National Instruments cDAQ Manual

CALIBRATION PROCEDURE
NI cDAQ Chassis
This document contains information for calibrating the National Instruments cDAQ chassis. For more
information on calibration, visit ni.com/calibration.
Contents
Software Requirements........................................................................................................................ 1
Documentation Requirements.............................................................................................................. 1
Calibration Interval .............................................................................................................................. 2
Test Equipment .................................................................................................................................... 2
Test Conditions .................................................................................................................................... 2
Calibration Procedures......................................................................................................................... 2
Initial Setup.................................................................................................................................. 3
Verification .................................................................................................................................. 3
Where to Go for Support ..................................................................................................................... 4
Software Requirements
Calibrating the NI cDAQ chassis requires installing the latest NI-DAQmx driver on the calibration
system. You can download the NI-DAQmx instrument driver from ni.com/downloads. NI-DAQmx
supports programming an External Calibration in the LabVIEW, LabWindows™/CVI™, C/C++, C#, and
Visual Basic .NET. application development environments (ADEs). When you install NI-DAQmx, you
only need to install support for the ADE that you intend to use.
Documentation Requirements
For information about NI-DAQmx and NI cDAQ chassis, you can consult the following documents:
•DAQ Getting Started guides—These guides provide instructions for installing and configuring
NI-DAQ devices.
•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.
•NI-DAQmx C Reference Help—This help file contains C reference and general information about
measurement concepts.
The documents above are installed with NI-DAQmx. You also can find the latest versions of the
documentation at ni.com/manuals.
•NI cDAQ-91xx User Guide and Specifications—This document includes detailed information
about your NI cDAQ chassis and provides the published specification values for NI cDAQ chassis.
Refer to the most recent User Guide and Specifications online at ni.com/manuals for
specifications.
ni.com/manuals
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NI cDAQ Chassis Calibration Procedure 2 ni.com
•NI cDAQ-9188 Ethernet Chassis Quick Start—This document explains how to install the
application and NI-DAQmx driver software, set up your NI cDAQ-9188 Ethernet chassis and
I/O modules, confirm the system is operating properly, and take your first measurement. You can
find this document at ni.com/manuals.
Calibration Interval
National Instruments recommends a calibration interval of one year for the NI cDAQ chassis. Adjust the
recommended calibration interval based on the measurement accuracy demands of your application.
Test Equipment
National Instruments recommends that you use the equipment in Table 1 for calibrating an NI cDAQ
chassis.
Test Conditions
The following setup and environmental conditions are required to ensure the NI cDAQ chassis meets
published specifications.
• Keep connections to the C Series module as short as possible. Long cables and wires act as
antennae, picking up extra noise that can affect measurements.
• Maintain an ambient temperature of 23 ±5 °C. The device temperature will be greater than the
ambient temperature.
• Keep relative humidity below 90%.
• Allow a warm up time of at least 10 minutes to ensure that the measurement circuitry is at a stable
operating temperature.
Calibration Procedures
The calibration process includes the following steps:
1. Initial Setup—Install the device and configure it in Measurement & Automation Explorer (MAX).
2. Verification—Verify the existing operation of the device. This step confirms whether the device is
operating within the published specifications prior to adjustment.
3. Adjustment—If the device does not fall within the desired specifications, return the device to NI for
repair. Refer to Where to Go for Support for assistance in returning the chassis to NI.
4. Reverification—Repeat the verification procedure to ensure that the device is operating within the
published specifications after adjustment.
The first two procedures are described in more detail in the following sections.
Table 1. Recommended Equipment
Equipment Recommended Model Minimum Requirements
Counter Agilent 53131A If this instrument is unavailable, use a
counter accurate to ±5 ppm.
C Series Digital I/O Module NI 9401 or NI 9402 —
C Series Connection Accessory NI 9934 (NI 9401) 25-pin DSUB connector kit.

©National Instruments Corporation 3 NI cDAQ Chassis Calibration Procedure
Initial Setup
Refer to the DAQ Getting Started guides for instructions on installing the software, hardware, and
configuring the NI cDAQ chassis. NI cDAQ-9188 users should refer to the NI cDAQ-9188 Ethernet
Chassis Quick Start.
Verification
This section provides instructions for verifying the counter on an NI cDAQ chassis.
1. Connect the counter to the C Series digital I/O module. Refer to Figure 1 for a connection diagram
of the NI 9401 and NI 9402.
a. Connect the positive input of the counter to DIO 0 on the C Series module.
b. Connect the negative input of the counter to COM or GND on the C Series module.
Figure 1. NI 9401 and NI 9402 Pin Assignments
2. Create and configure a counter output channel according to Table 2.
3. Start the generation of a square wave.
4. Configure the counter to measure frequency and use a 1 MΩ impedance.
5. Take a measurement of the square wave.
6. Compare the counter reading to the limits in Table 3.
Table 2. Counter Output Configuration
Frequency
Scaled
Units
Idle
State
Initial
Delay
DAQmx Timing
Instance
Generation
Mode
Samples to
Write
5000000 Seconds Low 0Implicit Continuous
Pulses
1000
Table 3. NI cDAQ Chassis Counter Limits
Set Point (MHz) Lower Limit (MHz) Upper Limit (MHz)
5 4.99975 5.00025
COM
NC
COM
COM
NC
COM
COM
NC
COM
COM
NC
COM
COM
DIO0
NC
DIO1
DIO2
NC
DIO3
DIO4
NC
DIO5
DIO6
NC
DIO7
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25 DIO 3
GND
DIO 2
GND
DIO 0
NI 9402NI 9401
GND
DIO 1
GND

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National Instruments products/technology, refer to the appropriate location: Help»Patents in your
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ni.com/patents.
© 2010 National Instruments Corporation. All rights reserved. 373718A-01 Oct10
7. Stop the generation.
8. Clear the generation.
9. Disconnect the counter from the C Series module.
The counter on the NI cDAQ chassis is now verified.
Where to Go for Support
The National Instruments Web site is your complete resource for technical support. At ni.com/
support you have access to everything from troubleshooting and application development self-help
resources to email and phone assistance from NI Application Engineers.
National Instruments corporate headquarters is located at 11500 North Mopac Expressway, Austin,
Texas, 78759-3504. National Instruments also has offices located around the world to help address
your support needs. For telephone support in the United States, create your service request at
ni.com/support and follow the calling instructions or dial 512 795 8248. For telephone support
outside the United States, contact your local branch office:
Australia 1800 300 800, Austria 43 662 457990-0, Belgium 32 (0) 2 757 0020,
Brazil 55 11 3262 3599, Canada 800 433 3488, China 86 21 5050 9800,
Czech Republic 420 224 235 774, Denmark 45 45 76 26 00, Finland 358 (0) 9 725 72511,
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Italy 39 02 41309277, Japan 0120-527196, Korea 82 02 3451 3400, Lebanon 961 (0) 1 33 28 28,
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