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National Instruments Corporation
F-1
F
GPIB-VXI/C VXI Trigger Support
This appendix contains an overview of the VXI triggering capabilities of
the GPIB-VXI/C.
The GPIB-VXI/C contains a custom ASIC designed by National
Instruments called the MANTIS. The MANTIS gives direct access/control
to the VXI trigger lines as well as some unique hardware features such as a
16-bit counter/timer, a dual 5-bit tick timer, and a 10 by10 crosspoint switch
matrix. It also includes some minimal signal conditioning such as signal
inversion, variable
pulse
stretching, and
synchronization
with
a
clock
source. The MANTIS supports all VXI-defined trigger protocols on the
eight VXI TTL trigger lines and the two P2 connector ECL trigger lines.
In addition, the MANTIS has 10 external connections referred to as
General Purpose Input/Output (GPIO) connections. Figure F-1 shows the
configuration of the GPIOs on the GPIB-VXI/C. You can route a GPIO
to any or all of the VXI trigger lines or the 5-bit tick timer. By using the
built-in 10 MHz clock or GPIO 13.975 kHz, 4.9152 MHz, or TRIG IN
connections, you can generate a square wave on any or all of the backplane
trigger lines. By using the dual 5-bit tick timers, you can divide any of these
frequencies down to a lower frequency. You can also disconnect a GPIO
from its external connection and use it as a crosspoint switch location.
In this mode, you can use any single trigger line as the internal source for
the GPIO and any or all of the remaining trigger lines as the destination.
Refer to the
TTL/ECL Trigger Access Commands
section of Chapter 3,
, for information on programming the MANTIS.
