Multiplex communications – Channel assignment techniques – Polling
Reexamination Certificate
1999-01-05
2004-08-03
Nguyen, Chau (Department: 2663)
Multiplex communications
Channel assignment techniques
Polling
C370S461000, C370S462000
Reexamination Certificate
active
06771656
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to communication right determination methods, information processing apparatuses and computer-readable recording mediums, and more particularly to a communication right determination method for determining a right to make a communication among a host computer and a plurality of terminal equipments, an information processing apparatus which uses the communication right determination method, and a computer-readable recording medium which is recorded with a program for carrying out the communication right determination method.
When making a data communication among a host computer and a plurality of terminal equipments, a communication adapter (hereinafter simply referred to as an adapter) is coupled to each terminal equipment, and the adapters are coupled by a cable while one adapter is selectively coupled to the host computer. The terminal equipment confirms from a signal line a connection state of the host computer and the other terminal equipments, and makes a communication in a state where the other terminal equipments are not making a communication.
According to the above described method, the adapter must be provided with a means for confirming and judging a state of the signal line. As a result, the cost of the adapter becomes high.
As another method of determining the right to make a communication, there is a method which adds identification (ID) numbers to the plurality of terminal equipments. The ID numbers are managed by the host computer, and a polling is successively made to the plurality of terminal equipments using the ID numbers, so as to determine the right to make a communication. However, according to this method, it takes time to make the communication because the polling must successively be made to the plurality of terminal equipments.
Therefore, there are demands to realize a communication right determination method which can be realized with ease at a low cost.
FIG. 1
is a diagram showing a first example of a conventional system. In this conventional system, a host computer
93
makers a data communication with a plurality of terminal equipments
91
-
1
through
91
-N. A communication adapter
92
is provided with respect to each of the terminal equipments
91
-
1
through
91
-N, and the host computer
93
and the terminal equipments
91
-
1
through
91
-N are coupled by cables
94
in a daisy-chain.
When the terminal equipments
91
-
1
through
91
-N communicate with the host computer
93
, the adapter
92
detects the state of the signal on the cable
94
, and makes a connection to the host computer
93
if there is no other terminal equipment in use.
On the other hand, the plurality of terminal equipments and the host computer can be coupled by assigning arbitrary ID numbers to each of the terminal equipments. In this case, the host computer can successively carry out a polling with respect to the terminal equipments using the ID numbers.
FIG. 2
is a diagram for explaining the operation of a second example of the conventional system which uses such ID numbers.
In a communication system shown in
FIG. 2
, a host computer
101
supplies a polling data to a terminal equipment
102
-
1
having an ID number “001”. If no request is generated in the terminal equipment
102
-
1
to make a communication with the host computer
101
when the polling data is supplied from the host computer
101
, the terminal equipment
102
-
1
responds to the host computer
101
by returning a communication denial data as a response data.
The host computer
101
receives and analyzes the response data from the terminal equipment
102
-
1
. If the analyzed response data is the communication denial data, the host computer
101
supplies the polling data to the terminal equipment having the next ID number, and the above described operation is repeated in a similar manner.
For example, if the response data from the terminal equipment
102
-N is a communication acknowledge data, the host computer
101
communicates with the terminal equipment
102
-N by carrying out a data communication process. During this time when the host computer
101
communicates with the terminal equipment
102
-N, the polling data is not supplies to any of the terminals
102
-
1
through
102
-N.
When the communication between the host computer
101
and the terminal
102
-N ends, the host computer
101
again successively supplies the polling data to the terminal equipments
102
-
1
through
102
-N starting from the terminal equipment
102
-
1
having the first ID number “001”, and operations similar to that described above are repeated.
However, according to the first example which detects the state of the signal line at the communication adapters coupled in the daisy-chain as shown in
FIG. 1
, confirms the communication state, and makes the communication only when no communication is made, it is necessary to provide in the communication adapters a hardware for detecting the state of the signal line. As a result, there is a problem in that the cost of the communication adapter, and thus, the communication system, increases.
On the other hand, according to the second example which assigns the arbitrary ID numbers to the terminal equipments and successively makes the polling with respect to the terminal equipments using the ID numbers as shown in
FIG. 2
, the ID number must be assigned to each of the terminal equipments, and the host computer must manage the ID numbers. Hence, there were problems in that the process becomes complex at both the terminal equipments and the host computer.
In addition, since the second example makes the polling from the host computer using the ID number with respect to each terminal equipment which is coupled to the host computer, there is another problem in that it takes time for the communications of all of the terminal equipments to end when a relatively large number of terminal equipments are coupled to the host computer.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention is to provide a novel and useful communication right determination method, information processing apparatus and computer-readable recording medium, in which the problems described above are eliminated.
Another and more specific object of the present invention is to provide a communication right determination method, information processing apparatus and computer-readable recording medium which enable communications to be made at a low cost and within a relatively short communication time under an environment in which a plurality of terminal equipments are coupled to a host computer.
Still another object of the present invention is to provide a communication right determination method for determining a right to communicate between a host unit and a plurality of terminal equipments coupled to the host unit, comprising the steps of (a) transmitting polling information from the host unit simultaneously to the terminal equipments, (b) transmitting connection response information from the terminal equipments to the host unit at times which are different for each of the terminal equipments depending on the polling data received from the host unit, and (c) establishing a communication between the host unit and a predetermined terminal equipment from among the terminal equipments depending on the connection response information which is received from each of the terminal equipments. According to the communication right determination method of the present invention, it is possible to simultaneously transmit the polling information from the host unit to the terminal equipments using the same line, and the responses can be recognized independently at the host unit even when the responses are transmitted from the terminal equipments on the same line. As a result, the line can be simplified in that there is no need to couple the host unit and the terminal equipments using independent lines.
A further object of the present invention is to provide an information processing apparatus which communicates with a plu
Fujitsu Limited
Hyun Soon-Dong
Katten Muchin Zavis & Rosenman
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