Electrical computers and digital data processing systems: input/ – Interrupt processing
Reexamination Certificate
1999-01-06
2001-06-12
Shin, Christopher B. (Department: 2182)
Electrical computers and digital data processing systems: input/
Interrupt processing
C710S048000
Reexamination Certificate
active
06247092
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control method for command transmission and reception in a data transmission device such as a modem, and a data transmission device capable of realizing the control method. In addition, the present invention relates to a data transmission system using the data transmission device.
2. Description of the Prior Art
In a local area network, which connects a data terminal equipment to another data terminal equipment through at least two data transmission devices such as modems, various tests for checking the operation of the network, such as loop tests, are frequently executed. To execute, for example, a loop test, a data transmission device in one side sends a control command for instructing the loop test to an opposite side data transmission device.
In a conventional data transmission device such as a modem, the following methods have been used to transmit a control command to an opposite side modem.
The first method uses a so-called secondary channel. In this method, the frequency band, through which signals are transmitted, is divided into at least two bands. One of the two bands is used to transmit data and the other is used to transmit control signals such as control commands.
The second method attaches address information to command data so as to specify an opposite side device to which the control command should be transmitted. In this case, the receiving side device extracts the address information from the received signals to determine whether the command data are sent to itself.
However, the above-mentioned methods have the following problems. In fact, the first method using the secondary channel makes the bandwidth of the data transmission channel narrower since the entire frequency band must be divided into two channels. In a conventional case where a transmission speed was relatively slow, no serious problem arose due to such a narrow bandwidth. In recent years, however, a higher data transmission speed has been required. In order to increase the data transmission speed, the entire width of a transmission band of a transmission line must be used only for data transmission. It is therefore difficult to divide the transmission band into a plurality of sub-bands.
On the other hand, a strong demand exists to reduce the manufacturing cost of the devices. As a result, a trend has arisen not to provide a function to send address information to the data transmission devices from an external equipment. If the data transmission devices do not have the function to receive address information, the second method mentioned above is difficult to realize. Moreover, the possibility of setting the wrong address remains a problem in the second method.
It may be possible to provide no address information to a command. In this case, no address should be set in the data transmission devices. However, this invites a serious problem, such as dead-lock of system, when a tandem connection is adopted between two data transmission devices such as modems.
SUMMARY OF THE INVENTION
The present invention has been made to overcome the above-mentioned problems of the prior arts.
Therefore, the object of the present invention is to provide a control method of command transmission/reception in a data transmission device, the method which is capable of transmitting and receiving control commands without causing a dead-lock and without attaching any address information to the data transmission device.
Another object of the present invention is to provide a data transmission device which is capable of realizing the control method and to provide a data transmission system using the data transmission devices.
In order to accomplish the above mentioned objects, the first feature of the present invention provides a control method for command transmission in a transmission device, the transmission device being connected to an end of a transmission line and sending a signal outputted from an information processing apparatus to the transmission line, the control method comprising the steps of interrupting a path of transmission data from the information processing apparatus to the transmission line, and sending a control command to the transmission line so as to transmit the control command to an opposite side device connected to an opposite end of the transmission line.
The second feature of the present invention provides a control method of command reception in a transmission device, the transmission device being connected to an end of a transmission line and sending a signal outputted from an information processing apparatus to the transmission line, the control method comprising the steps of detecting a control command which has been sent from an opposite side device connected to an opposite end of the transmission line, responding to the detection and interrupting a path of receiving data from the transmission line to the information processing apparatus.
In the control method of command reception, when receiving the control command, the transmission device recognizes received data as command data by receiving a predetermined amount of data contained in the received data, responding to this recognition and interrupting the path of receiving data from the transmission line to the information processing apparatus.
The third feature of the present invention provides a transmission device existing between an information processing apparatus and a transmission line for sending a signal outputted by the information processing apparatus to the transmission line, the transmission device comprising, a first control unit for controlling the operation of the transmission device, a first register in which a transmission interrupt is set, according to a command sending instruction, by the first control unit, a second register in which command data are written, by the first control unit, to send a command, and a second control unit for interrupting a path of transmission data, sent from the information processing apparatus to the transmission line, when the transmission interrupt is set in the first register and sending the command data written in the second register to the transmission line.
The fourth feature of the present invention provides a transmission device between an information processing apparatus and a transmission line for sending a signal received from the transmission line to the information processing apparatus, the data transmission device comprising, a first control unit for controlling the operation of the transmission device, a first register in which a signal received from the transmission line is written, a second register in which a receiving interrupt is set by the first control unit when a command is written in the first register, a third register in which predefined data corresponding to the command are written by the first control unit when the first register receives the command, and a second control unit for interrupting a path for receiving data sent from the transmission line to the information processing apparatus when the receiving interrupt is set in the second register and sending the predefined data written in the third register to the information processing apparatus.
The fifth feature of the present invention provides a data transmission system in which a transmission device and a receiving device are oppositely arranged with each other so as to send command data from the transmission device to the receiving device, the transmission device comprising, a first control unit for controlling the operation of the transmission device, a first register in which a transmission interrupt is set according to a command sending instruction by the first control unit, a second register in which command data are written by the first control unit to send a command, and a second control unit for interrupting a path for transmission data which is inputted to the transmission device and sent to the receiving device through the transmission device when the transmission interrupt is set to the first register and sen
Sasaki Junko
Tanaka Hiroshi
Fujitsu Limited
Helfgott & Karas, PC.
Shin Christopher B.
LandOfFree
Control of command transmission and reception in a data... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control of command transmission and reception in a data..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control of command transmission and reception in a data... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2508163