Chapter 5
Functional Overview
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National Instruments Corporation
5-7
External VXI CLK10 Synchronization
The VXIpc 870 Series computers have an SMB connector on the front
panel for an external clock. Onboard programmable logic can configure the
VXIpc 870 Series to drive its 10 MHz VXI CLK10 signal to this connector
as an output or to use this connector as an input for the 10 MHz VXI
CLK10 signal. In this fashion, you can configure multiple mainframes to
operate off a single 10 MHz system clock. All CLK10 routing features are
controllable through software.
VXI Trigger Lines
The VXIpc 870 Series gives programmers full hardware and software
control over the VXI trigger lines. The VXIpc 870 Series has two SMB
trigger I/O connectors on its front panel for routing any of the TTL trigger
lines between the backplane and external devices. The VXI trigger
interface is based on the advanced MANTIS ASIC developed by National
Instruments. The MANTIS provides the complete VXIpc 870 Series VXI
interface to the outer rows of the P2 backplane connector in a single chip.
The VXIpc 870 Series can respond to all VXI-defined protocols on all P2
TTL and ECL trigger lines at the same time. The MANTIS features an
internal cross-matrix switching system for routing between lines as well
as to and from the front panel and onboard clocks. An internal counter
gives sophisticated counting of events and interrupting on trigger edges and
pulses, as well as generating pulse trains, variable length pulses, and pulse
stretching.
VXI Interrupts
The VXIpc 870 Series can function as an interrupter and an interrupt
handler for any or all of the VXIbus interrupt lines in a VXI mainframe.
The VXIpc 870 Series works with both Release on Acknowledge (ROAK)
and Release on Register Access (RORA) devices. All interrupts are routed
to the microprocessor. The VXIpc 870 Series can also detect other VXIbus
conditions, including assertion of ACFAIL, SYSFAIL, and BERR.
