Technical Concepts for Technical Writers

address bus - see bus

bus

clock bus speed - see bus

Controller card - see VME bus

data bus - see bus

interrupt, Interrupt Request (IR or IRQ)

Interrupt Service Routine (ISR)

Master card - see VME bus

motion control systems

motors

servo

Slave card - see VME bus

VME bus - see also bus

bus

A bus is a transmission line with devices attached directly to it. The devices send and receive data signals via the bus transmission line.

Note that the transmitted signals pass to all of the attached devices, but each device only pays attention to the signals intended for it.

There are two basic parts to a bus system:

• The data bus: Transmits the actual data.
• The address bus: Transmits the intended destination for the data.

A bus is set to run at a specified speed; this is the clock bus speed. 

• The clock bus speed allows all the devices on the line to transfer data at the same speed; this allows slower devices to "keep up." Clock bus speed is measured in MHz.

interrupt, Interrupt Request (IR or IRQ)

When a device has data to transmit (i.e., has changed status), it interrupts the controlling processor. That is, the device sends an Interrupt Request (IR or IRQ) to the processor to request attention.

See also Interrupt Service Routine (ISR).

Interrupt Service Routine (ISR)

When a processor receives an Interrupt Request (IR) from a device, it initiates an Interrupt Service Routine (ISR) to process the device's data.

In general, the processor will actually complete its current activity and postpone its next instruction to perform the ISR.

motion control systems

Motion control systems control the position, velocity, and torque (the amount of force that can be exerted) of a mechanical system. They consist of:

• A controller
• An amplifier
• A motor

Note that controllers often utilize a Digital Signal Processor (DSP) board.

motors

Motors can be either linear or rotary motors. That is, they can produce either linear or rotational motion. They generate movement (torque) using electromagnetic fields. 

servo

A servo is a motor attached to a position feedback device. It provides precision motion control.

See also motion control systems.

VME bus

The VME bus system was first designed and introduced by Motorola, Signetics, Mostek, and Thompson CSF.

The VME bus is a modular bus system. This modularity allows the system to be:

• Configured for a wide variety of applications, from the most simple to the highly complex
• Upgraded with greater ease
• Serviced with greater ease

In general, the VME has three main components:

• The Controller card: The Controller controls access to the bus by the Master card. It handles interrupts.
• The Master card(s): The Master controls the data and address aspects of the bus system. That is, it controls data transmission to and from the Slave cards. Note that a VME bus can have more than one Master card.
• The Slave cards: The Slave cards monitor the data and address aspects of the bus system. When it recognizes a signal intended for it, it transmits or receives data as directed by the Master.

VME stands for VersaModular Eurocard. 

Copyright © 2001 by Honey Treetot's Tree House Club.