National Instruments PXI-6683 Series User Manual

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Chapter 3 Hardware Overview
Figure 3-7. Synchronous Routing Operation
Synchronous routing can be useful for eliminating skew when sending triggers to several
destinations. For example, when sending triggers using the PXI Trigger lines, the trigger arrives
at each slot at a slightly different time. However, if the trigger is sent and received synchronously
using a low-skew synchronization clock, such as PXI_CLK10, all receiving devices can act on
the trigger at the same time, as shown in Figure 3-8.
Figure 3-8. Synchronous Routing to Multiple Destinations
Synchronous routing requires the input to be stable at a logic low or logic high state within a
window of time around the clock edge. This window of time around the clock edge is defined
by the setup time (tsetup) and hold time (thold). If the input signal changes within this window
of time, it is undetermined whether the output of the synchronous route will go to the old or new
logic state. This is important, for example, if a source is being routed synchronously to several
destinations. As shown in Figure 3-9, if the source signal changes within the setup-and-hold
Trigger Input
Synchronization
Clock
Trigger Output
Setup
Time
t
setup
Hold
Time
t
hold
Clock to Output
Time, t
CtoQ
PXI_CLK10
Trigger@Destination 2
Trigger@Destination 1
Trigger Out@Source
Trigger Synchronously Received
@Destinations 1 and 2
A
B
A: Propagation delay from source to destination 1.
B: Propagation delay from source to destination 2.

National Instruments PXI-6683 Series Specifications

General

Form Factor	PXI
Product Type	Timing and Synchronization Module
Operating Temperature Range	0 °C to 55 °C
Bus Interface	PXI
GPS Receiver	Optional
Power Requirements	+3.3 V, +5 V
Connectors	BNC, SMB
Supported Clock Sources	IRIG-B, GPS
Relative Humidity Range	10% to 90%, noncondensing
Chassis Compatibility	PXI

Summary

Legal Information

Limited Warranty

Details the warranty terms for hardware and software products.

Chapter 1 Introduction

What You Need to Get Started

Lists required items for setting up the module.

Safety Information

Crucial safety precautions for using the product.

Chapter 2 Installing and Configuring

Installing the Software

Steps for installing the NI-Sync driver software.

Installing the Hardware

General instructions for installing the module into a chassis.

Chapter 3 Hardware Overview

NI PXI-6683 Series Front Panel

Details connectors and LEDs on the module's front panel.

Hardware Features

Clock and Event Generation

Explains how the module generates clock signals and events.

Routing Signals

Chapter 4 Synchronization

GPS

Explains how GPS is used for timing and synchronization.

IRIG-B

Details the IRIG-B standard for precise timing information.

IEEE 1588

Describes synchronization over Ethernet using IEEE 1588.

PPS

How a Pulse Per Second signal is used for synchronization.

Synchronization Best Practices

Appendix A Specifications

CLKOUT Characteristics

CLKIN Characteristics (NI PXI-6683 only)

PFI<0..2>

PXI_STAR Trigger Characteristics (NI PXI-6683 only)

TCXO Characteristics

GPS Characteristics