Glossary
© National Instruments Corporation
Glossary-13
VME-MXI-2 User Manual
synchronous communications
A communications system that follows the command/response
cycle model. In this model, a device issues a command to
another device; the second device executes the command and
then returns a response. Synchronous commands are executed in
the order they are received.
Synchronous MXI Block Protocol A block data transfer protocol defined by the MXI-2
specification for high-performance data transfers.
Synchronous Protocol
The most basic trigger protocol, simply a pulse of a minimum
duration on any one of the trigger lines.
SYSFAIL
A VMEbus signal that is used by a device to indicate an internal
failure. A failed device asserts this line. In VXI, a device that
fails also clears its PASSed bit in its Status register.
SYSRESET
A VMEbus signal that is used by a device to indicate a system
reset or power-up condition.
System Controller
See MXIbus System Controller, VMEbus System Controller.
system hierarchy
The tree structure of the Commander/Servant relationships of all
devices in the system at a given time. In the VXIbus structure,
each Servant has a Commander. A Commander can in turn be a
Servant to another Commander.
system RAM
RAM installed on your personal computer and used by the
operating system, as contrasted with onboard RAM, which is
installed on the VME-MXI-2.
T
terminators
Also called terminating networks; devices located at the ends of
a MXIbus daisy-chain that are used to minimize reflections and
bias signals to their unasserted states.
TERMPWR
Termination Power; 3.4 VDC for the MXIbus.
trigger
Either TTL or ECL lines used for intermodule timing.
TTL
Transistor-Transistor Logic
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