JPH01261038A - Polling system - Google Patents

Abstract

PURPOSE:To efficiently receive a terminal data by allowing a terminal equipment sending the last data to set flag and allowing a terminal equipment having a set flag to reset a counter when the counter receives the prescribed value of polling signal sent from a controller. CONSTITUTION:Number of terminal equipments sending once a data in a system is determined to k-set less than all terminal number (n), a polling signal counter is provided and a flag F is provided to each terminal equipment. The counter counts a terminal equipment number sending a data and each terminal equipment sends the data when the number of counters is A prescribed number (k) or below. The flag F is used to allow the terminal equipment to recognize that the data is sent in the k-th order, and a terminal equipment whose flag F is set has a right to reset the count of a polling signal of the counter (k) to zero. Thus, lots of terminal equipments not normally having transmission data can collect data with a few number of buffers efficiently uniformly to each terminal equipment.

Description

[Detailed Description of the Invention] [Summary of the Invention] An object of the present invention is to efficiently receive terminal data using a small-capacity reception buffer regarding a polling method in a system in which a control device sucks data from a plurality of terminal devices by polling. The control device and multiple terminal devices are connected in a loop, the polling signal from the control device is passed between the terminal devices, and data from multiple terminal devices is sent to the control device with one polling. In the siphoning system, a counter indicating the number of terminal devices that have transmitted data is provided in the polling signal, and when the counter is below a predetermined value, the terminal device is enabled to transmit data, and when the data is transmitted, the counter is incremented. In addition, a flag is provided in the terminal device, and the terminal device that transmitted the last data sets the flag, and when the counter sent from the control device receives the polling signal of the predetermined value, the flag is set. Terminal equipment with the flag is configured to reset the counter.

[Industrial application field]

The present invention relates to a polling method in a system in which a control device collects data from a plurality of terminal devices by polling.

[Conventional technology]

As shown in FIG. 1, a control device 10 and a plurality of 11° 12,
There is a system in which ...... are connected in a loop.

The connection device 10 sends a polling signal to the terminal device 11 through the line β0, and in response to this, the terminal device 11 sends data to the control device 10 through the line 1a, and transfers the polling signal to the terminal device 12 through the line l; . When receiving a polling signal from the terminal device 11, the terminal device 12 sends it to the control device 10 through the data line βb, the terminal 11, and the line βa, and also transfers the polling signal to the terminal device 13 through the line 12. The same applies below. Last terminal device I
At N, the polling signal is sent to the data control device, and the polling signal is returned to the control device through the line βn, thus completing one cycle. After one cycle is completed, the control device processes the data accumulated in the buffer from the terminal devices 11 to IN.

[Problem to be solved by the invention]

In this way, when a control device and multiple terminal devices are connected in a loop, and the polling signal from the connected device is passed to the adjacent terminal one after another, and data from all terminals is collected in one poll, the data from each terminal is data up to m bytes,
Assuming that the number of terminals is n, the control device needs to prepare a reception buffer of mXn bytes. This is fine in a system where each terminal always generates data, but in a system where the probability that all terminals generate data at the same time is low, it is a waste of memory to prepare a receive buffer of m x n bytes.

It is an object of the present invention to improve these points and to enable terminal data to be efficiently received with a small-capacity reception buffer.

[Means to solve the problem]

In the present invention, the number of terminals that transmit data at one time in the system is set to be less than the total number of terminals n.

Further, a polling signal counter 21 is provided as shown in FIG. 2, and a flag F is provided at each terminal as shown in FIG. The counter 21 counts the number of terminals that have transmitted data, and each terminal is enabled to transmit data when the counter is equal to or less than a predetermined number. Flag F is for the terminal to recognize that data has been transmitted in the second (last cycle of the cycle), and the terminal with this flag F set receives the polling signal sent from the control device to the counter. has the right to reset the counter to zero.

In addition, in Fig. 2 (al indicates the format of the polling signal, and there is an ENQ and counter 21 between STX and ETX. has a UA (unit address; terminal ID) and transmission data 22. Of course, S T X is a start option text, ETX is an end of text, and ENQ is an enquire.

[Effect]

In this polling method, the control device 10 first sends a polling signal with the counter 21 set to 0 to the terminal 11. The terminal 11 checks the counter and if it is below, and if there is data to be transmitted, it sends the data to the control device 10, and after transmitting the data, it increments the counter by 1 and sends a polling signal to the next stage.

The next stage similarly checks the counter, and if it is less than k and there is data to be transmitted, the data is sent to the control device, and when the data is transmitted, the counter is incremented by 1 and a polling signal is sent to the next stage. The same applies below. Final terminal IN
If the counter value does not reach k, all terminals that have sent data send out data, and the polling cycle ends.

When the counter value reaches k at a certain terminal, the terminal sets flag F to 1. The next terminal receives a polling signal from the counter, and in this state, data transmission is not possible, and the polling signal from the counter is simply transferred to the next stage. The same applies below. At the final terminal, a polling signal of the counter is returned to the control device.

Upon receiving this, the control device directly sends a counter polling signal to the terminal 11.

Since the terminal 11 is a counter, it does not transmit data, but simply transfers the polling signal to the next stage.

A polling signal for the counter is sent to the terminal whose flag F is 1 (then the terminal resets the counter to O and transfers the polling signal of the counter 0 to the next stage. Since the counter is 0, if there is data to be transmitted, the data is sent to the control device, and when the data is transmitted, the counter is incremented by 1 and a polling signal is sent to the next stage.

The same goes for the rest, and in this way data transmission is started from the terminal that could not send data in the first polling.

In this manner, the polling method of the present invention allows data to be collected uniformly from a large number of terminals that do not always have data to transmit, efficiently and with a small buffer.

(Example) The processing in the control device is shown in FIG. 3, and the processing in the terminal device is shown in FIG. 4.As shown in FIG. ■ Send
. As a result, a signal (either data or polling signal, but initially data) is sent from the terminal, so it is received ■, and until the polling signal is sent from the final terminal (■ is YES) data Continue receiving. When a polling signal is sent from the final terminal, the counter value is checked and if the counter value is not k (■ is NO).
), set the counter to 0, and send a polling signal at the next polling cycle. If the counter value is k (■ is Y
ES), do not set the counter to 0, leave it at that value, and send a polling signal at the next polling cycle■.

As shown in Fig. 4, when the terminal device receives a polling signal, it checks the counter value.If it is not k, it checks whether there is data to be transmitted at its own terminal.If so, it sends it and returns it to the counter. +1■, In this state, look at the counter again and check whether it is k or not■, If it is not k, send a polling signal to the next terminal device, if it is k, set the flag of the own terminal to 1, and then proceed to the next terminal device. Send a polling signal to the terminal.

In the first count check (2), if the counter value is k, the flag of the own terminal is checked (3), and if it is not l, the polling signal is transferred to the next terminal device. Therefore, when the counter reaches k at a certain terminal, subsequent terminals simply transfer the polling signal without transmitting data, and the final terminal returns the polling signal to the control device with the counter =. When this is received, the control signal sends the polling signal of the counter to the terminal side as described above.

When the first terminal device (closest to the control device) receives this, the counter is on, so it moves to (2), and since the flag of its own terminal is not 1, it simply transfers the polling signal to the next stage. No data is sent. Counter k on own terminal
When the polling signal is transferred to the terminal that has become
■Flag -1? Since the result is YES, the polling signal counter (currently k) is reset to 0 (2), the flag of the own terminal is also reset to O (2), and the polling signal with the counter = 0 is transferred to the next terminal. The terminal now has counter = 0
Therefore, data transmission, counter +1, and polling signal transfer are performed by following the route (■, ■, ■, etc.). The same goes for the next terminal after the next terminal.

Flag = 1 indicates that the terminal was the final terminal for data transmission, and the final terminal has the right to reset the polling signal counter = k to 0.

According to this method, even if there are a large number of terminals, as long as the number of terminals that have data to send at each point in the polling cycle is within That's enough. If transmission data happens to occur at the same time in a large number of terminals, data will be collected by multiple pollings, but unless terminal data is generated continuously, there will be no data overflow at the terminals.

〔Effect of the invention〕

As explained above, according to the present invention, the size of the reception buffer can be reduced. For example, the number of terminals is 100
Assuming that the maximum length of data is IK bytes, the conventional method required a 100K byte buffer.
IO by limiting the number of terminals that send data at one time to 10
K bytes, and all terminals can receive the same service.

[Brief explanation of the drawing]

Fig. 1 is a block diagram explaining the configuration of the polling system, Fig. 2 is an explanatory diagram of the signal formant, Fig. 3 is a flowchart showing the operation of the control device, and Fig. 4 is a flowchart showing the operation of the terminal device. be. In FIGS. 1 and 2, 10 is a control device, 11 to IN are terminal devices, 1aylln, la, . . . are signal lines, F is a flag, and 21 is a counter.

Claims (1)

[Claims] 1. A control device (10) and a plurality of terminal devices (11, 12)
,...) are connected in a loop, and polling signals from the control device are passed between the terminal devices, and data from multiple terminal devices is sucked up to the control device with one polling. A counter indicating the number of terminal devices that transmitted data is provided in the polling signal,
When the counter is below a predetermined value, the terminal device is enabled to transmit data, and when data is transmitted, the counter is incremented, and a flag (F) is set in the terminal device, indicating that the terminal device that transmitted the last data is eligible for data transmission. A polling method characterized in that a flag is set, and when the counter sent from a control device receives a polling signal of the predetermined value, a terminal device having the set flag resets the counter.