JP3148765B2 - Communication cable for matching baud rates between interfaces of different standards - 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 cable for adjusting the baud rate between interfaces of different standards, for example, RS232C and RS422.
The present invention relates to a communication cable having a built-in converter for adjusting the baud rate between interfaces of different standards.

[0002]

2. Description of the Related Art In a conventional conversion cable of RS232C and RS422, one of the connected devices is RS232C,
The communication between the other RS422 is enabled, and the signal of RS422 is transmitted to the cable.

[0003]

However, in the above-described conventional device, there is a problem that communication cannot be performed when the connected devices cannot achieve the same baud rate due to a difference in clock frequency.

Accordingly, an object of the present invention is to provide a communication cable which has solved the above problems.

[0005]

In order to achieve the above object, the present invention provides a communication cable for connecting between a first interface and a second interface of different standards, said first cable comprising: A connector between the two standards provided in a data transmission path constituting a part of the communication cable, and an external clock terminal of a device on the first interface side. An oscillator for adjusting the baud rate of the first interface to the baud rate of the second interface is attached.

[0006]

According to the present invention, for example, by supplying a clock from an oscillator provided in a cable to a device on the RS232C side, the device has the same baud rate as the device on the RS422 side.

[0007]

FIG. 1 shows a communication cable according to the present invention.
Reference numeral 2 denotes a connector on the RS232C side, reference numeral 3 denotes a connector on the RS422 side, reference numeral 1 denotes a casing attached to the connector 2, and reference numeral 4 denotes an RS422 signal cable connecting the casing 1 and the connector 3.

FIG. 2 shows the internal structure of the casing 1. The casing 1 is provided with drivers 7 and 8, which constitute a converter for RS232C and RS422, and an oscillator 9 (for example, a crystal oscillator). RS232C driver 7
The RS422 driver 8 is provided between the connector 2 and the cable 4 on the RS232C side. The oscillator 9 is connected to the connector 2 on the RS232C side.

FIG. 3 shows an internal connection state between the communication cable and the device on the RS232C side. Reference numeral 5 denotes a serial transfer circuit (IC: μPD8251) in the device on the RS232C side, which includes an address bus, a control bus, and a data bus. , The data transfer between the reception data terminal RXD, the transmission data TXD, and the external clock input terminal TXC. 6 is R
5 shows a connection part between the connector of the device on the S232C side and the connector 2, and through this terminal RX of the serial transfer circuit 5.
D, TXD and the RS232C driver 7 exchange received data and transmission data, and input a clock signal from the oscillator 9 to the terminal TXD of the serial transfer circuit 5.
Accordingly, the communication baud rate of the device on the RS232C side is determined by the frequency of the oscillator 9, and the baud rate of the device on the RS232C side is set to R by appropriately selecting this frequency.
It can be adapted to the baud rate of the device on the S422 side.

[0010]

As described above, according to the present invention, interfaces having different standards can be connected at the same baud rate.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a communication cable according to the present invention.

FIG. 2 is a diagram showing an internal structure of the cable.

FIG. 3 is a diagram showing an internal connection state between the cable and a device on the RS232C side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 RS232C connector 3 RS422 connector 4 RS422 cable

Claims (1)

(57) [Claims] 1. A communication cable for connecting a first interface and a second interface of different standards to each other, wherein a connector of the first interface forms a part of the communication cable. A converter between the two standards provided in the data transmission path, and an external clock terminal of the device on the first interface side to set the baud rate on the first interface side to the second interface. A communication cable for adjusting a baud rate between interfaces of different standards, characterized by attaching an oscillator for adjusting the baud rate.