JPH0832604A - Polling method for multi-drop connection data communication system - Google Patents

Abstract

PURPOSE:To permit a master station only to once transmit a synchronizing signal and a command so as to collect data of all slave stations by permitting the master station to put all ID of the slave stations whose data are to be collected in the command transmitted by polling in the order of data collection. CONSTITUTION:A data communication system consists of the master station M and the plural slave stations S1-S3, which are connected to a common communication line in a multi-drop form, and the master station M collects data of all the slave stations S1-S3 by polling. A period from time when the master station M once transmits at least a data communication request CMD to all the slave stations S1-S3 to time when the respective slave stations S1-S3 sequentially finish transmitting at least self station data D1-D3 consisting of the generated data of the self stations and station numbers is set to be the one cycle of data collection. Since data for n-stations can be collected by one synchronizing signal SYN and one command CMD, communication time required for collecting data for n-stations can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses, for example, one of a plurality of vending machines as a master station (also called a main station) and the other as slave stations, and connects these stations to a dedicated communication line in a multi-drop manner. In a data communication system in which a master station polls a slave station for data such as sales generated by each station, the present invention relates to a polling method capable of shortening the data collection time.

In the following drawings, the same reference numerals indicate the same or corresponding parts.

[0003]

2. Description of the Related Art FIG. 6 shows an example of the configuration of a data communication system of this kind of multi-drop connection. This system is a master station M that manages the entire system on a dedicated communication line L common to each station.
And the slave stations S (S1, S2, S3 ...) Are connected. FIG. 5 shows a command CMD transmitted by the master station M in the conventional polling in the data communication system as shown in FIG.
A configuration example of is shown. In FIG. 5, 1 is prefix data (CMD data) indicating that the signal of FIG. 5 is a polling command CMD, and 2 is I for designating a slave station S of a transmission destination.
D and 3 are the number of blocks of this polling data.

FIG. 4 shows a conventional polling communication sequence in the system of FIG. That is, all the slave stations S1 to S3 wait for reception by the synchronization signal (SYN signal) of the solid arrow transmitted by the master station M, and the command (CMD) of the dotted arrow transmitted by the master station M next is transmitted to all the slave stations. Station S receives. The slave station checks the contents of the command CMD as shown in FIG. 5, and if the transmission destination ID2 is addressed to itself, transmits the data to the master station M as indicated by the one-dot chain line arrow. If it is not addressed to itself, it does not transmit data and waits for the next synchronization signal.

When the data communication for one station is completed by the above series of communications and there are n slave stations, this communication is repeated for the number of n stations.

[0006]

However, in the data collecting method as described above, the master station collects the data for one slave station by issuing the sync signal and the command each time and collecting them. In addition, there was a problem that it took too much time to collect data for the entire system. Therefore, it is an object of the present invention to provide a polling method for a multi-drop connection data communication system that can solve this problem.

[0007]

In order to solve the above-mentioned problems, in the polling method according to claim 1, a master station (such as M) connected in a multi-drop manner to a common communication line (such as a dedicated communication line L). And multiple slave stations (S1 to S3, etc.),
In a data communication system in which the master station collects data of all slave stations by polling, after the master station at least once transmits a data transmission request (command CMD, etc.) to all slave stations, each slave station responds to the request. In order, the local station data (D1 to D3) including at least the local station generated data and station number
Etc.) is sent to the master station until the end of one cycle of data collection.

Further, in the polling method according to the second aspect, in the polling method according to the first aspect, the order of data transmission to the master station is preset in the slave station. Further, in the polling method according to claim 3, in the polling method according to claim 1, the order of data transmission of the slave station is added to the data transmission request transmitted by the master station (slave station ID 2-1 of data acquisition target). ~, 2-n, etc.).

Further, in the polling method according to claim 4, in the polling method according to any one of claims 1 to 3, the slave station transmits the self station data to be transmitted to the master station in the data collection cycle. It should be transmitted to other slave stations of transmission.

[0010]

In the present invention, when there are n slave stations, the master station conventionally issues n sync signals and commands to collect data. Minute data can be collected to shorten the communication time required to collect data for n stations.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 3 shows a configuration example of the command CMD transmitted by the master station in the polling of the present invention. The same figure is shown in FIG.
On the other hand, the transmission destination ID2 that has designated only one slave station is ID2-1, ..., 2- that designates all slave stations in the transmission order.
The number 4 (in this example, the value “n”) of the slave stations that are to be replaced with n and want to acquire data is added.

However, if the order of transmission is set in advance for each slave station, the meaning of the CMD data 1 is replaced with "request for data transmission to all slave stations", so that each slave station ID 2-1 and
~, 2-n can be omitted. FIG. 1 shows a polling time chart of the present invention in the data communication system of FIG. 6, and FIG. 2 also shows a polling communication sequence. Next, the flow of polling according to the present invention will be described with reference to FIGS. First, as in the conventional case, the master station M transmits a synchronization signal (SYN), and all the slave stations S (S1 to S) are transmitted.
3) is turned to the master station M, and then the command CMD in FIG.
Send All slave stations S1 to S3 use this command CM
D is received and stored in the memory of its own station, and the master station M
Recognize the order of sending data to.

In this example, the case where the order of transmission to the master station M is as follows will be described. Slave station ID that first obtains data (2-1 in FIG. 3):
Slave station S1 Slave station ID that obtains the second data (2-2 in FIG. 3):
Slave station S2 Slave station ID for third data acquisition (2-n in FIG. 3, where n = 3): Slave station S3 Corresponds to “slave station ID for first data acquisition” of the command CMD. Upon reception of the command CMD, the slave station S1 transfers its own data D1 to the master station M and the slave station S2.
Send to S3. Then, the slave station S1 waits for the next synchronization signal SYN.

The slave station S2 corresponding to the "second slave station ID for acquiring data" of the contents of the command CMD is the data D
As soon as the reception of 1 is completed, the data D2 of its own station is transmitted to the master station M and the slave station S3. Then, the slave station S2 waits for the next synchronization signal SYN. The slave station S3 corresponding to the “third slave station ID for acquiring data” in the content of the command CMD receives the data D of its own station as soon as the reception of the data D2 is completed.
3 is transmitted to the master station M. Then, the slave station S3 waits for the next synchronization signal SYN.

When the master station M finishes receiving the data D3 from the slave station S3, it recognizes that a series of polling (that is, one polling cycle) is finished and performs polling for the next cycle. repeat.

[0016]

According to the present invention, since all the IDs of the slave stations for which data collection is desired are put in the command CMD transmitted by the master station in polling, in the order of data collection, the master station is The data of all the slave stations can be collected only by transmitting the synchronization signal and the command for the number of times.

As described above, according to the present invention, the effect that data can be collected in the shortest time can be obtained.

[Brief description of drawings]

FIG. 1 is a time chart of polling according to an embodiment of the present invention.

FIG. 2 is a diagram showing a communication sequence corresponding to FIG.

FIG. 3 is a block diagram of a polling command as an embodiment of the present invention.

FIG. 4 is a diagram showing a conventional communication sequence corresponding to FIG.

FIG. 5 is a diagram showing a configuration example of a conventional polling command.

FIG. 6 is a diagram showing a configuration example of a multi-drop connection data communication system.

[Explanation of symbols]

 M Master station S (S1 to S3) Slave station L Dedicated communication line SYN Sync signal CMD command D1 Transmit data of slave station S1 D2 Transmit data of slave station S2 D3 Transmit data of slave station 1 CMD data 2-1 First Station ID that acquires data 2-2 Station ID that acquires data second 2-n Station ID that acquires data second n 3 Number of polling data blocks 4 Number of stations that want to acquire data

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Sugino 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd.

Claims (4)

[Claims] 1. A data communication system comprising a master station and a plurality of slave stations connected to a common communication line in a multi-drop manner, wherein the master station collects data of all slave stations by polling. After sending a transmission request to all slave stations once, each slave station collects data in response to this, at least until it finishes transmitting its own station data consisting of its own station data and station number to the master station. The method for polling a multi-drop connection data communication system is characterized in that 2. The polling method according to claim 1, wherein the order of data transmission to the master station is preset in the slave station. 3. The multi-drop connection data communication system according to claim 1, wherein the data transmission request transmitted from the master station is added with the order of data transmission from the slave station. Polling method. 4. The polling method according to claim 1, wherein the slave station transmits the local station data to be transmitted to the master station to other slave stations which have not yet transmitted the data within the relevant data collection cycle. A polling method for a multi-drop connection data communication system, characterized in that the data is transmitted.