JPH0217741A - Data communication system - Google Patents

Abstract

PURPOSE:To perform communication among slave stations mutually without interposing a control station even under communication control of polling/ selecting system by attaching two addresses on every piece of data transferred among the stations. CONSTITUTION:The control station 2 sets the address of a targeted slave station 3i on the address A1, and sets the address of its own station on the address A2, then, performs polling. The slave station 3i, when receiving data whose address A1 coincides with the address of its own station, recognizes that the polling is the one from the control station 2. At this time, the slave station 3i issues a response by setting the address of another slave station 3m that is an opponent on the address A2 when transmission data to be transmitted to the slave station 3m exists. In such a way, since the control station M continues the polling as holding a state of present data link, the slave station 3i can communicate with the slave station 3m.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a polling/selenting system in which a single control station and a plurality of dependent stations perform bidirectional data communication via a common transmission path. The present invention relates to a data communication method used in a communication system of the above-mentioned method.

(Prior Art) Conventionally, in a data communication system, there is a polling/selecting method as one of the methods for connecting a plurality of stations to a common transmission path and performing bidirectional data communication.

This system defines one station as a control station and all other stations as dependent stations. The control station specifies one dependent station and transmits data, and either receives data from that dependent station, or sends data to other dependent stations after a timeout, so-called control station initiative. This is a type of data communication method.

(Problem to be Solved by the Invention) In the data communication method described above, when communication is to be carried out between subordinate stations, it must be relayed by the control station each time, and communication cannot be carried out directly. . Therefore, there was a problem of poor transmission efficiency in communication between dependent stations.

The present invention has been made in view of the above circumstances, and is based on polling/
Under communication control using the selenting method, it is possible to communicate between dependent stations without going through a control station.This allows communication between dependent stations to be carried out efficiently.
The purpose is to provide a data communication method that can improve transmission efficiency.

[Structure of the Invention] (Means and Effects for Solving the Problems) The present invention assigns unique addresses to each of a control station and a dependent station. Further, by adding two addresses (address 1 and address 2) to each data transmitted and received between stations, data link setting between dependent stations is realized.

With this configuration, it is possible to set up independent data links between dependent stations while maintaining the data link between the control station and dependent stations under communication control using the polling/selenting method. . Further, by using the response to polling from the control station as data to be transmitted to other dependent stations, it is possible to improve transmission efficiency (Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a system configuration according to an embodiment of the present invention.

In FIG. 1, ``■'' is a transmission line, and a single control station and a plurality of dependent stations are connected. 2 is a control station (M), of which only one exists on the same transmission path l. 3a, 3b,・
..., 3n are dependent stations (S), and a plurality (n) of them exist on the same transmission path 1.

A control station 2 and a plurality of dependent stations 8a and 3b on a transmission path l.

... 3n performs bidirectional data communication, but here, when transmitting data, each station uses two addresses (address 1 and address 2) Al for each unit of transmitted data.
, A2, and at the time of reception, the above two addresses (address 1, address 2)
AI recognizes the source and destination stations from A2, and sends control station (M) 2 and dependent station (S) according to the specified address contents.
) 31 (one of i-1, 2°..., n)
, or has a receiving function for exchanging data between dependent stations. That is, each dependent station (S) 3a, 3b, -, 3n
At the time of reception, when address 1 (Al) is the local station address, if there is no data to be sent to other dependent stations,
It performs a data link operation with the control station (M) 2, sets its own address in address 1 (A1), sets the control station address in address 2 (A2), and performs data transmission. or,
Address 1 (Al) is not your own address, but address 2
When (A2) is the local address, address 1 (Al
) performs data link operations with dependent stations. On the other hand, control station (M) 2 sets the dependent station address in address 1 (AI) and its own station address in address 2 (A2), and transmits data.
When (A2) is the local address, address 1 (AI
), and if address 2 (A2) is not its own address, it begins preparations for polling the next dependent station.

In this way, the control station (M) 2 and the dependent station (S) 3a.

3b,..., 3n each have two addresses (
Address 1. Address 2) Transmission function that adds Al and A2 and the above two addresses (Address 1. Address 2)
AI recognizes the source and destination stations from A2, and sends control station (M) 2 and dependent station (S) according to the specified address contents.
) 31 (1-1, 2, = -, n) or a receiving function for exchanging data between dependent stations.

FIG. 2(a) is a flowchart showing the operation processing flow of the control station (M) 2 in FIG. 1, and FIG. 2(b) is a flowchart showing each dependent station (S) 3a also in FIG. 1.

3b, . . . , 3n is a flowchart showing the operation processing flow.

In FIG. 2(a), step Sl, 82 is a step of polling the dependent station (S) 31, and the dependent station address is set as address 1 (AI), and address 2 (
As A2), the own station address is added and the data is transmitted. Steps 83 to S5 are steps for receiving a response from the dependent station (S) 31, and at this time address 2 (A2)
does not match the own station address, the dependent station (S) 3
The data link status with 1 is suspended. Step SB is a step for preparing for polling the next dependent station (S) 3j.

Also, in FIG. 2(b), step S12°S13
．． S19 is a step of analyzing the received address 1 (At), and when address 1 (At) matches the local station address, it is determined that the polling is from the control station, and address 2 (A2) is the local station address. When the data matches the data, it is determined that the data is from another dependent station. Step S15
．． S1B is a step for responding to polling, and transmits data by adding the local station address as address 1 (At) and the control station address as address 2 (A2). Steps S17 and 818 are steps for transmitting data to other dependent stations, and address 1 (AI
) and the other party's dependent station address as address 2 (A2), and transmit the data. This data also serves as a response to the control station (M)2.

The operation of an embodiment of the present invention will now be described with reference to FIGS. 1 and 2.

The control station (M) 2 sets the address of the target dependent station (S) 31 in the address 1 (At), and sets the address of the target dependent station (S) 31 in the address 1 (At).
2) Set the address of your own station and perform polling (
FIG. 2 Step SL, S2).

When the dependent station (S) 31 receives data whose address 1 (At) matches its own address, it transmits the data to the control station (M).
It is recognized that the bowling is from 2 (step 512 in FIG. 2).

At the time when the dependent station (S) 31 receives the polling, the dependent station (S) 31 performs the following operations on the other dependent stations (S) 3a, 3b, -=, 31-1.3
1+1. --- If there is no data to send to 3n, address 1 (Al) is the own station address, address 2 (A2
) and returns a response (steps S13 to S1B in FIG. 2).

Also, other dependent stations (S) 3a, 3b, -, 31-1,
31+1゜... If there is data to be sent for the 3rd day, the address 1 (AI) is the own station address, and the address 2 (AI) is the own station address.
A2) sets the address of the other party's dependent station (for example, 301) and responds. The content of the transmission data at this time is assumed to be for the other party dependent station (S) 3m+ (step S17.518 in FIG. 2).

This data is received by the control station (M) 2 as a response to the previous polling, and is simultaneously received by the other dependent station (S) 3m indicated by address 2 (A2).

If the address 2 (A2) of the received response belongs to the control station (M) 2, it performs an operation according to the data link procedure with the dependent station, and if the address 2 (A2) is not the own station. If so, continue polling while suspending the current data link status (step 8 in Figure 2).
3-S5).

In addition to the polling from the control station (M) 2, the dependent station (S) 31 receives data whose address 2 (A2) matches its own station address, and sends this data to the address indicated by address 1 (At). It is recognized that the data is from a dependent station (step 519 in FIG. 2). If it is necessary to respond to this data, the response is made upon receiving the polling from the control station (M) 2 (step S17 in FIG. 2).
S1g).

In this way, the control station (M) 2 and the dependent station (S) 3a.

3b,... 3n are each address 1 at the time of transmission.
(Al) and address 2 (A2) are added, and when receiving, the above address 1 (Al) and address 2 (
The source and destination stations are recognized from the two addresses in A2), and the control station (M) 2 and dependent station (S) 31 . Or exchange data between dependent stations. As a result, under communication control using the polling/selecting method, independent data links can be established between dependent stations while maintaining data links between the control station and dependent stations, and polling from the control station The transmission efficiency can be greatly improved because the response to the request and the data to be transmitted to other dependent stations can be shared.

[Effects of the Invention] As detailed above, according to the data communication system of the present invention,
In a polling/selecting communication system in which a single control station and multiple subordinate stations perform bidirectional data communication via a common transmission path, each station has a means for adding two addresses at the time of transmission. The dependent station has means for determining each of the addresses at the time of reception, and when one predetermined address is its own address, performs a data link operation with the dependent station indicated by the other address. With this configuration, independent data links can be established between the dependent stations while maintaining the data link between the control station and the dependent stations. Furthermore, the control station determines each of the addresses at the time of reception, and when one predetermined address is its own address, it performs a data link operation with the dependent station indicated by the other address, and when the one address is By having a configuration that includes means for continuing polling to the next dependent station when the address is not the own station address, it is possible to use the response to polling from the control station as data to be sent to other dependent stations.

As a result, transmission efficiency can be greatly improved in a polling/selecting type communication system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the system configuration in one embodiment of the present invention, FIG. 2(a) is a flowchart showing the operation processing flow of the control station in the above embodiment, and FIG. It is a flowchart which shows the operation processing flow of the dependent station in an Example. l...Transmission path, 2...Control station (M), 3a, 8
b,...3n...Subordinate station (S) Al...Address 1, A2...Address 2゜Applicant's agent Patent attorney Takehiko Suzue

Claims (3)

[Claims] (1) In a polling/selecting type communication system in which a single control station and multiple subordinate stations perform bidirectional data communication via a common transmission path, two addresses are added to each station at the time of transmission. The dependent station has means for determining each of the addresses at the time of reception and performing a data link operation with the dependent station indicated by the other address when one predetermined address is its own address. A data communication method characterized by: (2) In a polling/selecting communication system in which a single control station and multiple dependent stations perform bidirectional data communication via a common transmission path, two addresses are added to each station at the time of transmission. The dependent station has a means for determining each address at the time of reception, and when one predetermined address is its own address, performs a data link operation with the dependent station indicated by the other address, and A data communication system comprising means for performing a data link operation with the control station when the other address is the own address. (3) In a polling/selecting communication system in which a single control station and multiple dependent stations perform bidirectional data communication via a common transmission path, two addresses are added to each station at the time of transmission. The control station has a means for determining each of the addresses at the time of reception, and when one predetermined address is its own address, performs a data link operation with a dependent station indicated by the other address, and When one address is not the own address, the slave station has a means for preparing to poll the next dependent station, and the dependent station determines each address at the time of reception, and when one address is the own address, the other 1. A data communication system comprising means for performing a data link operation with a dependent station indicated by an address.