System, method, and program for establishing modem communication between a master computer system and a plurality of slave computer systems through a common serial communication channel

• US 6,880,012 B1
• Filed: 08/02/2000
• Issued: 04/12/2005
• Est. Priority Date: 08/02/2000
• Status: Expired due to Fees

• Current Assignee: Lenovo International Limited (Lenovo Group Ltd.)
• Original Assignee: International Business Machines Corporation
• Inventors: Kaufman, Jillian Lynn, Suffern, Edward Stanley, Grimes, Benjamin Russell
• Primary Examiner(s): Luu, Le Hien
• Application Number:
  US09/630,912
• Time in Patent Office: 1,714 Days
• Field of Search: 709/227, 709/229, 709/209, 709/208, 709/210, 709/211, 709/228
• US Class Current: 709/227
• CPC Class Codes: H04M 11/007 with remote control systems remote control in general G08C
• CPC Class Codes: H04M 11/066 Telephone sets adapted for data transmision

Abstract

A system, method, and program for establishing modem communication between a master computer system and a plurality of slave computer systems coupled to a common serial communication channel are disclosed. An unique identification number (UIN) is assigned to each slave computer system. The slave system modems are initialized to a “receive mode.” The master computer system directs a session request to the slave computer systems through the common serial communication channel. All slave computer systems receive and respond to the session request by changing each of the modems to the “answer mode.” After all the slave computer systems respond, the master computer system requests communication with a particular slave computer system among the plurality of slave computer systems. The master computer system uses the UIN to establish communication with the particular slave computer system by sending a request from the master computer system specifying the UIN of the particular slave computer system. After the master computer system requests communication with the particular slave computer system, communication is maintained between the master computer system and only the particular slave computer system by maintaining the modem for the particular slave computer system in the “answer mode” and switching the modems for all other slave computer systems to the “receive mode.” After communication is established between the master computer system and the particular slave computer system, the master computer system controls the particular slave computer system by issuing commands.

Claims

1. A method for establishing communication between a master computer system and a particular one of a plurality of slave computer systems all coupled to a common communication channel, said method comprising:

each of the plurality of slave computer systems receiving a session request from a master computer system on the common communication channel;

in response to receipt of the session request, each of the plurality of slave computer systems changing from a receive mode to an answer mode in which all of plurality of slave computer systems are in communication with the master computer system via the common communication channel;

the plurality of stave computer systems thereafter receiving via the common communication channel a second request containing a unique identifier of a particular slave computer system among the plurality of slave computer systems;

in response to the second request, the particular slave computer system maintaining communication with the master computer system in the answer mode and each other slave computer system not identified by the unique identifier in the second request disconnecting from communication with the master computer system and returning to the receive mode.

2. The method of claim 1, wherein and further comprising:

after communication between the particular slave computer system and the master computer system is established, receiving and executing, by the particular slave computer system, commands from the master computer system.

3. A system supporting communication between a master computer system and a particular one of a plurality of slave computer systems all coupled to a common communication channel, said system comprising:

a common communication channel;

a plurality of slave communication devices all coupled to the common communication channel;

wherein, responsive to a master device transmitting a session request on the common communication channel, each of said plurality of slave communication devices responds to the session request by changing from a receive mode to an answer mode in which all of plurality of slave computer systems are in communication with the master computer system via the common communication channel; and

wherein responsive to thereafter receiving via the common communication channel a second request by the master computer system containing a unique identifier of a particular slave computer system among the plurality of slave computer systems, the particular slave computer system maintains communication with the master computer system in the answer mode and each other slave computer system not identified by the unique identifier in the second request disconnects from communication with the master computer system and returns to the receive mode.

4. The system according to claim 3, wherein:

each of the plurality of slave computer systems is assigned a respective one of a plurality of unique identifiers that can be used by the master computer system to establish communication with that slave computer system.

5. The system according to claim 4, wherein:

each of the plurality of slave computer systems has a respective non-volatile memory device that stores the respective unique identifier of that slave computer system.

6. The system according to claim 3, wherein:

after communication is established between the particular slave computer system and the master computer system, the particular slave computer system receives and executes commands from the master computer system.

7. The system according to claim 3, wherein the common communication channel is a serial communication channel.

8. The method of claim 3, wherein the common communication channel is a serial communication channel, and wherein:

receiving the session request comprises receiving the session request via the serial communication channel; and

receiving the second request comprises receiving the second request via the serial communication channel.

9. A program product for establishing communication between a master computer system aud a particular one of a plurality of slave computer systems all coupled to a common communication channel, said program product comprising:

a computer usable medium;

a control program encoded within the computer usable medium that performs the steps of;

each of the plurality of slave computer systems receiving a session request from a master computer system on the common communication channel;

in response to receipt of the session request, each of the plurality of slave computer systems changing from a receive mode to an answer mode in which all of plurality of slave computer systems are in communication with the master computer system via the common communication channel;

the plurality of slave computer systems thereafter receiving via the common communication channel a second request containing a unique identifier of a particular slave computer system among the plurality of slave computer systems; and

in response to the second, request, the particular slave computer system maintaining communication with the master computer system in the answer mode and each other slave computer system not identified by the unique identifier in the second request disconnecting from communication with the master computer system and returning to the receive mode.

10. The program product according to claim 9, wherein said control program further performs the step of:

after communication between the particular slave computer system and the master computer system is established, receiving and executing, by the particular slave computer system, commands from the master computer system.