Pseudo-full duplex communication using a half duplex communication protocol

Abstract

In a communication system having a master-slave arrangement communicating with each other using the RS485 protocol, an FPGA with a buffer memory is provided in the master and slave, respectively, to handle the actual communication. The CPUs of the master and slave transfer data to and from the respective buffer memory. The master's FPGA initiates and maintains communication with the slave's FPGA. The masters FPGA and the slave's FPGA communicate with each other using the RS485 protocol by transmitting requests, acknowledgements and data. From the standpoint of the CPUs of the master and slave, the communication appears to be full duplex, although the actual communication between the FPGAs is half duplex. One particular application of the communication method is a KVM switch system where the KVM switch acts as the master and the computers connected to the KVM switch act as slaves.

Description

technical field [0001] The invention relates to a communication method, in particular to a method for achieving virtual full-duplex communication in a half-duplex communication method. Background technique [0002] The traditional RS485 (also known as EIA-485) communication method uses a master-slave arrangement (master-slave arrangement), which is that the master sends a request first, and then the slave responds. Such a system is a half-duplex system because each device (master or slave) in the system cannot transmit and receive signals at the same time. If the slave has a piece of data to send to the master, the slave must wait until it receives a request from the master. If the time interval between several requests sent by the master end is very long, the data from the slave end will not be transmitted to the master end in time, thus causing a delay in data transfer. On the other hand, if the time interval for sending requests from the master end is shortened, the bur...

AI Technical Summary

Problems solved by technology

If the time interval between several requests sent by the master end is very long, the data from the slave end will not be transmitted to the master end in time, thus causing a delay in data transfer

On the other hand, if the time interval for sending requests from the master is shortened, the burden on the master CPU and the slave CPU will be increased.

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