Code Instrument Overview
Appendix C
GPIB-VXI User Manual
C-6
© National Instruments Corporation
• VME cards (CPU, Register-Based, memory, and so on)
• CDS 73A-852 adapter module
Downloaded CIs and EPROMed CIs
You can download CIs in the form of binary code into the GPIB-VXI's RAM. The downloaded
modules are called
Downloaded CIs
, or
DCIs
. The CI Configuration local commands download
and initialize CIs. You can use the DCI form to develop CIs without programming EPROMs, or
to create disk-loadable CI applications.
The GPIB-VXI also has an interface for installing CIs in onboard EPROMs, including a
mechanism for automatically initializing them at system startup. CIs stored in the EPROMs are
called
EPROMed CIs
, or
ECIs
. You can use the ECI form to create stand-alone CI applications.
Resident CIs
A Resident CI (RCI) that communicates with a CDS 73A-852 adapter is supplied by National
Instruments as part of the GPIB-VXI firmware. The 852 adapter is a non-VXI device that
requires a special code module somewhere in the system with a Message-Based interface.
Appendix C,
Using the CDS-852 Adapter Code Instrument
, contains information about installing
and using the 852 adapter CI.
Summary
With these capabilities, a CI can emulate or replace any existing VXI or VME device, or extend
a device's native capabilities to new levels of functionality, as a disk-loadable or stand-alone
solution. To summarize, CIs improve the system structure for the following reasons:
• GPIB traffic is greatly reduced.
• Register-Based and non-VXI devices can be treated as if they were Message-Based.
– The GPIB Controller sees one type of instrument (an IEEE-488 instrument).
– Standard IEEE-488 communication is possible with all types of VXI/non-VXI
instruments.
• GPIB control of a VXIbus system can be implemented uniformly at a high level.
• Application software is simplified due to uniformity of control.
• System performance is greatly increased.
– Direct access results in a tight coupling with its servants.
– Distributed processing removes burden from outside controller.
– Access to VXIbus bandwidth is accomplished without GPIB overhead.
