National Instruments DAQ M Series - Manual (Page 5)

Contents
NI 6236 User Manual vi ni.com
Chapter 4
Analog Input
Analog Input Circuitry .................................................................................................. 4-1
Analog Input Range....................................................................................................... 4-2
Connecting Analog Current Input Signals .................................................................... 4-3
Method 1 ......................................................................................................... 4-3
Method 2 ......................................................................................................... 4-4
Analog Input Ground-Reference Settings ..................................................................... 4-5
Configuring AI Ground-Reference Settings in Software................................ 4-7
Multichannel Scanning Considerations ......................................................................... 4-8
Use Short High-Quality Cabling..................................................................... 4-8
Minimize Current Step between Adjacent Channels ...................................... 4-8
Avoid Scanning Faster Than Necessary ......................................................... 4-9
Example 1 ......................................................................................... 4-9
Example 2 ......................................................................................... 4-9
Analog Input Data Acquisition Methods....................................................................... 4-10
Software-Timed Acquisitions ......................................................................... 4-10
Hardware-Timed Acquisitions ........................................................................ 4-10
Buffered ............................................................................................ 4-10
Non-Buffered.................................................................................... 4-11
Analog Input Triggering................................................................................................ 4-11
Field Wiring Considerations.......................................................................................... 4-11
Analog Input Timing Signals ........................................................................................ 4-12
AI Sample Clock Signal.................................................................................. 4-15
Using an Internal Source .................................................................. 4-15
Using an External Source ................................................................. 4-15
Routing AI Sample Clock Signal to an Output Terminal................. 4-16
Other Timing Requirements ............................................................. 4-16
AI Sample Clock Timebase Signal ................................................................. 4-17
AI Convert Clock Signal................................................................................. 4-17
Using an Internal Source .................................................................. 4-18
Using an External Source ................................................................. 4-18
Routing AI Convert Clock Signal to an Output Terminal................ 4-18
Using a Delay from Sample Clock to Convert Clock ...................... 4-19
Other Timing Requirements ............................................................. 4-19
AI Convert Clock Timebase Signal ................................................................ 4-20
AI Hold Complete Event Signal ..................................................................... 4-20
AI Start Trigger Signal.................................................................................... 4-21
Using a Digital Source...................................................................... 4-21
Routing AI Start Trigger to an Output Terminal .............................. 4-21
AI Reference Trigger Signal ........................................................................... 4-22
Using a Digital Source...................................................................... 4-23
Routing AI Reference Trigger Signal to an Output Terminal .......... 4-23