JPS58213548A - Method for transmitting polling - Google Patents

Abstract

PURPOSE:To detect recovery automatically and to shorten polling time, by separating a downed slave station from normal polling and sending common polling to make a restored slave station output a recovery response and insert the restored slave station into the normal polling again. CONSTITUTION:When the slave stations TS2, TS5 are downed, pollings N2, N5 are removed, and when the slave station TS2 has the priority, a common polling C2 is inserted into the last position of a normal polling string. The normal polling includes the processing to supervise time at the no response of the slave station and the common polling waits only the minimum time to check the recovery response from the downed terminal and then moves to the normal polling N1 immediately. When only the slave station TS5 is restored, the slave station TS5 sends a recovery response to the master station CS when the response time of the self-station is reached after passing the time of T5 from the reception of the common polling C2. Receiving said recovery response, the master station CS inserts the normal polling N5 for the slave station TS5 from the next polling group. After receiving the normal polling N5 after recovery, the slave station TS5 loses the right of response to the common polling.

Description

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

In the conventional polling/selecting transmission method,
If a terminal that is a slave station stops responding to polling due to a power outage or abnormality, that is, if the terminal goes down, the error of no response will be reported to the upper layer, and subsequent polling loops will continue to poll as normal. Either the error is gaunted and the error is reported to the higher level each time it occurs, or the terminal is removed from the polling loop after a certain number of errors are gaunted. However, since the above method detects each non-response, it has the disadvantage that time management processing for non-response is performed and the overall polling loop becomes longer. There is no detection means in the main station, and two people have to manually set the return state in the main station by operating keys, which is very troublesome. Furthermore, it is not desirable for the system to involve human operations.

The purpose of the present invention is to eliminate the drawbacks of the conventional polling transmission method described above, and to provide a polling transmission method that can shorten the polling cycle and allow a master station to automatically detect the return of a slave station (terminal) that has gone down. It is in.

In order to achieve the above object, the polling transmission method of the present invention sequentially sends regular polling including individual addresses to each slave station from the master station, and if there is no response from each slave station, regular polling is performed with that slave station as a down terminal. At the same time, if there is a non-responsive slave station, following the regular polling, a common poll including the unresponsive slave station address to which the highest priority response priority is attached is sent, and the non-responsive slave station to which the highest priority response priority is assigned is sent. Subsequent slave stations (response time after receiving common polling are allocated in a time-division manner, and when each non-responsive slave station recovers from down and receives the common polling, the slave station address and own station address included in this common polling are Calculate your own station's transmission time.

When this transmission time is reached, if no other station has transmitted before the own station, a return response is sent to the master station, and the master station that receives this return response regularly polls the slave station that sent the return response. I'm trying to get it back inside.

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

FIG. 1 is a schematic block diagram of a system in which the present invention is implemented. In the figure, the main station C8 is connected to the lower transmission line L1. The slave station TSi/
TS2...Connected to TSn.

In the system shown in FIG. 1, slave stations Tl and TS2...
...TSn are normal, the master station C8 sends regular polling to each slave station TSi, TS2, ...TSn. This regular polling is sent in the second
As shown in the figure, polling N1 containing the address of slave station TS1 is first sent to slave station TS1, and then polling N1 containing the address of slave station TS1 is sent to slave station TS1.
Polling N2, N5...Nn including the respective slave station addresses is now sent to S2, TS3...TSn.

The response data from any terminal, that is, the slave station, is sent to the master station C8.
N1, N2...N shown here unless sent to
The sending of n polling groups is repeated. The repetition of such polling loops is no different from the conventional polling transmission method.

However, some terminals were down and regular polling N1
・N2...N When a non-responsive slave station occurs for N n K, in this embodiment, this non-responsive slave station is excluded from regular polling, and the main polling is performed only for the remaining normally operating and starved stations. The station sends out a regular poll. Then, following the regular polling, a common polling is sent out to give the down slave station a chance to respond with a recovery response. This common polling is sent out by specifying the slave station address with the highest priority Ω among the downed terminals.

The response priority of each down slave station to common polling is conveniently determined in accordance with the order of regular polling.

Furthermore, a terminal that has not received regular polling even once after powering on is eligible to respond to common polling as a terminal that has returned after going down, but a terminal that has received regular polling even once does not respond to common polling.

A slave station that returns after going down calculates its response time from the highest priority slave station address included in the common poll and its own address.

The response time interval between slave stations with the same priority is
When a terminal with a higher priority sends a response to the master station,
Even if a terminal with a low priority reaches its own sending time, by detecting the transmission from a station with a higher priority, the terminal has enough time to not send its own response to the main station.

An example of the polling loop of this embodiment including regular polling and common polling is shown in FIG. The example in Fig. 6 shows a case where slave stations TS2 and TS5 go down, and shiboring rings N2 and N5 are removed and slave stations TS2 and TS5 go down.
Common poll C2, which includes terminal address No. 2 as the highest priority response address, is inserted at the end of the regular poll sequence.

The difference between regular polling and common polling is that regular polling includes error handling such as time monitoring and polling retransmission when a slave station does not respond.

The common polling has only the minimum time to confirm the return response from the downed terminal, and then immediately shifts to regular polling N1. Therefore, check the status of down terminals during regular polling.
Confirmation using common polling will take less time.

Next, a processing method when the slave station TS5 returns to normal operation in the example shown in FIG. 3 will be described. FIG. 4 shows an enlarged time chart when common polling C2 is sent in that case. In FIG. 4, (a) shows the polling transmission timing from the master station C8 and the response time allocated to the slave station of the down terminal, and (2) shows the highest priority response included in the common polling data C2. t5 is the response time assigned to the slave station (in this example, slave station TS2) corresponding to the slave station address, and t5 is the response time assigned to the slave station TS5 of the terminal that is also down.
shows the response time allocated to

Of the slave stations TS2 and TS5 that are currently down, slave station TS5
Suppose that the slave station TS5 has recovered, the slave station TS5 receives the common polling C2 from the master station C8, and from its own address (=5) and the highest priority response slave station address (=2) included in the common polling C2, ( 5-2) Perform the calculation of XK+α=T5. Here, α is 1 when the own station receives the common polling C21 or the slave station with higher priority receives the response from the master station C8.
This is the time required to confirm what has been said, and K is the margin time to ensure that the responses from the terminal that is down do not overlap. Both α and - have variable values depending on the system.

As shown in FIG. 4(b), the slave station TS2 has not returned from being down, so even after the time T2=α has elapsed and the own station's response time L2 has been reached after receiving the common polling C2, it does not respond to the return response. , the slave station TS5 has recovered from being down, so when the time T5 has passed after receiving the common polling C2 and the own station's response time has been reached, it sends a recovery response to the master station C8 as shown in Figure 4 ((1)). Send.

When the master station CS receives the return response from the slave station TS5, it inserts a regular poll N5 for the slave station TS5 from the ninth polling loop. The state is shown in FIG. When slave station TS5 receives regular polling N5'f: after returning, it loses the qualification to respond to common polling.

In the example of FIG. 3, slave station TS2. A processing method when both TS5 return before sending the common polling C2 will be explained with reference to the time chart shown in FIG.

Slave station TS2. When each TS5 receives the common polling C2, it calculates its own response time α, T5, and waits. Then, when time α has elapsed after receiving the common polling C2, the slave station TS2 sends a return response to the master station C8 [see FIG. 6(b)]. On the other hand, when the slave station TS5 receives the return response from the slave station TS2, it interrupts sending the scheduled return response when its own response time is 5 [see Fig. 6(c)], and the next common boring is sent. Wait until. Main station C
Upon receiving the return response from slave station TS2, 8 cancels the scheduled wait time until regular polling N1, immediately shifts to regular polling N1, and inserts regular polling N2 for slave station TS2 into the regular polling queue. do.

In addition, in the explanation in section 2, we assume a case where slave stations TS2 and TS5 are down, and we will exclude these slave stations from regular polling, and reinsert the restored slave stations into the regular polling queue in response to the common polling upon recovery. However, similar processing is performed even when many other slave stations go down and then come back up again. In this case, if multiple slave stations return at the same time, they will be inserted into the regular polling queue in order from the one with the quickest response time allocation (highest priority) as described above, and the slave stations with lower ranks will be inserted into the regular polling queue in order. Wait until common polling arrives.

More specific operations of the above-mentioned exclusion from normal polling and reinsertion into normal polling by return response are explained in the seventh section.
The control flow of the main station C8 shown in the figure.

This will be explained with reference to the control flow of slave stations TSI, TS2, . . . TSn shown in FIG.

As shown in FIG. 7, the main station C8 first performs initialization processing when the power is turned on or the operation is started by resetting (step 5TI). That is, the polling activation flags of all connected terminals (all slave stations) are set, and the address of the first slave station TS1 is set in the polling address area. Note that the polling activation flag and polling address area are arranged in a memory built in the processing device of the main station C8.

Following the initialization of ST1, normal polling N1 is sent to the previous slave station TS1 (ST2), and the slave station T
It is determined whether there is a response from S1 (ST3). If there is a response, normal processing is performed, that is, a no-data response is received or sent data is received (ST4). Next, it is determined whether polling of all target slave stations has been completed (ST5).
), the decision is NO at first and the symbolic address is updated (ST6).

Then, regular polling is sent to the slave station with the updated address. While updating the polling address as long as there is a response to the regular poll.

ST2→STro-→5T4-→5T5-→ST6→ST
Repeat process 2.

If there is no response from the slave station in ST3, the terminal is assumed to be down, the polling start flag corresponding to this address is reset, and the terminal is separated from the polling target. That is, the slave station is excluded from regular polling (ST7).

Thereafter, the polling address is updated (ST6) and the process moves to regular polling of the next slave station.

When the regular polling of all target slave stations is completed as described above, it is determined whether or not there is a terminal that is down by referring to the polling start flag (ST8).

If there is no terminal that is down, the process returns to ST2 after updating the polling address in ST6 and moves on to the operation of the next regular polling loop. On the other hand, if there is even one down terminal in ST8, the address with the highest priority among the down terminals is set as the starting address in the polling address area, and the address with the lowest response priority among the down terminals is set. The return response time is calculated and a common poll is sent out (ST9). If there is no return response from any of the slave stations of the down terminal in response to the common polling (STIO), the start address of the 9th polling loop is set in the polling address area.
L, (ST12) Return to ST2 and proceed to the operation of the next regular polling loop.

When there is a return response at 5TIO, the return processing is performed by setting the polling start flag for the terminal that received the response (5T11), and the process returns to ST2 via ST12, and the next normal polling loop operation begins. Move.

On the other hand, each slave station TS1, TS2, . . . TSn resets the ready flag and stores the initial state when the power is turned on or the operation is started by reset (ST21). Note that the ready flag is stored in the memory built in the processing device of each slave station. After resetting the ready flag, it is determined whether polling data has been received (5T22), and if it is polling reception, it is determined whether the ready flag is on (ST23).

If the ready flag is reset and is not turned on, it means that the polling reception is reception on the initial (initial) line, and then it is determined whether the polling reception is regular polling or common polling (ST24). If it is a regular polling reception, set the ready flag (ST
25) L, response processing to regular poll link (response with no data or data sending response) L (ST26),
It returns to ST 22 and waits until the next polling reception.

If it is a common polling reception in ST24, it means that the state has returned from the town state to the initial state rB which is ready for operation.The response time of the own station is calculated from the highest priority response slave station address during common polling and the address of the own station, Start the timer (ST27). Then, it monitors whether a return response is sent from another station with a higher priority until the response time of its own station is reached. If a return response from another station is detected before the timer times up, that is, before the own station's response time comes, the timer is reset (ST28, 5T29), and ST
2 to Motoshi.

Wait until the next common poll arrives. If the own station's response time arrives before the other station sends a return response, it sends a return response to the main station CS (ST30).

Although the above embodiment describes the case of a two-wire system, if the transmission line is a four-wire system and the transmitting line and receiving line are separated, the master station that receives the return response will send a message to that effect to the slave station. By transmitting this as a response to the return terminal, a returning terminal with a lower response order can receive this and abandon its own scheduled return response.

As described above, according to the polling transmission method of the present invention,
If a slave station goes down, it is disconnected from regular polling, so the regular polling loop can be shortened, and if a slave station goes down, it sends common polling and sends a return response to the slave station that returns from down. The main station, which gives the station an opportunity to send, and receives this return response,
゛Since the slave station is reinserted into regular polling, the master station can automatically detect the return of the slave station, and no human intervention is required for the return process, which improves system reliability and facilitates automation. rate can also be increased.

[Brief explanation of the drawing]

Fig. 1 is a schematic block diagram of a system in which the invention is implemented, and Fig. 2 shows the system shown in Fig. 1. Polling time chart when all slave stations are normal. FIG. 6 is an example of a polling time chart in the system shown in FIG. 1 when some of the slave stations go down, and FIG. Time chart, FIG. 5 is a polling time chart after the slave station TS5 returns, and FIG. 6 is a time chart for explaining the processing operation when slave stations TS2 and TS5 return in the polling time chart example of FIG. 5. ,TSl・TS2−・−TSn
:Subordinate. Ll: Downward transmission line, L2: Upper transmission line. Patent Applicant Tateishi Electric Co., Ltd. Agent Patent Attorney Shigeru Nakamura Figure 1 q Figure 4 Figure 5

Claims (1)

[Claims] (1) Polling is performed from the master station to multiple slave stations. In a polling transmission method in which data is exchanged between a master station and a slave station upon receiving a response from the slave station. The master station sequentially sends regular polling containing individual addresses to each slave station, and if there is no response from each slave station, that slave station is marked as a down terminal and separated from the regular polling,
If there is a non-responsive slave station, following the regular polling, a common poll including the non-responsive slave station address to which the highest priority response order is attached is sent, and to the slave stations after the non-response slave station to which the highest priority response order is assigned. The response time after receiving the common polling is allocated in a time-division manner, and when each non-responsive slave station recovers from a down state and receives the 111 common total ring, it uses the slave station address included in this common polling and its own station address. When this transmission time is reached, a return response is sent to the main station when no other station has transmitted within mJ than the own station, and the main station that receives this return response A polling transmission system characterized in that the slave station that sent the return response is returned during the regular polling.