National Instruments NI 6115/6120 Calibration

© National Instruments Corporation 5-1 NI 6115/6120 User Manual

5

Calibration

This chapter discusses the calibration procedures for the NI 6115/6120.

NI-DAQ includes calibration functions for performing all of the steps in the

calibration process.

Calibration refers to the process of minimizing measurement and output

voltage errors by making small circuit adjustments. On the NI 6115/6120,

these adjustments take the form of writing values to onboard calibration

DACs (CalDACs ).

Some form of device calibration is required for most applications. If you do

not calibrate the device, the signals and measurements could have very

large offset, gain, and linearity errors.

Three levels of calibration are available to you and are described in this

chapter. The first level is the fastest, easiest, and least accurate; whereas the

last level is the slowest, most difficult, and most accurate.

Loading Stored Calibration Constants

The NI61 15/6120 is factory calibrated before shipment at approximately

25 °C to the levels indicated in Appendix A, Specifications. The associated

calibration constants—the values that were written to the CalDACs to

achieve calibration in the factory—are stored in the onboard nonvolatile

memory (EEPROM). Because the CalDACs have no memory capability,

they do not retain calibration information when the device is unpowered.

Loading calibration constants refers to the process of loading the CalDACs

with the values stored in the EEPROM. NI-DAQ determines when this is

necessary and does it automatically.

In the EEPROM, there is a user-modifiable calibration area in addition to

the permanent factory calibration area. Hence, you can load the CalDACs

with values either from the original factory calibration or from a calibration

that you subsequently performed.

Contents

Main Page Important Information Warranty Copyright Trademarks Patents Compliance FCC/Canada Radio Frequency Interference Compliance Determining FCC Class FCC/DOC Warnings Class A Compliance to EU Directives Contents Chapter 4 Connecting Signals Page About This Manual Conventions National Instruments Documentation Related Documentation Introduction About the NI 6115/6120 Using PXI with CompactPCI What You Need to Get Started Software Programming Choices NI-DAQ National Instruments ADE Software Optional Equipment Custom Cabling Unpacking Safety Information Page Installing and Configuring the NI 6115/6120 Installing the Software Installing the Hardware Page Configuring the Device National Instruments Corporation 3-1 NI 6115/6120 User Manual Hardware Overview DAQ - STC RTSI Bus Figure 3-1. NI 6115 Block Diagram Analog Input The following sections describe in detail each AI category. Input Mode Note The inputs are differential only in the sense that the ground loops are broken. I/O Connector Input Polarity and Input Range Considerations for Selecting Input Ranges Input Coupling Analog Output Analog Trigger Figure 3-3. Analog Trigger Block Diagram for the NI6115/6120 Figure 3-4. Below-Low-Level Analog Triggering Mode Page Antialiasing Filters Phase-Locked Loop Circuit Correlated Digital I/O Timing Signal Routing Page Programmable Function Inputs Device and RTSI Clocks RTSI Triggers Page Figure 3-13. PXI RTSI Bus Signal Connections Connecting Signals I/O Connector Figure 4-1. I/O Connector Pin Assignment for the NI6115/6120 I/O Connector Signal Descriptions Table 4-2. Signal Descriptions for I/O Connector Pins Table 4-2. Signal Descriptions for I/O Connector Pins (Continued) Table 4-3. Analog I/O Signal Summary for the NI6115 Table 4-2. Signal Descriptions for I/O Connector Pins (Continued) Table 4-4. Analog I/O Summary for the NI 6120 Table 4-5. Digital I/O Signal Summary Types of Signal Sources Floating Signal Sources Table 4-5. Digital I/O Signal Summary (Continued) Ground-Referenced Signal Sources Connecting Analog Input Signals Connections for Ground-Referenced Signal Sources * Figure 4-2. Pseudodifferential Input Connections on the NI 6115 forGround-Referenced Signals Figure 4-3. Pseudodifferential Input Connections on the NI 6120 forGround-Referenced Signals Connections for Nonreferenced or Floating Signal Sources * Figure 4-4. Differential Input Connections on the NI6115 for Nonreferenced Signals Common-Mode Signal Rejection Considerations Working Voltage Range Connecting Analog Output Signals Connecting Digital I/O Signals Correlating DIO Signal Connections Page Power Connections Connecting Timing Signals Page Programmable Function Input Connections DAQ Timing Connections TRIG1 Signal TRIG2 Signal Page STARTSCAN Signal Page CONVERT* Signal AIGATE Signal SISOURCE Signal SCANCLK Signal EXTSTROBE* Signal Waveform Generation Timing Connections WFTRIG Signal UPDATE* Signal UISOURCE Signal General-Purpose Timing Signal Connections GPCTR0_SOURCE Signal GPCTR0_GATE Signal GPCTR0_OUT Signal GPCTR0_UP_DOWN Signal GPCTR1_SOURCE Signal GPCTR1_GATE Signal GPCTR1_OUT Signal Figure 4-35 shows the timing requirements for GPCTR1_OUT. Figure 4-35. GPCTR1_OUT Signal Timing Figure 4-36. GPCTR Timing Summary GPCTR1_UP_DOWN Signal FREQ_OUT Signal Field Wiring Considerations Calibration Loading Stored Calibration Constants Self-Calibration External Calibration Page A Specifications Analog Input Input Characteristics DC Transfer Characteristics Table A-1. NI 6115 Analog Input DC Accuracy Information Table A-2. NI 6120 Analog Input DC Accuracy Information1 Dynamic Characteristics Table A-3. NI6115 Analog Input Dynamic Characteristics Table A-4. NI6120 Analog Input Dynamic Characteristics Figure A-1. NI6115 Total Harmonic Distortion Plus Noise (THD + N) Figure A-2. NI6120 Total Harmonic Distortion Plus Noise (THD + N) Figure A-3. NI6115 High-Voltage THD + N Figure A-4. NI 6120 High-Voltage THD+ N Figure A-5. NI6115 THD + N with Filters Stability Analog Output Output Characteristics DC Transfer Characteristics Voltage Output Dynamic Characteristics Stability Digital I/O Timing I/O Trig ger s Analog Trigger Page Safety Maximum Working Voltage Electromagnetic Compatibility B Common Questions General Information Installing and Configuring the Device Analog Input and Output Page Timing and Digital I/O Page C Technical Support and Professional Services Page Glossary Numbers/Symbols A B C D E F G H I K L M N O P R S T U V W Index Numerics A B C D E F G H I K L M N O P Q R S Page T U V W