rs 449 serial interfaces

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By: pp12479 (41 month(s) ago)

very good

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Presentation Transcript

RS 449 Serial Interface Standards : 

RS 449 Serial Interface Standards

Snapshot : 

Serial Interfaces Need for a standard, its requirements RS 449 Serial Interfacing Pin designations Primary goals Category 1 and Category 2 circuits Comparison with RS 232 Snapshot

Serial Interfaces : 

To ensure an orderly flow of data between a DTE and a DCE, a standard serial interface is used to connect them. Serial Interfaces

Requirements of a standard : 

A serial interface standard should provide the following: A specific range of voltages to transmit and receive signals Limitations for electrical parameters of the transmission line to be taken into account Standard cable and connectors Functional description of each signal on the interface Requirements of a standard

RS 449 Serial Interface Standards : 

The data rates had exceeded the capabilities of RS 232 interfaces Consequently, in 1977 EIA introduced RS 449 with the intention of replacement of RS 232 However, it is a generic connector specification. It is not an actual interface When combined with RS-422A or RS-432A,these cables could replace RS 232 cables RS 449 Serial Interface Standards

Primary Cable : 

Primary Cable

Secondary Cable : 

Secondary Cable

Primary goals of new specifications : 

Compatibility with the RS-232 interface standard Replace the set of mnemonics used with RS 232 interface with more meaningful names Provide separate cables and connectors for the primary and secondary data channels Provide single ended or balanced transmission Reduce crosstalk Primary goals of new specifications

Slide 9: 

Offer higher data transmission rates Provide loopback capabilities Improve performance and reliability Specify a Standard connector With RS 422A,acts a balanced interface cable. Operating speed:10Mbps and Span distances:1200 metres With RS 423A,acts as an unbalanced interface cable. Operating speed:100kbps and Span distances: upto 90 metres

Category 1 and Category 2 circuits : 

Category 1 and Category 2 circuits

Functional Description : 

Functional Description