Samsung SMO-150QP Spezifikationen PDF herunterladen (Seite 12)

1 - 3

1.1.2.3 VXIbus System Configurations

VXIbus systems utilize a chassis with a backplane and a common power supply. Modules plug into

the chassis from the front and communicate to each other over the backplane. The left most slot in

each chassis is labeled slot 0 and it is reserved for the system or chassis controller. Modules in the

other slots are servants to the system controller but can also be controllers and have their own

servants. The Slot 0 controller must be capable of performing the resource manager function which

initializes the other modules and assigns logical addresses for dynamically addressed devices,

interrupt lines, and trigger lines. The Slot 0 controller may be an embedded computer or it may

simply be a translator module driven by an external computer.

Each VXI device is addressed by its logical address. The address may be static and preset by the user

or dynamic and set by the resource manager function during system initialization. The VXIbus

specification allows for 256 logical addresses. Address 0 is reserved for the Slot 0 controller and

address 255 is reserved for dynamic addressable devices that will have their address defined by the

resource manager. A VXI system can contain a maximum of 254 logical devices.

A module may be a single logical device or contain multiple logical devices. Physically the module

can also be one slot wide or occupy multiple slots. Full rack wide VXI chassis have 13 slots on a

1.2 inch centers and can hold up to 13 one slot wide modules. Chassis extenders allow multiple

chassis to be interconnected together producing systems of up to 254 logical devices.

VXI based systems can also incorporate non-VXIbus devices. The most common variations are the

inclusion of GPIB instruments in the system or the use of VME cards in the VXI chassis. Slot 0

controllers commonly have a GPIB interface for controlling the GPIB instruments so that their

operation can be controlled from the same program as are the VXI modules. VME cards can function

in a VXI chassis because the VXIbus Specification maintained compatibility with the VME bus by

retaining the VME signals definitions for P1 and the center row of P2. Provisions were also made

to address the registers in the VME modules just as they are currently addressed in a VME bus system.

1.1.2.4 Data Transfer Methods

VXI modules can be register or message based . Register based modules are typically controlled by

direct reads or writes to registers in the module. Message based modules communicate with word

serial messages that are strings of ASCII or binary bytes. Word transfer uses the VXI word serial

protocol that examines bits in the modules's protocol register to maintain an orderly data transfer.

Because of the word serial protocol, register based modules are typically faster than message based

modules but they lack the intelligence of message based modules. A new Fast Data Channel

specification provides for direct transfer of data from a module's memory to the Slot 0 Controllers

at rates up to 32 Mbytes per second.

1.1.2.5 Additional information about the VXIbus

For additional information, contact the VXI Consortium for a copy of the VXI specification, the

VXIplug&play Alliance for a copy of the VISA specification or ICS Electronics for Application

Bulletins that describe VXI applications.

Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 66 67

Keine Kommentare

Samsung SMO-150QP Spezifikationen Seite 12