Page 1054 - The Mechatronics Handbook

37

System Interfaces

37.1 Background
Terminology and Definitions • Serial vs. Parallel
• Bit Rate vs. Baud Rate • Synchronous vs.
Asynchronous • Data Flow-Control • Handshaking
• Communication Protocol • Error Handling
• Simplex, Half-Duplex, Full-Duplex • Unbalanced
vs. Balanced Transmission • Point-to-Point
vs. Multi-Point • Serial Asynchronous Communications
• The Universal Asynchronous Receiver
Transmitter (UART)
37.2 TIA/EIA Serial Interface Standards
RS-232 Serial Interface • Functional Description
of Selected Interchange Circuits • RS-422
and RS-485 Interfaces
37.3 IEEE 488—The General Purpose Interface
M.J. Tordon Bus (GPIB)
The University of New South Wales Introduction • GPIB Hardware • Controllers,
Talkers, and Listeners • Interface Management
J. Katupitiya Lines • Handshake Lines • Data Lines DIO1-DIO8
The University of New South Wales (8 lines) • Addressing of GPIB Devices

This chapter deals with asynchronous serial interfaces described by interface standards RS-232, RS-422, and
RS-485 and with the general-purpose parallel interface bus described by IEEE-488 standard. The chapter
also provides background information, terminology and parameters, which are important in the design
of system interfaces for mechatronic systems.

37.1 Background

Modern mechatronic systems comprise a number of subsystems, which rely heavily on digital data commu-
nications. Different levels of complexity of these systems means that the requirement for data communications
range from a simple communication between two devices to systems with a large number of subsystems,
where each subsystem communicates directly or indirectly with other subsystems using a communication
network. Depending on the proximity of subsystems, different requirements are placed on data communi-
cation channels, the physical implementation of channels, and interfaces between these devices. Figure 37.1
shows a schematic diagram of a simple data communication system connecting two devices.
A data source creates the data to be transmitted to the destination system and may convert the data into
a specific form. The originating system usually does not create the data in a form suitable for transmission
over transmission lines. This is left to the transmitter, which transforms the data into a signal suitable for
transmission over a specific type of transmission line. The transmission line is generally implemented using
electrical wiring but can involve a variety of physical medium including radio frequency, infrared, and sound
signals. A transmission line provides a physical medium connecting the two systems. A receiver accepts the

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