JP3399331B2 - Communication device and communication system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device and a communication system that perform communication asynchronously.

[0002]

2. Description of the Related Art Conventionally, for example, an on / off control signal from a control controller or the like is transmitted to an output device such as an air valve or an actuator of a machine tool or an input device such as a limit switch or various sensors. There is a communication system that transmits an on / off state signal to the control controller or the like. In such a communication system, in order to save wiring, a master station is connected to the control controller and a plurality of slave stations are connected to this master station. Connect stations,
An output device such as an actuator or an input device such as various sensors is connected to each slave station, and an on / off control signal transmitted from the control controller is output to the output device via the master station and the slave station, or There is a configuration in which an on / off state signal from an input device is taken into a slave station and transmitted to a control controller via a master station.

[0003]

In such a communication system, the master station calls each slave station in order and requests each slave station to transmit a status signal in order by the so-called polling selecting method. However, when each slave station senses the Busy flag indicating that it is communicating and is not communicating, it prepares for transmission by capturing the status signals of input devices such as various sensors. It sends the captured status signal in response to the call.

Therefore, when the status signal from the input device is taken in immediately before the transmission request from the master station, the status signal can be transmitted to the master station in the communication cycle, but immediately after the communication with the master station is completed. , When the status signal from the input device is fetched, the status signal is sent to the master station until the calling of the other slave station is finished and the corresponding slave station is called again, that is, until the next communication cycle is waited for. However, the response time between the minimum and the maximum varies, and therefore, in the conventional example, it was necessary to design the system in consideration of the maximum response time.

The present invention has been made in view of the above points, and it is an object of the present invention to suppress the variation in response time to the minimum side and enhance the responsiveness of the system.

[0006]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, the present invention of claim 1 is a communication system in which a plurality of slave stations are connected to a master station and the master station sequentially requests data transmission to each slave station, It detects that a transmission request has been made to a slave station which should be transmitted immediately before the slave station , and prepares for transmission of data to be transmitted to the master station.

The present invention according to claim 2 is directed to a plurality of communication devices.
Before connecting to the master station
It is a communication device, and a transmission request is made immediately before the communication device.
A send request was made to another communication device that should be done
Of the data to be transmitted to the master station.
It is for preparing.

[0009]

[0010]

[0011]

According to the communication system of the present invention of claim 1, the slave station should make a transmission request immediately before the slave station.
Detects that the transmission request to the slave station is performed, since the preparation for transmitting data to be transmitted to the master station, the child station
Just before sending a request for transmission to the
Ri, as in the conventional example that performs transmission by detecting that it is not in communication preparation, without such response time varies, it is possible to suppress the response time to a minimum side.

According to the communication device of the present invention of claim 2 ,
Another communication device to which a transmission request should be made immediately before the communication device.
When a transmission request is made to the
Since the data to be transmitted to the station is prepared for transmission,
Always prepare to send immediately before sending a request to the device.
And the response time varies as in the conventional example
It has never happened and the response time should be kept to the minimum.
You can

[0014]

[0015]

[0016]

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a communication system including a communication device according to the present invention.

This communication system comprises a control controller 1 and a master station 2 connected to the control controller 1.
And a plurality of slave stations 3 ₁ , 3 ₂ , 3 as a communication device according to the present invention, which are bus-connected to the master station 2 via a communication cable.
₃ ... and each slave station 3 ₁ , 3 ₂ , 3 ₃ ... is connected to an input device such as a proximity sensor or a limit switch, not shown, or to an output device such as a relay or an actuator. It

In this communication system, the master station 2 has each slave station 3
Communication is performed by a so-called polling selecting method, in which ₁ , 3, ₂ , 3 ₃ are called in order, and an on / off state signal from an input device is transmitted to each slave station 3 ₁ , 3 ₂ as in the conventional example. , 3 ₃ ... and the master station 2 to the control controller 1, and the control controller 1 takes in this status signal and performs arithmetic processing according to a preset program, and the on / off control signal is transmitted to the master station 2 Also, it outputs to the output device via each slave station 3 ₁ , 3 ₂ , 3 _3, ... To control the machine tool or the like.

As shown in FIG. 2, each slave station 3 ₁ , 3 ₂ , 3 _3, ... Is provided with a communication IC 4 including a transmission / reception circuit, a CPU 5 for controlling each section, and a status signal from an input device. Together with I / that outputs a control signal to the output device
And an O circuit 6.

In the conventional communication system, each slave station detects that it is not in communication, captures the status signal from the input device, prepares for transmission, and responds to the call from the master station with the status signal. Therefore, when the timing of preparation for transmission is varied and the status signal from the input device is captured immediately before the transmission request from the master station,
Although the status signal can be sent to the master station in the communication cycle, when the status signal from the input device is acquired immediately after the communication with the master station is completed, the call of the other station is completed and the corresponding slave station is called again. If you do not wait until the next communication cycle, the status signal cannot be sent to the master station,
Although the response time greatly varies, this embodiment is configured as follows so as to suppress the response time to the minimum side and eliminate the variation.

That is, in this embodiment, the master station 2
In advance each slave station 3 _1, 3 _2, 3 ₃ against ..., the slave station 3 _1, 3 _2, 3 ₃ ... station to be called just before, that is, the front station 2 _1, 3 ₂ Notify the address of…
Based on this address, each slave station 3 ₁ , 3 ₂ , 3 ₃ ...
It is detected that the front station 2, 3 ₁ , 3 ₂ ... has been called, and in response to this detection, the status signal from the input device is fetched to prepare for transmission, and the front station 2, 3 ₁ , 3 ₂ ... When the communication between the master station 2 and the master station 2 is completed and the slave stations 3 ₁ , 3 ₂ , 3 ₃ ... Are called, the status signal prepared immediately before transmission is transmitted to the master station 2.

As described above, when the preceding station 2, 3 ₁ , 3 ₂ ... Immediately before the slave station 3 ₁ , 3 ₂ , 3 ₃ ... Is called, the status signal from the input device is fetched and the transmission is prepared. That is, since the status signal is fetched and prepared for transmission immediately before the slave stations 3 ₁ , 3 ₂ , 3 ₃ ... Are called, the status signal can be transmitted in that communication cycle. In addition, there is no need to wait until the next communication cycle to transmit the status signal, and the response time can be suppressed to the minimum side.

FIG. 3 is a flow chart for explaining the operation on the master station side.

First, initial processing is performed (step n1),
After that, the communication network is initialized (step n).
2). In the initial processing of this communication network, each slave station 3
_1, 3 _2, 3 ₃ ... confirm whether a response to each, to create a scan table indicating the order of the call (transmission request) for each slave station 3 _1, 3 _2, 3 ₃ ..., each child Stations 3 ₁ , 3 ₂ , 3
₃ ... is notified of the addresses of the front stations 2, 3 ₁ , 3 ₂ ...

For example, the scan is performed in the order of the first slave station 3 _{1 with} the address " ₁ ", the second slave station 3 _{2 with} the address " ₂ ", the third slave station with the address "3", and so on. and the case, for example, the third slave station 3 ₃ of address "3", "2" the second slave station 3 _second address is a front station to be called just before the child station 3 ₃ notified, the slave station 3 ₂ second address "2", and notifies the address "1" of the first child station is a front station to be called just before the child station 3 _2. Further, in this embodiment, the first slave station 3 ₁ is notified of the address “0” of the master station 2 as the front station, and the master station 2 calls the master station itself as described later. When the line is checked, it is detected and ready for transmission. As another embodiment of the present invention, the first called slave station 3 ₁
Instead of the master station 2, it may detect that the last called slave station has been called and prepare for transmission.

After the above-described initial processing of the network is completed, communication is started, the master station itself checks the line (step n3), and according to the scan table, each slave station 3 ₁ , 3 ₂ , 3 ₃ ... To scan each slave station 3 ₁ , 3
₂ , 3 ₃ ... Communicating with the control signal and transmitting the control signal, while receiving the status signal (step n4), all the slave stations 3 ₁ , 3 ₂ ,
When the communication with 3 ₃ is completed, the received status signal is transmitted to the control controller 1 while the control controller 1 is transmitted.
The control signal is received from step n3 and the process returns to step n3 (step n5).

That is, the master station 2 has the slave stations 3 ₁ , 3 ₂ ,
Against 3 ₃ ..., except to notify the front station 2 _1, 3 ₂ ... address is the same as the basic operation of the conventional example.

FIG. 4 is a flow chart for explaining the operation on the slave station side.

First, initial processing is performed to recognize its own address (step n1), and then the communication network is initialized (step n2). In this communication network initial processing, a response from the master station 2 is answered. Then, the notification of the address of the immediately preceding station of the child station is received from the parent station 2.

Thereafter, the communication process is started (step n
3), when there is no call to your own station or the front station,
Performs application processing of its own station (step n4),
When there is a call to the previous station, which is the immediately preceding slave station, the status signal from the input device is set in the transmission buffer to prepare for transmission (step n5). While storing the data received from step 2 (step n6), the transmission data set in the transmission buffer is sent to the master station 2 (step n7), the control signal is extracted from the received data (step n8), and the extracted control signal Is set in the application buffer and is output to the output device (step n9).

Thus, in the slave stations 3 ₁ , 3 ₂ , 3 _3, ...
Detects that the front station 2, 3 ₁ , 3 ₂ ... which should be called immediately before the slave station 3 ₁ , 3 ₂ , 3 ₃ ... is called, captures a status signal from the input device, and prepares for transmission. When the slave stations 3 ₁ , 3 ₂ , 3 ₃ ... Are called, the status signal prepared for transmission immediately before that is transmitted.

When the number of slave stations is reduced or a new slave station is added and the address of the front station needs to be changed, the master station 2 creates a new scan table and creates a new scan table. notifies the address of the front station to the slave station 3 _1, 3 _2, 3 ₃ ..., slave station 3 _1, 3 _2, 3 ₃ ... is based on the newly notified address of the front station, near station called It is detected whether or not the operation is performed and the same operation as described above is performed.

[0035]

[0036]

As described above, according to the present invention, each slave station detects that the station to be called immediately before the slave station has been called and prepares for transmission. it is rather name that response time varies, Les Suponsu time can be minimized side, as in the prior art, it is not necessary to design the system in consideration of the maximum response time, to increase the responsiveness of the system You can

[Brief description of drawings]

FIG. 1 is a configuration diagram of a communication system including a communication device according to an embodiment of the present invention.

2 is a block diagram of the communication device of FIG. 1. FIG.

FIG. 3 is a flowchart for explaining the operation of the master station.

FIG. 4 is a flowchart for explaining the operation of the slave station.

[Explanation of symbols]

2 Master station 3 ₁ , 3 ₂ , 3 ₃ ... Slave station 4 Communication IC 5 CPU 6 I / O circuit

Claims (2)

(57) [Claims] 1. In a communication system in which a plurality of slave stations are connected to a master station and the master station sequentially requests each slave station to transmit data, the slave station transmits immediately before the slave station. Request should be made
A communication system, which detects that a transmission request is made to a slave station and prepares for transmission of data to be transmitted to the master station. 2. Data is sequentially transmitted to a plurality of communication devices.
The communication device connected to the master station that requests transmission
Te, other communication to the transmission request is made immediately before the communication device
Detecting that a transmission request was made to the device,
Characterized by preparing to send data to be sent to the master station
Communication device.