JPH09284313A - Serial communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the scale of a whole device even when plural driver/ receivers are used in a serial communication system. SOLUTION: A computer circuit 1 reports the poling address of an opposite device, for example, 6-1 to a driver/receiver managing means 3. Only the driver/ receiver 2-1 connected to the opposite device 6-1 is turned on in the driver/ receiver managing means 3. The computer circuit 1 transmits transmission data to SCU(serial communication processor). SCUa 5 transmits transmitted transmission data to the driver/receivers 2-1 to 2-3. Only the driver/receiver 2-1 which is turned on transmits serial communication data to the opposite device 6-1 with a communication line. Only the opposite device 6-1 executes answer-back.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial communication system, and more particularly to a multipoint connection serial communication system.

[0002]

2. Description of the Related Art A conventional center-side device (primary station) (supervisory control device) uses a polling selective method for designating communication timings with a plurality of partner devices (secondary stations), and uses a multipoint connection serial line. The communication system is shown in FIG.
The configuration is as shown in.

In FIG. 3, a computer circuit 1, a serial communication processing unit (hereinafter referred to as SCU (Serial Con)
5-1 to 3), the selection circuit 7, and the drivers / receivers 2-1 to 3 constitute a center device (primary station), and a partner device (secondary station) 6 via a serial communication line. Connect to -1 to 3.

The computer circuit 1 determines which SCU 5-1 to 3 is connected to the partner device to which the data is to be transmitted, for example, 6-1 by the (polling) address of the partner device 6-1 and the selection circuit. SC applicable by 7
Select U5-1 and send the transmit data to that SCU5-1.

The SCU 5-1 converts the transmitted transmission data into serial communication data according to a communication procedure (protocol) and transmits it to the driver / receiver 2-1. driver/
The receiver 2-1 converts the sent serial communication data into serial communication data of the standard designated by the communication line, and transmits the serial communication data to the partner device 6-1 via the communication line.

If there is an answer back from the partner device 6-1, the driver / receiver 2-1 converts it into serial communication data that can be received by the SCU 5-1 and sends it to the SCU 5-1. The SCU 5-1 sends the received data. , The data is converted into data that can be received by the computer circuit 1 and temporarily stored.
At the same time, the computer circuit 1 is notified that the data has been received. The computer circuit 1 is SC through the selection circuit 7.
U5-1 is selected, the reception data temporarily stored in the SCU 5-1 is read, and the communication process for one partner device 6-1 is completed.

[0007]

In the case of the conventional example shown in FIG. 3, the driver / receivers 2-1 to 2-1 and the partner device 6-1 to 6-1 are connected.
3 are connected to each other one-to-one, but one driver / receiver is connected by multipoint connection, for example, Japanese Patent Laid-Open No.
It is also possible to connect to a plurality of partners as described in Japanese Patent Publication No. 78096. However, for example, when there is a unavoidable plural communication lines depending on the partner device, the driver / receiver and the SCU must also be plural.

When there are a plurality of SCUs, the scale of the control circuit for data input / output with the computer circuit tends to increase,
The increase in the number of SCUs is disadvantageous in terms of device miniaturization and cost.

It is an object of the present invention to provide a serial communication system in which the size of the entire device is minimized even if there are a plurality of drivers / receivers.

[0010]

A serial communication system for communicating with a plurality of partner devices according to the present invention in a polling selective system is a computer circuit which sends out transmission data and controls the entire device, and the transmission data is converted into serial communication data. A serial communication processing device for converting,
A switch for selecting and activating a plurality of drivers / receivers for transmitting the serial communication data to a partner device through a communication line and the driver / receiver to which the partner device to which the transmission data is to be transmitted are connected through a communication line And a control means.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of the present invention is as follows.
Even if a plurality of drivers / receivers are provided, a single SCU is commonly used instead of a plurality of SCUs, and a plurality of drivers / receivers are switched and used by using a switching control circuit.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a serial communication system according to the present invention, and the same parts as those in FIG. 3 are designated by the same reference numerals. In addition, overlapping description is omitted.

Also in FIG. 1, the driver / receiver 2-1 is used.
3 to 3 and the partner devices 6-1 to 6-3 are drawn so as to be connected one-to-one, but this is drawn for convenience in order to avoid complicating the drawing, and as described above. One driver / receiver can be connected to a plurality of partner devices by multipoint connection.

In FIG. 1, the computer circuit 1 for managing the communication process notifies the driver / receiver managing means 3 of the polling address of the partner device, for example, 6-1 and starts it when starting the communication.

Activated driver / receiver management means 3
2, the polling address input means 3-1 reads the polling address, as shown in FIG. Next, in the corresponding driver / receiver judging means 3-2, refer to the preset parameter for which driver / receiver 2-1 to 3 the partner device of the polling address, for example, 6-1 is connected. And judge.

In the driver / receiver control means 3-3,
Driver / receiver 2 to which partner device 6-1 is connected
Only -1 is turned on and other drivers / receivers 2-2
.About.3 instructs the computer circuit 1 to turn off.

The switching control circuit 4 controls the drivers / receivers 2-1 to 2-1 to 3 according to an instruction from the computer circuit 1. The computer circuit 1 sends the transmission data to the SCU 5 when the operation of the driver / receiver management means 3 is completed. The SCU 5 converts the transmitted transmission data into serial communication data according to the communication procedure (protocol), and transmits the serial communication data to the driver / receivers 2-1 to 2-1.

Therefore, only the driver / receiver 2-1 which is turned on converts the transmitted serial communication data into serial communication data of the standard specified by the communication line, and the partner device 6 is connected via the communication line. Send to -1.

In case of multi-point connection,
Among the devices connected to the same serial communication line, only the partner device whose polling address and the device address match, for example, 6-1 performs prescribed processing based on the received data and returns the answer back. The driver / receiver in the ON state receives the answer back data, converts the data format, and returns it to the SCU 5.

Also in the conventional serial communication apparatus shown in FIG. 3, in the case of the polling selective method, communication is performed by calling the partner device (secondary station) from the computer circuit (primary station) side (from the partner device). Since it does not call the computer circuit side), multiple SCUs do not operate simultaneously. Therefore, in the embodiment of the present invention shown in FIG. 1, even if there is only one SCU, there is no problem in this respect.

[0022]

As described above, according to the present invention, even when a plurality of drivers / receivers are required, only one SCU is required, the connection circuit between the computer circuit and the SCU becomes simple, and a plurality of SCUs are not required. Together, there is an effect that it is advantageous in terms of size reduction and cost of the device.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing details of driver / receiver management means.

FIG. 3 is a block diagram showing an example of a conventional serial communication system.

[Explanation of symbols]

 1 Computer Circuit 2-1 to 3 Driver / Receiver 3 Driver / Receiver Management Means 4 Switching Control Circuit 5 SCU 6-1 to 3 Other Device

Claims (3)

[Claims] 1. A serial communication system for communicating with a plurality of partner devices in a polling selective system, a computer circuit for sending out transmission data and controlling the entire device, and a serial communication process for converting the transmission data into serial communication data. A device, a plurality of drivers / receivers for transmitting the serial communication data to a partner device through a communication line, and a driver / receiver in which the partner device to which the transmission data is to be delivered is connected through a communication line
A serial communication system comprising a switching control means for selecting and activating a receiver. 2. The apparatus further comprises means for delivering received data, which is answered back from the partner device, to the computer circuit through the activated driver / receiver and the serial communication processing device. The serial communication system according to item 1. 3. The switching control means selects and activates the driver / receiver based on a polling address of the partner device.
The described serial communication system.