National Instruments 9238 Calibration Manual
CALIBRATION PROCEDURE
NI 9238
4-Channel, ±0.5 V, 24-Bit Simultaneous, Channel-to-Channel Isolated
Analog Input Module
This document contains the verification and adjustment procedures for the NI 9238. For more
information about calibration solutions, visit
Contents
Software.................................................................................................................................... 1
Documentation.......................................................................................................................... 2
Test Equipment......................................................................................................................... 2
Test Conditions......................................................................................................................... 3
Initial Setup............................................................................................................................... 3
Verification ............................................................................................................................... 4
Accuracy Verification....................................................................................................... 4
Adjustment................................................................................................................................ 6
EEPROM Update ..................................................................................................................... 6
Reverification ........................................................................................................................... 7
Where to Go for Support .......................................................................................................... 7
ni.com/calibration.
Software
Calibrating the NI 9238 requires the installation of NI-DAQmx 14.1 or later on the calibration
system. You can download NI-DAQmx from ni.com/downloads. NI-DAQmx supports
LabVIEW, LabWindows™/CVI™, ANSI C, Microsoft Visual C++, Microsoft Visual Basic
.NET, and Microsoft Visual C#. When you install NI-DAQmx, you only need to install support
for the application software that you intend to use.
Documentation
Consult the following documents for information about the NI 9238, NI-DAQmx, and your
application software. All documents are available on
software.
NI cDAQ-9174/9178 Quick Start
NI-DAQmx installation and hardware setup
NI 9238 Operating Instructions and Specifications
NI 9238 specific information, specifications, and calibration interval
NI-DAQmx Readme
Operating system and application software support in NI-DAQmx
LabVIEW Help
LabVIEW programming concepts and reference information about NI-DAQmx
VIs and functions
ni.com and help files install with the
NI-DAQmx C Reference Help
Reference information for NI-DAQmx C functions and NI-DAQmx C properties
NI-DAQmx .NET Help Support for Visual Studio
Reference information for NI-DAQmx .NET methods and NI-DAQmx .NET
properties, key concepts, and mapping C enums to .NET enums
Test Equipment
Table 1 lists the equipment recommended for the performance verification and adjustment
procedures. If the recommended equipment is not available, select a substitute using the
requirements listed in Table 1.
Table 1. Recommended Equipment
Recommended
Equipment
Calibrator Fluke 5500A Use a high-precision voltage source with an accuracy
Model
Requirements
of ≤60 ppm and offset error ≤6µV.
Chassis NI cDAQ-9178 —
2 | ni.com | NI 9238 Calibration Procedure
Test Conditions
The following setup and environmental conditions are required to allow the NI 9238 to meet the
performance levels shown in Table 2:
• Keep connections to the NI 9238 as short as possible. Long cables and wires act as
antennas, picking up extra noise that can affect measurements.
• Verify that all connections to the NI 9238 are secure.
• Use shielded copper wire for all cable connections to the NI 9238. Use twisted-pairs wire
to eliminate noise and thermal offsets.
• Maintain an ambient temperature of 23 °C ± 5 °C.
• Keep relative humidity below 80%.
• Allow a warm-up time of at least 10 minutes to ensure that the NI 9238 measurement
circuitry is at a stable operating temperature.
Initial Setup
Refer to the NI cDAQ-9174/9178 Quick Start for information about how to install the software
and hardware and how to configure the device in Measurement & Automation Explorer (MAX).
Complete the following steps to set up the NI 9238.
1. Install NI-DAQmx.
2. Make sure the NI cDAQ-9178 power source is not connected.
3. Connect the NI cDAQ-9178 to the system safety ground.
a. Attach a ring lug to a 14 AWG (1.6 mm) wire.
b. Use the ground screw to connect the ring lug to the ground terminal on the side of the
NI cDAQ-9178.
c. Attach the other end of the wire to the system safety ground.
4. Install the module in slot 8 of the NI cDAQ-9178 chassis. Leave slots 1 through 7 of the
NI cDAQ-9178 chassis empty.
5. Connect the NI cDAQ-9178 chassis to your host computer.
6. Connect the power source to the NI cDAQ-9178 chassis.
7. Launch MAX.
8. Right-click the device name and select Self-Test to ensure that the module is working
properly.
NI 9238 Calibration Procedure | © National Instruments | 3
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