National Instruments 9235 Скачать руководство пользователя страница 5 | Manualshive

Страница: 5 / 20

National Instruments 9235 Скачать руководство пользователя страница 5

©

National Instruments Corporation

5

NI 9235/9236 Calibration Procedure

Calibration Procedure

This section provides instructions for verifying the performance of the
NI 9235/9236.

Calibration Process Overview

The calibration process consists of the following steps:

1.

Initial Setup

—Configure the device in NI-DAQmx.

2.

Verification Procedures

—Verify the existing operation of the device.

This step confirms whether the device is operating within its specified
range and whether it needs adjustment.

3.

Adjustment

—If the device does not fall within the desired

specifications, submit the device to NI for a factory calibration to
adjust the calibration constants.

4.

Verification Procedures

—Perform another verification to ensure that

the device operates within its specifications after adjustment.

The first two steps are explained in the following sections.

Initial Setup

You must configure the device in Measurement & Automation Explorer
(MAX) to communicate with NI-DAQmx.

Complete the following steps to configure a device in MAX:

1.

Install the NI-DAQmx driver software.

2.

Make sure that no power is connected to the module terminals. If the
system is in a nonhazardous location, the chassis power can be on
when you install the module.

3.

Insert the module into an available slot in the cDAQ chassis.

4.

Launch MAX.

5.

Right-click the device name and select

Self-Test

to ensure that the

device is working properly.

Note

When a device is configured with MAX, it is assigned a device name. Each function

call uses this device name to determine which DAQ device to calibrate. This document uses

dev1

to refer to the device name. In the following procedures, use the device name as it

appears in MAX.

«
...
3
4
5
6
7
...
»

Содержание 9235

Страница 1: ...ions You can install these help files when you install NI DAQmx on the calibration computer Contents Conventions 2 Software 2 Documentation 3 Calibration Interval 3 Test Equipment 4 Test Conditions 4 Calibration Procedure 5 Calibration Process Overview 5 Initial Setup 5 Connecting the Calibrator to the Module 6 Verification Procedures 8 Measurement Accuracy Verification 8 Shunt Calibration Accurac...

Страница 2: ...his font is also used for the proper names of disk drives paths directories programs subprograms subroutines device names functions operations variables filenames and extensions monospace italic Italic text in this font denotes text that is a placeholder for a word or value that you must supply Software Install NI DAQmx 8 8 or later on the calibration computer NI DAQmx includes high level function...

Страница 3: ...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 9235 9236 Operating Instructions and Specifications This document describes how to use the NI 9235 9236 and includes specif...

Страница 4: ...t 10 minutes to ensure that the measurement circuitry is at a stable operating temperature Table 1 Recommended Equipment Equipment Recommended Model Requirements Calibrator Fluke 5500A If this instrument is unavailable use a calibrator with generation of resistances in the ranges of 108 Ω 132 Ω and 315 Ω 385 Ω with 0 01 Ω resolution an accuracy of at least 90 ppm and automatic lead wire compensati...

Страница 5: ...e operates within its specifications after adjustment The first two steps are explained in the following sections Initial Setup You must configure the device in Measurement Automation Explorer MAX to communicate with NI DAQmx Complete the following steps to configure a device in MAX 1 Install the NI DAQmx driver software 2 Make sure that no power is connected to the module terminals If the system ...

Страница 6: ... the module channel you want to verify Leave all other channels unconnected Note The three connections to the calibrator LO terminal must be connected at the calibrator output jack Note Ensure that the connection resistance between the calibrator LO terminal and the module RC terminal meets the requirement listed in Table 1 4 Connect the HI terminal of the calibrator to the EXC0 terminal of the mo...

Страница 7: ...ator to Module Connections Refer to Figure 2 for the terminal assignments of the NI 9235 9236 Figure 2 NI 9235 9236 Terminal Assignments Fluke 5500A AUX HI EXC1 EXC0 AI0 RC0 AUX LO HI LO NI 9235 9236 EXC0 AI0 RC0 EXC2 AI2 RC2 EXC4 AI4 RC4 EXC6 AI6 RC6 EXC1 AI1 RC1 EXC3 AI3 RC3 EXC5 AI5 RC5 EXC7 AI7 RC7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 ...

Страница 8: ...ed test coverage You can verify the following for NI 9235 9236 modules measurement accuracy shunt calibration accuracy excitation voltage Measurement Accuracy Verification Complete the following steps to test the measurement accuracy of the device 1 Zero the calibrator with the ohms only zero OHMS ZERO operation Refer to the calibrator documentation for more information about zeroing the calibrato...

Страница 9: ...or the correct instance to use for polymorphic VIs LabVIEW Block Diagram NI DAQmx Function Call LabVIEW does not require this step Call DAQmxCreateTask with the following parameters taskName AIVerificationTask taskHandle taskHandle LabVIEW Block Diagram NI DAQmx Function Call Call DAQmxCreateAIVoltageChan WithExcit with the following parameters taskHandle taskHandle physicalChannel dev1 aix nameTo...

Страница 10: ... Start Task VI as shown in the following table LabVIEW Block Diagram NI DAQmx Function Call CallDAQmxCfgSampClkTiming with the following parameters taskHandle taskHandle source NULL rate 5000 sampleMode DAQmx_Val_FiniteSamps sampsPerChan 5000 LabVIEW Block Diagram NI DAQmx Function Call Call DAQmxSetAIBridgeShuntCal Enable with the following parameters taskHandle taskHandle channel NULL data FALSE...

Страница 11: ...es although you can save time by verifying only the values used in your application 14 Perform the following calculation for each test result value other than 0 V V using the results you recorded in step 11 Test Result 0 V V Test Result LabVIEW Block Diagram NI DAQmx Function Call Call DAQmxReadAnalogF64 with the following parameters taskHandle taskHandle numSampsPerChan 1 timeout 10 0 fillMode DA...

Страница 12: ...e DMM and 4 wire resistance measurement connections measure the resistance of the wire to be connected between the calibrator LO terminal and the module RC terminal and record the result for later use You must do this because this connection to the module creates a lead wire desensitization error This results in module readings that are systematically lower than the true shunt calibration output K...

Страница 13: ...or the correct instance to use for polymorphic VIs LabVIEW Block Diagram NI DAQmx Function Call LabVIEW does not require this step Call DAQmxCreateTask with the following parameters taskName SCVerificationTask taskHandle taskHandle LabVIEW Block Diagram NI DAQmx Function Call Call DAQmxCreateAIVoltageChan WithExcit with the following parameters taskHandle taskHandle physicalChannel dev1 aix nameTo...

Страница 14: ... Start Task VI as shown in the following table LabVIEW Block Diagram NI DAQmx Function Call CallDAQmxCfgSampClkTiming with the following parameters taskHandle taskHandle source NULL rate 5000 sampleMode DAQmx_Val_FiniteSamps sampsPerChan 10000 LabVIEW Block Diagram NI DAQmx Function Call Call DAQmxSetAIBridgeShuntCal Enable with the following parameters taskHandle taskHandle channel NULL data FALS...

Страница 15: ...following calculation using the results you recorded in step 11 ResultSCE ResultSCD 1 Rwire Rcomp where ResultSCE result with shunt calibration enabled ResultSCD result with shunt calibration disabled Rwire wire resistance measured in step 1 Rcomp 120 Ω for the NI 9235 and 350 Ω for the NI 9236 LabVIEW Block Diagram NI DAQmx Function Call Call DAQmxReadAnalogF64 with the following parameters taskH...

Страница 16: ...BY 18 Disconnect the calibrator from the device Excitation Voltage Verification The excitation source of the NI 9235 9236 is common to all eight input channels so you need to verify excitation voltage on only one channel Complete the following steps to verify the excitation voltage 1 Connect the positive input of the DMM to any EXC terminal of the module and the negative input of the DMM to any RC...

Страница 17: ...owing calibration specifications are for 23 5 C Table 2 NI 9235 9236 Measurement Accuracy Module Percent of Reading Gain Error Percent of Range Offset Error NI 9235 9236 0 04 max 0 002 max Range equals 29 4 mV V Table 3 NI 9235 9236 Shunt Calibration Accuracy Module Percent of Reading Gain Error NI 9235 0 22 max NI 9236 0 20 max Table 4 NI 9235 9236 Excitation Voltage Accuracy Module Accuracy NI 9...

Страница 18: ...For accuracy verification Upper Limits and Lower Limits are given in units of V V for verification and units of με for reference Table 5 NI 9235 Measurement Accuracy Verification Test Limits Calibrator Output Ω Nominal Value V V Nominal Value με 1 Year Limits Lower Limit V V Upper Limit V V Lower Limit με Upper Limit με 120 0 0 108 0 0263158 50 000 0 0263048 0 0263268 49 980 1 50 019 9 114 0 01282...

Страница 19: ...25 011 3 385 0 0238095 50 000 0 0237995 0 0238195 49 977 8 50 022 1 Note The Upper and Lower Limit V V values are commonly used for verification The Upper and Lower Limit με values are for reference Table 7 NI 9235 9236 Shunt Calibration Accuracy Verification Test Limits Module Nominal Value μV V Nominal Value με 1 Year Limits Lower Limit μV V Upper Limit μV V Lower Limit με Upper Limit με NI 9235...

Страница 20: ...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 suppor...

Отзывы:

Нет отзывов