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Chapter 1 Overview of NI-VXI
NI-VXI User Manual 1-2 © National Instruments Corporation
Reserved
Reserved
Reserved
Reserved
Data Low
Data High
Response/Data
Extended
Protocol/Signal
Offset
Status/Control
Device Type
ID Register
VXI Configuration
Space
Offset
3F
20
IE
1C
1A
18
0E
0C
0A
08
06
04
02
00
• Upper 16 KB of A16
space reserved for
VXI configuration space
• 64 bytes per device
• 8-bit logical
address specifies
base address for
each device
• 256 devices per
VXI system
Device
Dependent
Registers
Reserved
by VXIbus
Specification
A32 Pointer Low
A32 Pointer High
A24 Pointer Low
A32 Pointer High
16
14
12
10
Shared Memory
Protocol
Registers
Communication
Registers
Required for VXI
Message-Based
Devices
Configuration
Registers
Required for all
VXI Devices
Figure 1-1. VXI Configuration Registers
Register-Based Devices
Through the use of the VXI configuration registers, which are required
for all VXI devices, the system can identify each VXI device, its type,
model and manufacturer, address space, and memory requirements.
VXIbus devices with only this minimum level of capability are called
register-based devices. With this common set of configuration
registers, the centralized Resource Manager (RM), a software module,
can perform automatic system configuration when the system is
initialized.