JPH1198215A - Serial transmission method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable communication in different communication device standards, and to simplify a hardware configuration therefor. SOLUTION: Drivers 6 and 7 can be exchangeably connected to a connector 5. The type of the installed driver 6 is CPU
12, the corresponding communication software is automatically selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to RS232C, R
The present invention relates to a serial transmission method suitable for a communication device that selectively uses a plurality of communication standards such as S485.

[0002]

2. Description of the Related Art In a programmable controller for automatically controlling an electronic device, the types of transmission signals transmitted to and received from the electronic device and signals processed in the programmable controller (so-called control signals) are different. For this purpose, an I / O module for mutually converting signals is installed between the programmable controller and the electronic device. A plurality of I / O modules are installed, and the I / O modules are connected to each other by control signal lines. Serial transmission of control signals between communication devices is performed by serial transmission according to communication standards such as RS232C and RS485.

[0003]

In the serial transmission standard described above, hardware-related restrictions such as assignment of connector pins, transmission waveforms, voltages, and the like are specified. Therefore, signal transmission is performed using two or more types of communication standards. In such a case, a dedicated communication connector must be prepared. When a specific communication standard is used, when changing to another communication standard, all the hardware-related circuits including the connector must be replaced.

In view of the above, an object of the present invention is to provide a serial transmission method that can support a plurality of types of communication standards and minimizes hardware-related exchanges. .

[0005]

In order to achieve the above object, a first aspect of the present invention is to provide a serial communication system in which a CPU in a communication apparatus executes communication software conforming to a communication standard to perform serial transmission of signals. In the transmission method, the signal is transmitted / received, and a plurality of driver circuits having different communication standards are exchangeably detachably attachable to the communication device via a single connector to correspond to the mounted driver circuit. The serial transmission is performed by the CPU executing communication software of a communication device standard.

According to a second aspect of the present invention, in the serial transmission method according to the first aspect, a plurality of communication software for controlling the plurality of drivers are built in the communication device, and the CPU is Of the installed driver circuit, and sets communication software corresponding to the result of the identification as communication software used for communication.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a circuit configuration of an embodiment of the present invention. In FIG. 1, a communication device 1 according to the present invention is installed between a serial communication device (electronic device) 9 and an electronic device 8 such as a personal computer or a programmable controller (PLC). Note that the communication device 1 may be built in the electronic device 8 or the electronic device 9. In this system mode, signals can be transmitted between the electronic device 9 and the communication device 1 according to a plurality of communication standards.

An external interface (I / O) circuit 11 transmits a predetermined communication standard signal between the electronic device 8 and the communication device 1. The CPU 12 incorporates a plurality of communication software for serial transmission between the electronic device 8 and the electronic device 9, and automatically controls suitable communication software among the communication software to perform communication control. The memory 14 stores various control data related to the communication control and the communication data itself.

The serial communication I / F circuit 13 includes a CPU 12
The serial signal 4 is exchanged with the electronic device 9 under the above communication control. The single connector 5 has a pin configuration that can be interchangeably connected to a plurality of driver circuits described later. The driver circuits 6 and 7 generate serial signals for serial transmission,
Receive. In the present embodiment, a driver circuit for transmitting and receiving transmission signals according to RS232C and five other communication standards is prepared, and the mounted driver circuit is indicated by reference numeral 6. Note that an identification signal generating circuit 6A indicating a communication standard is built in the driver circuits 6 and 7, and the identification signal 3 is transmitted to the connector 5
Is input to the CPU 12 via the.

In such a system, when the user mounts a desired driver circuit 6 in accordance with the communication device standard of the electronic device 9, the CPU 12 automatically identifies the communication standard of the mounted driver circuit and responds to the identification result. Set up and use communication software.

FIG. 2 shows a processing procedure of the CPU 12 for this automatic identification. This processing procedure is executed when the power is turned on or in response to a reset instruction from the outside. 2, the CPU 12 reads the identification signal 3 from the driver circuit 6 (step S10) and determines the content of the identification signal 3. For example, when the identification signal is a numerical value “1”, the mounted driver circuit 6 is determined to be a driver circuit of the communication standard for RS232C (step S20 → S25), and the communication software for RS232C is set.

After the end of the processing procedure of FIG.
In order to perform communication according to the S232C standard, the same initial settings as in the related art are performed to prepare for communication.

The following embodiment can be implemented in addition to the present embodiment.

1) In the above embodiment, a plurality of communication (control) software is built in the CPU 12, but may be stored in a storage medium such as a memory.

2) The communication standard is not limited to the above-mentioned embodiment, and various communication standards can be used.

[0017]

As described above, according to the first aspect of the present invention, the driver circuit can be interchangeably connected to the connector, so that a dedicated driver circuit needs to be provided for each communication standard for the hardware configuration. Disappears.

According to the second aspect of the present invention, the type of the driver circuit to be mounted, that is, the corresponding communication standard can be automatically determined, and the communication software can be automatically set. Significantly reduced.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating a processing procedure of a CPU 12;

[Explanation of symbols]

 Reference Signs List 1 communication device 2 control circuit 3 identification signal 4 serial signal 5 connector 6, 7 driver circuit 8, 9 electronic device 11, 13 interface circuit 14 memory

Claims (2)

[Claims] 1. A serial transmission method for performing serial transmission of a signal by executing communication software conforming to a communication standard by a CPU in a communication device, comprising: transmitting and receiving the signal; The communication device is configured to be detachably removable via a single connector via a single connector, and the CPU executes communication software of a communication device standard corresponding to the installed driver circuit to perform serial transmission. Serial transmission method. 2. The serial transmission method according to claim 1, wherein the communication device includes a plurality of communication software for controlling the plurality of drivers, and the CPU includes:
A serial transmission method comprising: identifying a mounted driver circuit among the plurality of driver circuits; and setting communication software corresponding to a result of the identification as communication software used for communication.