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National Instruments 9205, Процедура калибровки

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©

 National Instruments Corporation

3

NI 9205/9206 Calibration Procedure

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 

ni.com/downloads

, configures 

and controls the NI 9205/9206.

NI-DAQmx supports a number of programming languages, including 
LabVIEW, LabWindows

™

/CVI

™

, Microsoft Visual C++ 6.0, Microsoft 

Visual Basic 6.0, Microsoft .NET, and Borland C++.

Содержание 9205

Страница 1: ... 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 fr...

Страница 2: ... 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 monos...

Страница 3: ...hanges 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 do...

Страница 4: ...t 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 Instrum...

Страница 5: ...ire 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 secti...

Страница 6: ...72 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 Sel...

Страница 7: ...fy all values although you can save time by verifying only the values used in your application 3 If you use C function calls create a task using DAQmxCreateTask as shown in the following table If you use LabVIEW skip this step The task is created in step 4 in LabVIEW Table 1 NI Connection Accessories Device Connection Accessory Connection Instructions NI 9205 9206 NI 9940 36 position strain relief...

Страница 8: ...x Timing VI as shown in the following table NI DAQmx Function Call LabVIEW Block Diagram Call DAQmxCreateAIVoltageChan with the following parameters taskHandle taskHandle physicalChannel dev1 ai0 nameToAssignToChannel myVoltageChannel terminalConfig DAQmx_Val_Cfg_Default minVal 10 0 maxVal 10 0 units DAQmx_Val_Volts customScaleName NULL NI DAQmx Function Call LabVIEW Block Diagram Call DAQmxCfgSam...

Страница 9: ... Task VI as shown in the following table 10 Repeat steps 3 through 9 for all ranges and all values 11 Disconnect the calibrator from the device or proceed to the Adjustment Procedure section to adjust the analog input calibration constants NI DAQmx Function Call LabVIEW Block Diagram CallDAQmxStartTask with the following parameter taskHandle taskHandle NI DAQmx Function Call LabVIEW Block Diagram ...

Страница 10: ...s adjusted by the metrology laboratory The default password is NI Complete the following steps to adjust the device with a calibrator 1 Refer to Table 1 for a list of the NI connection accessories for the NI 9205 9206 and instructions on connecting the calibrator to the device 2 Set the calibrator to output 4 0 V 3 Open a calibration session on the device using DAQmxInitExtCal DAQmx Initialize Ext...

Страница 11: ...ard memory Note If the device fails the calibration procedure no constants are written to the EEPROM 6 Disconnect the calibrator from the device The device is now calibrated with respect to the external source After calibrating the device verify the analog input operation by repeating the Verification Procedure section NI DAQmx Function Call LabVIEW Block Diagram Call DAQmxMSeriesCalAdjust with th...

Страница 12: ...0 4 0 2 114 10 4 0 1 Absolute accuracy values at full scale on the analog input channels assume the device is operating within 10 C of the last external calibration and are valid for averaging 100 samples immediately following internal calibration 2 Sensitivity is the smallest voltage change that can be detected It is a function of noise Table 3 Accuracy Details Nominal Range V Residual Gain Error...

Страница 13: ...ResidualAIGainError GainTempco TempChangeFromLastInternalCal ReferenceTempco TempChangeFromLastExternalCal OffsetError ResidualAIOffsetError OffsetTempco TempChangeFromLastInternalCal INL_Error Noise Uncertainty RandomNoise 3 for a coverage factor of 3 Σ and averaging 10000 points ResidualAIGainError ErrorRelativetoExternalRefppm ReferenceDriftOverTimeppm_per_year GainTempco AnalogCircuitryGainTem...

Страница 14: ... when the device is within its 2 year calibration interval the test point value should fall between these upper and lower limit values Table 4 NI 9205 9206 Analog Input Values Range V Test Point 2 Year Limits Minimum Maximum Location Value V Lower Limit V Upper Limit V 10 10 Max 9 980000 9 976836 9 983164 10 10 Mid 0 000000 0 001407 0 001407 10 10 Min 9 980000 9 983164 9 976836 5 5 Max 4 990000 4 ...

Страница 15: ...ruments 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 0 662 45 79 90 0 Belgium 32 0 2 757 00 20 Brazil 55 11...

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