Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1998-04-13
2002-08-20
Ngo, Ricky (Department: 2664)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S468000, C709S238000
Reexamination Certificate
active
06438146
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to asynchronous serial communication systems and methods. More particularly the present invention relates to communications between computers and serial communication devices using asynchronous serial communication
BACKGROUND OF THE INVENTION
Perhaps the most common method of communication for computers today is through serial ports. The basic communication structure for a computer having an asynchronous serial communication port for communicating with external devices through modems interfacing to remote devices such as printers or other computers is depicted in FIG.
1
. In
FIG. 1
a computer
10
communicates, through a serial port connected to modem
12
, with remote devices
20
over a communication link
14
. Remote devices
20
receive the communication via modem
16
. Communication link
14
, at the physical layer, is typically a public switched telephone network for at least some portion of the communication link. The computer
10
communicates with the remote devices
20
using one of a variety of known serial communication protocols at a selected baud rate for transmission and reception by modems
12
,
16
.
Serial communication using personal computers has changed greatly since such computers were originally introduced. In the early days of personal computing, the speeds of modems and other peripheral devices typically matched the ability of their host computer to maintain reliable and efficient connections to them. Over time, however, the processing power of personal computers has increased much more rapidly than modem communication speed capabilities. The increase in modem baud rate capability has been slowed by bandwidth limitations of the physical infrastructure (in particular of the public switched telephone network) and by signal
oise constraints. Accordingly, there has been an increase in the speed of the serial communications ports on computers that has not been matched by an equivalent increase in modem speed. Therefore, serial communication ports on personal computers are typically under-utilized as they are capable of operating faster than any one modem can operate.
OBJECTS AND SUMMARY OF THE INVENTION
In view of the above limitations it is one object of the present invention to provide systems, methods and computer program products for increasing the utilization of serial ports on computers.
It is a further object of the present invention to provide serial communications multiplexing systems, methods and computer program products which interface substantially seamlessly with applications executing on a computer.
It is an additional object of the present invention to provide serial communications multiplexing systems, methods and computer program products which require only limited hardware to upgrade existing computers and networks, while providing independent control of each channel.
In view of these and other objects, the present invention provides methods for increasing the utilization of an asynchronous serial communications port by mulitplexing a plurality of communication pipes established between the user application programs and the serial port. To the user application programs, each pipe is treated as a separate output port. A thread of code is started associated with each pipe. On receipt of data by any pipe, all of the pipes are checked to determine if a predetermined amount of data has been queued for any pipe. If so, a packet of data is created containing queued data from all pipes or null data for a pipe with no queued data. A bitmap is generated specifying which fields contain data and which contain null data. Each field is associated with a specific pipe. The packet is routed over the computer's serial port to a multiplexer which reads the bitmap, unpacks the data, and routes any contained data to the output port of the multiplexer which is associated with the respective pipe. Each output port of the multiplexer is independently configurable to operate at a baud rate (or other communication parameter such as parity) which is user selectable.
Received data at the multiplexer is similarly packeted for transmission to the computer including a field associated with each output port of the multiplexer. A bitmap is generated indicating which fields contain data and which fields contain null data. A read thread of code executing on the computer receives the packet via the serial port, reads the bitmap, reconstructs the data, and routes the data to the pipe which is associated with the output port of the multiplexer receiving the data.
A multiplexer circuit is provided which supports independent communication setting operations of the output ports as well as packetizing and reconstructing of data for multiplexing the single serial port from the computer. A clock generator provides a plurality of communication clock (baud) rates to the inputs of multiplexers with the rate applied to each asynchronous communication device in the circuit being selected by latches set by a controller which in turn selects the output of multiplexers which are coupled to the clock inputs of the asynchronous communication chips.
In one embodiment of the present invention, a method is provided for providing cooperative processing in an object oriented communication system. The object oriented communication system includes an object oriented computing environment executing on a computer which includes a multiplexer server object for connecting a plurality of applications generating data for transmission over an asynchronous serial communication port to the asynchronous serial communication port. The multiplexor server object includes a first communication pipe object for receiving data from a first one of the plurality of applications and routing data to the asynchronous serial communication port and a second communication pipe object for receiving data from a second one of the plurality of applications and routing data to the asynchronous serial communication port. The first communication pipe object executes in the object oriented computing environment to thereby perform operations including receiving data from a first one of the plurality of applications and queuing received data for routing to the asynchronous serial communication port. The first communication pipe object also determines if a selected amount of received data has been queued by one of the first or the second communication pipe objects and generates a first packet of data for routing to the asynchronous serial communication port when the selected amount of received data has been queued and routes the first packet of data to the asynchronous serial communication port. The second communication pipe object executes in the object oriented computing environment to thereby perform operations including receiving data from a second one of the plurality of applications and queuing received data for routing to the asynchronous serial communication port. The second communication pipe object also determines if the selected amount of received data has been queued by one of the first or the second communication pipe objects and generates a second packet of data for routing to the asynchronous serial communication port when the selected amount of received data has been queued and routes the second packet of data to the asynchronous serial communication port.
In a further embodiment of the present invention, the asynchronous serial communication port is coupled to a multiplexer having a plurality of output ports. The first packet of data and second packet of data are routed to the multiplexer through the asynchronous serial communication port. The first packet of data routed to the multiplexer contains a field associated with each of the plurality of applications. A bitmap field identifying associated fields of the first packet of data which contain data from an associated one of the plurality of applications and associated fields which contain null data is generated. The bitmap field is routed with the first packet of data to the multiplexer. Preferably, th
International Business Machines - Corporation
Myers Bigel & Sibley & Sajovec
Ngo Ricky
Ray-Yarletts Jeanine S.
Tran Phuc
LandOfFree
Multiplexed asynchronous serial communication systems... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multiplexed asynchronous serial communication systems..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multiplexed asynchronous serial communication systems... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2884057