Data transmission device, data transfer system and method

A data transfer system having a data bus and a plurality of modules for receiving and transmitting data through said data bus, wherein:

• said plurality of modules includes a first module and a second module;
• said first module having data transmitting means for outputting a data sequence having invalid data whose level is determined added at a head of the time series of the valid data onto the data bus, and
• said second module having data receiving means for removing said invalid data from said data sequence outputted by said first module onto said data bus and receiving said valid data.

A data transfer method for transferring data from a first module into a second module through a data bus, comprising the steps of:

• enabling said first module to output a data sequence having invalid data whose level is determined at a head of the time series of valid data into said data bus, after the output to said data bus is changed from a high-impedance state into a data output state whose level is set;
• and
• enabling said second module to remove said invalid data in said data sequence outputted by said first module onto said data bus and receiving said valid data.

A bus control method provided in a data transfer system having a three-state bus, comprising the steps of:

• switching said three-state bus from a high-impedance state into a level-determined state;
• and
• transmitting a data sequence composed of a plurality of data pieces onto said three-state bus a predetermined length of time later than when said three-state bus is changed into the level-determined state.

A data transfer method provided in a data transfer system having a transmitting module and a receiving module, both of which are coupled through a noncontact bus utilizing a crosstalk, comprising the steps of:

• in said transmitting module, after the state of said noncontact bus is changed into the high-impedance state, transmitting a data sequence having a level-determined valid data at the head of a plurality of data pieces onto said noncontact bus and generating a differential pulse corresponding to said data sequence on said noncontact bus;
• and
• in said receiving module, removing an influence of the differential pulse corresponding to said invalid data of said data sequence from the differential pulses on said noncontact bus and reproducing said plurality of data pieces from the corresponding differential pulses to said plurality of data pieces.