National Instruments NI-VXI - Manual (Page 127)

Glossary
NI-VXI User Manual G-4 © National Instruments Corporation
C
clearing Replacing the information in a register, storage location, or storage unit
with zeros or blanks.
CLK10 A 10 MHz, ± 100 ppm, individually buffered (to each module slot),
differential ECL system clock that is sourced from Slot 0 and
distributed to Slots 1 through 12 on P2. It is distributed to each slot
as a single-source, single-destination signal with a matched delay of
under 8 ns.
command A directive to a device. In VXI, three types of commands are as
follows:
• In Word Serial Protocol, a 16-bit imperative to a servant from its
Commander (written to the Data Low register);
• In Shared Memory Protocol, a 16-bit imperative from a client to a
server, or vice versa (written to the Signal register);
• In Instrument devices, an ASCII-coded, multi-byte directive.
Commander A message-based device which is also a bus master and can control one
or more Servants.
communications In message-based devices, a set of registers that are accessible to the
registers device’s Commander and are used for performing Word Serial Protocol
communications.
configuration registers A set of registers through which the system can identify a module
device type, model, manufacturer, address space, and memory
requirements. In order to support automatic system and memory
configuration, the VXIbus specification requires that all VXIbus
devices have a set of such registers.
controller A device that is capable of controlling other devices. A desktop
computer with a MXI interface board, an embedded computer in a
VXI chassis, a VXI-MXI, and a VME-MXI may all be controllers
depending on the configuration of the VXI system.
CR Carriage Return; the ASCII character 0Dh.