Ics Electronics Corporation

Gerald K Mercola

Shih-Hsing Huang

Paul C Chu

A bus extender and data transmission method in which a continuous train of message frames of fixed size is sent along a dual serial link in both directions simultaneously. There is no handshaking between extenders unless a transmission error is detected. Message frames are constructed at a rate which is independent of serial link length and the bus data transfer rate. Each extender is divided into a bus handshake layer which sends and receives data and signals from a local bus, a management layer which continuously constructs message frames, responds to commands and receives and decodes incoming messages from a remote extender, and a transport layer. The transport layer has shift registers and encoders to receive messages from the management layer and transmit them over the serial link and has a memory to store up to 30 messages in the event of a retransmission request. The transport layer also receives messages from the serial link, checks for valid error-free messages and sends them to the management layer. It also initiates a retransmission request in the event a transmission error is detected.

Data transmission method and bus extender

A bus extender which accepts data from a parallel data bus and extends the bus by means of a serial link to another parallel bus. The bus extender comprises a local and remote station or terminal, each having a transmit and receive section. A transmit terminal receives a data frame from the parallel bus and decomposes the frame into data and management sub-frames. The local and remote terminals exchange management sub-frames, thereby starting the transmission process. A data sub-frame is then transmitted from the local to the remote station and a management sub-frame is returned from the remote station indicating receipt of the data sub-frame. Other sub-frames may be exchanged for specialized purposes, such as polling and error signalling. Specialized messages may be identified by tagging sub-frames with message codes. At the remote station, the original management and data bits are reassembled into a single data frame with placement of the bits in the same order as originally appeared at the local station. The new frame is then transferred on the data bus with all bits in parallel. The bus extender appears transparent to the two parallel bus sections.

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Pleasanton, CA, United States of America

Gerald K Mercola