National Instruments DAQCard-1200 - page 45

Chapter 3 Signal Connections

© National Instruments Corporation 3-23 DAQCard-1200 User Manual

In the posttrigger mode, EXTTRIG serves as an external trigger that

initiates a data acquisition sequence. When you use counter A0 to time

sample intervals, a rising edge on EXTTRIG starts counter A0 and the data

acquisition sequence. When you use EXTCONV* to time sample intervals,

data acquisition is enabled on a rising edge of EXTTRIG followed by a

rising edge on EXTCONV*. The first conversion occurs on the next falling

edge of EXTCONV*. Further transitions on the EXTTRIG line have no

effect until a new data acquisition sequence is established.

Figure3 -1 3 shows a possible controlled data acquisition sequence using

EXTCONV* and EXTTRIG. The rising edge of EXTCONV* that enables

external conversions must occur a minimum of 50 ns after the rising edge

of EXTTRIG. The first conversion occurs on the next falling edge of

EXTCONV*.

Figure 3-13. Posttrigger DAQ Timing

In the pretrigger mode, EXTTRIG serves as a stop-trigger signal. Data is

acquired both before and after the stop trigger occurs. A/D conversions are

software enabled, which initiates the data acquisition operation. However,

the sample counter is not started until a rising edge is sensed on the

EXTTRIG input. Conversions remain enabled until the sample counter

counts to zero. The maximum number of samples acquired after the stop

trigger is limited to 65,535. The number of samples acquired before the

trigger is limited only by the size of the memory buffer available for data

acquisition.

tw 50 ns minimum

EXTTRIG

VIH

VIL

tw

EXTCONV*

CONVERT

td 50 ns minimum

tw

td

Contents

Main Page Important Information Warranty Copyright Trademarks WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS Contents Chapter 4 Theory of Operation Page Tables About This Manual Organization of This Manual Conventions Used in This Manual National Instruments Documentation Related Documentation Introduction About the DAQCard-1200 What You Need to Get Started Software Programming Choices LabVIEW and LabWindows/CVI Application Software NI-DAQ Driver Software Register-Level Programming Optional Equipment Unpacking Installation and Configuration Installation Configuration Analog Input Configuration Analog Input Polarity Analog Input Mode RSE Input (Eight Channels, Default Setting) NRSE Input (Eight Channels) DIFF Input (Four Channels) Analog Output Configuration Analog Output Polarity Digital I/O Configuration Counter Configuration Signal Connections I/O Connector Figure 3-1. DAQCard-1200 I/O Connector Pin Assignments Signal Connection Descriptions Analog Input Signal Connections + Types of Signal Sources Floating Signal Sources Ground-Referenced Signal Sources Input Configurations Differential Connection Considerations (DIFF Configuration) Differential Connections for Grounded Signal Sources Figure 3-3. Differential Input Connections for Grounded Signal Sources Differential Connections for Floating Signal Sources Figure 3-4. Differential Input Connections for Floating Sources Single-Ended Connection Considerations Single-Ended Connections for Floating Signal Sources (RSE Configuration) Single-Ended Connections for Grounded Signal Sources (NRSE Configuration) Common-Mode Signal Rejection Considerations Analog Output Signal Connections Digital I/O Signal Connections Page Port C Pin Connections Timing Specifications Mode 1 Input Timing Mode 1 Output Timing Mode 2 Bidirectional Timing Page DAQ and General-Purpose Timing Signal Connections DAQ Timing Connections Page Page Page General-Purpose Timing Signal Connections Page Page Figure 3-18. Frequency Measurement Application Chapter 3 Signal Connections DAQCard-1200 User Manual 3-30 National Instruments Corporation Figure 3-19. General-Purpose Timing Signals The GATE and OUT signals in Figure3-19 are referenced to the rising edge of the CLK signal. Power Connections National Instruments Corporation 4-1 DAQCard-1200 User Manual Theory of Operation This chapter explains the operation of each functional unit of the DAQCard-1200. Figure 4-1. DAQCard-1200 Block Diagram Functional Overview The block diagram in Figure 4-1 shows a functional overview of the DAQCard-1200. PC Card I/O Channel Interface Circuitry Timing Chapter 4 Theory of Operation Figure 4-3. Timing Circuitry DAQCard-1200 User Manual 4-4 National Instruments Corporation Analog Input Analog Input Circuitry Page Data Acquisition Timing Data Acquisition Operation Continuous Data Acquisition Interval Data Acquisition Data Acquisition Rates Page Analog Output Analog Output Circuitry Power-On State DAC Timing Digital I/O Calibration Calibration at Higher Gains Calibration Equipment Requirements Using the Calibration Function Page A Specifications Analog Input Input Characteristics Transfer Characteristics Amplifier Characteristics Dynamic Characteristics Stability Analog Output Output Characteristics Transfer Characteristics Page Timing I/O Digital Trigger Bus Interface Power Requirement Physical Page B Differences among the Lab-PC+, the DAQPad-1200, and the DAQCard-1200 Page C Power-Management Modes Page D PC Card Questions and Answers Configuration Operation Resources Page Page E Technical Support Resources NI Web Support Online Problem-Solving and Diagnostic Resources Software-Related Resources Worldwide Support Glossary Numbers/Symbols A B C D E F G Page Page V Index Numbers A B C D E F G I L M N O R S T U V W