National Instruments 9205, 9206 Calibration Procedure
NI 9205/9206 Calibration
Procedure
This document contains information about calibrating National
Instruments 9205/9206 modules using NI-DAQmx. This calibration
procedure is intended for metrology labs.
This document does not discuss programming techniques or compiler
configuration. The NI-DAQmx driver contains online help files that have
compiler-specific instructions and detailed function explanations. You can
install these help files when you install NI-DAQmx on the calibration
computer.
The NI 9205 and NI 9206 should be calibrated at a regular interval as
defined by the measurement accuracy requirements of your application.
National Instruments recommends that you routinely perform a complete
calibration at least once every two years. You can shorten this interval based
on the accuracy demands of your application or requirements of your
processes. Self-calibration can be performed as needed or when the
temperature varies by 5 °C or more from the last external calibration.
Contents
Conventions ............................................................................................ 2
Calibration Options ................................................................................. 3
Self-Calibration................................................................................ 3
External Calibration......................................................................... 3
Software and Documentation Requirements........................................... 3
Software ........................................................................................... 3
Documentation................................................................................. 4
Calibration Requirements .......................................................................5
Password .......................................................................................... 5
Test Equipment ................................................................................ 5
Test Conditions ................................................................................ 5
Calibration Process ................................................................................. 5
Calibration Process Overview ......................................................... 5
Initial Setup...................................................................................... 6
Self-Calibration................................................................................ 6
Verification Procedure......................................................................7
Adjustment Procedure ......................................................................10
AI Absolute Accuracy Tables and Formulas...........................................12
Device Test Limits...................................................................................13
Using the Table.................................................................................13
Range.........................................................................................13
Test Point...................................................................................14
2-Year Limits ............................................................................14
Where to Go for Support .........................................................................15
Conventions
The following conventions appear in this manual:
» The » symbol leads you through nested menu items and dialog box options
to a final action. The sequence File»Page Setup»Options directs you to
pull down the File menu, select the Page Setup item, and select Options
from the last dialog box.
This icon denotes a note, which alerts you to important information.
bold Bold text denotes items that you must select or click in the software, such
as menu items and dialog box options. Bold text also denotes parameter
names and hardware labels.
italic Italic text denotes variables, emphasis, a cross-reference, or an introduction
to a key concept. Italic text also denotes text that is a placeholder for a word
or value that you must supply.
monospace Monospace text denotes text or characters that you should enter from the
keyboard, sections of code, programming examples, and syntax examples.
This font is also used for the proper names of disk drives, paths, directories,
programs, subprograms, subroutines, device names, functions, operations,
variables, filenames, and extensions.
NI 9205/9206 NI 9205/9206 refers to the NI 9205 and NI 9206.
NI 9205/9206 Calibration Procedure 2 ni.com
Calibration Options
The NI 9205/9206 support two types of calibration: self-calibration and
external calibration.
Self-Calibration
Self-calibration, also known as internal calibration, uses a software
command and requires no external connections. Self-calibration improves
measurement accuracy by compensating for variables such as temperature
that might have changed since the last external calibration. Self-calibration
retains the traceability of the external calibration and can be performed as
necessary to compensate for environmental changes.
External Calibration
External calibration is generally performed with a high-precision calibrator
at either NI or a metrology lab. This procedure replaces all calibration
constants in the EEPROM and is equivalent to a factory calibration at NI.
Because the external calibration procedure changes all EEPROM
constants, it invalidates the original calibration certificate. If an external
calibration is done with a traceable signal generator source, a new
calibration certificate can be issued. This document describes specific
programming steps for writing an external calibration procedure for the
NI 9205/9206.
Software and Documentation Requirements
This section describes the software and documentation required for both
self-calibration and external calibration.
Software
Install NI-DAQmx 8.1 or later on the calibration computer. NI-DAQmx
includes high-level function calls to simplify the task of writing software to
calibrate devices. You must have the proper device driver installed on the
calibration system before calibrating the device.
Note NI recommends that you install the NI-DAQmx driver software before physically
installing the NI 9205/9206. NI-DAQmx, available at
and controls the NI 9205/9206.
NI-DAQmx supports a number of programming languages, including
LabVIEW, LabWindows
Visual Basic 6.0, Microsoft .NET, and Borland C++.
™
/CVI™, Microsoft Visual C++ 6.0, Microsoft
ni.com/downloads, configures
© National Instruments Corporation 3 NI 9205/9206 Calibration Procedure
Documentation
You can access the NI-DAQmx header file, NIDAQmx.h, like any standard
library. You can find examples of how to use the NI-DAQmx driver in the
Program Files\National Instruments\NI-DAQ\Examples
directory.
You might find the following documentation helpful as you write the
calibration procedure:
• NI-DAQmx Help—This help file contains general information about
measurement concepts, key NI-DAQmx concepts, and common
applications that apply to all programming environments. To access
this help file, select Start»All Programs»National Instruments»
NI-DAQ»NI-DAQmx Help.
• NI-DAQmx C Reference Help—This help file contains C reference and
general information about measurement concepts. To access this help
file, select Start»All Programs»National Instruments»NI-DAQ»
NI-DAQmx C Reference Help.
• DAQ Getting Started Guide for NI-DAQ 8.0 or later—This guide
describes how to install NI-DAQmx for Windows software and
NI-DAQmx-supported DAQ devices, and how to confirm that your
device is operating properly. To access this guide, select Start»
All Programs»National Instruments»NI-DAQ»DAQ Getting
Started Guide.
Note The documents above are installed with NI-DAQmx. You can also download the
latest versions from the NI Web site at
ni.com/manuals.
• NI 9205 Operating Instructions/NI 9206 Operating Instructions—
These documents contain information about specific device features.
The limits you use to verify the accuracy of the devices are based on
the specifications found in this document. You can download the latest
versions of these documents from the NI Web site at
manuals
.
ni.com/
NI 9205/9206 Calibration Procedure 4 ni.com
Calibration Requirements
Password
The default password for password-protected operations is NI.
Test Equipment
National Instruments recommends that you use the following equipment
for calibrating the NI 9205/9206:
• Fluke 5700A calibrator. If that instrument is unavailable, use a
high-precision voltage source with an accuracy of at least 10 ppm.
• NI cDAQ-9172 chassis.
Test Conditions
Follow these guidelines to optimize the connections and the environment:
• Keep connections to the device as short as possible. Long cables and
wires act as antennae, picking up extra noise that can affect
measurements.
• Use shielded copper wire for all cable connections to the device.
Use twisted-pair wire to eliminate noise and thermal offsets.
• Maintain an ambient temperature of 23 ±10 °C. The device
temperature will be greater than the ambient temperature.
• Keep relative humidity below 80%.
• Allow a warm-up time of at least 10 minutes to ensure that the
measurement circuitry is at a stable operating temperature.
Calibration Process
This section provides instructions for verifying and adjusting the
NI 9205/9206.
Calibration Process Overview
The calibration process consists of the following steps:
1. Initial Setup—Configure the device in NI-DAQmx.
2. Self-Calibration—Measure the onboard reference voltage of the
device and adjust the self-calibration constants.
3. Verification Procedure—Verify the existing operation of the device.
© National Instruments Corporation 5 NI 9205/9206 Calibration Procedure
This step confirms whether the device was operating within its
specified range prior to calibration.
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