National Instruments PCI-6251 User Manual page 7

Contents
37-Pin M Series Cables and Accessories.................................................................. 2-8
37-Pin Cables.................................................................................................... 2-9
37-Pin Screw Terminal Accessories ................................................................. 2-9
RTSI Cables ...................................................................................................... 2-9
37-Pin Custom Cabling..................................................................................... 2-9
Signal Conditioning .......................................................................................................... 2-10
Sensors and Transducers...........................................................................................2-10
Signal Conditioning Options .................................................................................... 2-10
SCXI ................................................................................................................. 2-10
SCC................................................................................................................... 2-11
Programming Devices in Software ................................................................................... 2-11
Chapter 3
Connector and LED Information
I/O Connector Signal Descriptions ................................................................................... 3-1
+5 V Power Source ........................................................................................................... 3-5
USER 1 and USER 2 ........................................................................................................ 3-5
RTSI Connector Pinout..................................................................................................... 3-7
LED Patterns..................................................................................................................... 3-7
Chapter 4
Analog Input
Analog Input Range .......................................................................................................... 4-2
Analog Input Lowpass Filter ............................................................................................ 4-3
Analog Input Ground-Reference Settings......................................................................... 4-4
Configuring AI Ground-Reference Settings in Software ......................................... 4-6
Multichannel Scanning Considerations ............................................................................ 4-6
Analog Input Data Acquisition Methods .......................................................................... 4-9
Software-Timed Acquisitions ................................................................................... 4-9
Hardware-Timed Acquisitions.................................................................................. 4-9
Analog Input Triggering ................................................................................................... 4-10
Connecting Analog Input Signals ..................................................................................... 4-11
Connecting Floating Signal Sources................................................................................. 4-12
What Are Floating Signal Sources?.......................................................................... 4-12
When to Use Differential Connections with Floating Signal Sources......................4-12
When to Use Non-Referenced Single-Ended (NRSE) Connections with
Floating Signal Sources ......................................................................................... 4-12
When to Use Referenced Single-Ended (RSE) Connections with Floating
Signal Sources ....................................................................................................... 4-13
Using Differential Connections for Floating Signal Sources ................................... 4-13
Using Non-Referenced Single-Ended (NRSE) Connections for
Floating Signal Sources ......................................................................................... 4-16
Using Referenced Single-Ended (RSE) Connections for Floating
Signal Sources ....................................................................................................... 4-17
vi | ni.com