the address of the slave station TSI to the address of the slave station with the next priority after the slave station that sent the text (the slave station whose response order is next in priority), as described above. It is done.

Note that even after the abnormal recording in ST9, the starting point address is changed in ST11. In this case as well, the address is updated to the address of the next priority slave station after the slave station that sent the text.

The main station that has changed its starting point address sends out a common poll that includes this new starting point address (5T2).

After that, repeat the same operation as described in section 2.

FIG. 5 shows the control flow of each slave station Tsi, Ta2, . . . , Tsn. After starting the operation, it is determined whether or not common polling data from the main station C8 has been received (ST20).

This step ST20 remains until the common polling data is sent from the main station C8.

When the common polling data is received, it compares the origin address included in the common polling data with its own address and calculates the transmission time of its own data (ST21).
. Then, it is determined whether or not there is transmission data to be sent from the own station to the main station (ST22). If there is no transmission data in the own station, there is a 9-wait period for starting. For example, the time elapsed after receiving the common polling data is measured and it is determined whether the time has reached the transmission time of the own station calculated in ST21 (5T23).If the transmission time of the own station has not been reached, the other station monitors whether the main station is transmitting data to the main station C8 (ST24).This monitoring continues until the transmission time of the own station is reached or transmission data of another station is detected.In ST24, When transmission data is detected, it waits until the 9th common polling reception from the start.

When the transmission time of the own station is reached in a state where no received data of υ is sent from other stations, the text is transmitted to the main station C8 via the upstream transmission path L2 (ST25). After the transmission is completed, there is a retransmission request from the main station C8, and if this is received (ST26), the text transmission is performed again. If there is no retransmission request, the communication is completed and the process returns to the start.

As described above, according to the polling communication system of the present invention, the master station sends out a common poll including the slave station address that is the starting point, and the response time after receiving the common poll is allocated to each slave station in a time-sharing manner.

When each slave station receives the common polling, it calculates its own transmission time based on the origin address and its own address, and when the transmission time is reached, if there is data to be sent, the slave station or the other station has already sent data. Since the transmit data is sent only when there is no data to be sent, it does not respond to each slave station individually by address specification to indicate the presence or absence of data, as in the conventional system. In this case, the time required for sending the common polling data and detecting and determining the data transmitted by other stations is enough, so the polling period can be shortened and the efficiency of the entire system can be increased.

If the master station receives a response from the slave station, it receives the data, changes the origin address to the next slave address of the responding slave station, and sends out the next common poll, so the response priority level is dispersed and communication with the master station is interrupted. It is possible to avoid relying too heavily on specific subordinates.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a system in which this invention is implemented, FIGS. 2 and 5 are time charts for explaining the first embodiment of this invention, and FIG. Figure 3 is a diagram showing the relationship between response timing assignments and response times. Figure 3 is a diagram for explaining the text transmission timing when there is a response to common polling and the change in the starting point address of the next common polling. Figure 4 is a diagram showing the relationship between response timing allocation and response time. FIG. 5 is a diagram showing the control flow of the master station in FIG. 1, and FIG. 5 is a diagram showing the control flow of each slave station in FIG. C8: Master station, TSl/TS2...TSn: Slave station. Ll: Downlink transmission line, L22 uplink transmission line. Patent Applicant Tateishi Electric Co., Ltd. Agent Patent Attorney Shinji Naka Toshige 4th Funeral 5th

Claims (1)

[Claims] (1) Polling is performed from the master station to multiple slave stations. In a polling communication method in which data is exchanged between a master station and a slave station in response to a response from a slave station. The master station sends out a common poll that includes the slave station address that is the starting point, and each slave station is assigned a time-sharing response time after receiving the common poll. The transmission time of the own station is calculated by A polling communication system characterized in that when a response is received from a slave station, the station receives the data, changes the origin address to the slave station address of the next rank of the responding station, and sends out the next common poll.
i method.