Patent ID: 6442196
Filing Date: 2002-08-27
Classification: H04L

Abstract:
A method for asynchronously transferring user data between a first data communications device and a second data communications device over a data link, the method comprising:transmitting a first control code from the first data communications device to the second data communications device wherein the first control code requests initialization of the second data communications device to receive the user data; transmitting a second control code from the second data communications device to the first data communications device in response to the first control code, wherein the second control code indicates that the second data communications device is initialized to receive the user data and wherein the second control code is different from other ones of the control codes that acknowledge receipt of the user data; transmitting a third control code from the first data communications device to the second data communications device in response to the second control code, wherein the third control code identifies a start of a frame of the user data; transmitting at least a portion of the user data from the first data communications device to the second data communications device after transmitting the third control code; transmitting a fourth control code from the first data communications device to the second data communications device after transmitting the user data, wherein the fourth control code identifies an end of the frame of the user data; transmitting a check value from the first data communications device to the second data communications device; and transmitting a fifth control code from the second data communications device to the first data communications device in response to processing the check value, wherein the fifth control code acknowledges that the frame of the user data is error-free, and wherein the fifth control code is different from the second control code; wherein said user data includes a bit string that happens to match the character bit sequence of one of said control codes; and said method further including the steps of: at said first data communications device, encoding said bit string that matches said control code as a predetermined control code that does not match said control code; transmitting said predetermined control code to said second data communications device: and upon receipt of said predetermined control code at said second data communications device, replacing said predetermined code with said bit string of user data that matches said control code.