National Instruments Module SCXI-1503 Manual

CALIBRATION PROCEDURE
SCXI -1503
This document contains information for verifying and adjusting the SCXI-1503 module using
NI-DAQmx 8.1 or later. For more information about calibration, visit ni.com/calibration.
Contents
Software Requirements........................................................................................................................ 1
Documentation Requirements.............................................................................................................. 2
Calibration Interval .............................................................................................................................. 2
Test Equipment .................................................................................................................................... 3
Test Conditions .................................................................................................................................... 3
Calibration Procedures......................................................................................................................... 4
Initial Setup.................................................................................................................................. 5
Self-Calibration............................................................................................................................ 8
MAX .................................................................................................................................... 8
Verification .................................................................................................................................. 8
Verifying the Analog Input.................................................................................................. 8
Verifying the Excitation Current ......................................................................................... 11
Adjustment................................................................................................................................... 11
Adjusting the Analog Input.................................................................................................. 12
Adjusting the Excitation Current ......................................................................................... 14
Where to Go for Support ..................................................................................................................... 15
Software Requirements
Calibrating the SCXI-1503 requires installing NI-DAQmx 8.1 or later on the calibration system.
You can download NI-DAQmx from ni.com/downloads. NI-DAQmx 8.1 or later supports
self-calibration and external calibration in the LabVIEW, LabWindows/CVI, C/C++, C#, and
Visual Basic .NET application development environments (ADEs). When you install NI-DAQmx 8.1 or
later, you only need to install support for the ADE that you intend to use.
™
ni.com/manuals
DeutschFrançais

SCXI-1503 Calibration Procedure 2 ni.com
Documentation Requirements
For information about NI-DAQmx, and the SCXI-1503 module and SCXI-1306 terminal block, consult
the following documents:
•SCXI Quick Start Guide—provides instructions for installing and configuring SCXI chassis and
modules.
•SCXI-1503 User Manual (includes specifications)—includes detailed information and published
specifications for the SCXI-1503.
•SCXI-1306 Terminal Block Installation Guide—includes detailed information and published
specifications for the SCXI-1306.
•NI-DAQmx Help—includes information about creating applications that use NI-DAQmx.
•NI-DAQmx C Reference Help—includes information about the functions in the driver.
You can find the latest versions of the documentation at ni.com/manuals.
Calibration Interval
National Instruments recommends a calibration interval of one year for the SCXI-1503. You should
adjust the recommended calibration interval based on the measurement accuracy demands of your
application.

©National Instruments 3 SCXI-1503 Calibration Procedure
Test Equipment
National Instruments recommends using the equipment in Table 1 for adjusting and verifying the
SCXI-1503.
Test Conditions
The following setup and environmental conditions are required to ensure the SCXI-1503 meets
published specifications.
• Keep connections to the module as short as possible. Long cables and wires act as antennae, which
can pick up extra noise that affects measurements.
• Verify that all connections to the calibration system are secure.
• Maintain an ambient temperature of 25 ±10 °C. The SCXI-1503 module temperature will be
greater than the ambient temperature. If you plan to operate the SCXI-1503 at a specific
temperature outside this range, calibrate the module at that temperature.
• Keep relative humidity below 80%.
Table 1. Recommended Equipment
Equipment
Recommended
Model
Parameter
Measured Minimum Requirements
Calibrator Fluke 5500A* Analog Input If this instrument is
unavailable, use a
calibrator that is accurate to
10 ppm (5 digits).
DMM PXI-4071 Excitation Current
Analog Input
If this instrument is
unavailable, use a
multiranging 7½ digit
DMM.
SCXI Chassis SCXI-1000 — —
DAQ Device NI PCI(e)/PXI(e) E, M
or X Series Device
—16-bit DAQ device
that is supported by
NI-DAQmx 8.1 or later.
Terminal Block Connection
Accessory
SCXI-1306 — —
Rear Connection Accessory SCXI-1349 — —
Terminal Accessory, 50-pin CB-50 — —
Ribbon Cable, 50-Pin NB1 — —
Cable between SCXI-1349
and E Series DAQ devices
SH68-68-EP — —
Cable between SCXI-1349
and M Series or X Series
DAQ devices
SHC68-68-EPM — —
* If using the Fluke 5500A calibrator, you must have the Fluke Fl5xmcal driver installed on the test computer.

SCXI-1503 Calibration Procedure 4 ni.com
• Allow a warm-up time of at least 30 minutes to ensure that the measurement circuitry is at a stable
operating temperature.
• Use shielded copper wire for all cable connections to the SCXI-1306 terminal block. Use
twisted-pair wire to eliminate noise and thermal offsets.
• Ensure that the SCXI chassis empty slots contain front and rear filler panels.
• Plug the SCXI chassis, computer, and the instrument standard into the same power strip to avoid
ground loops.
Calibration Procedures
The calibration process includes the following steps:
1. Initial Setup—Install the module and configure it in Measurement & Automation Explorer (MAX).
2. Self-Calibration—Adjust the self-calibration constants of the module.
3. Verification—Verify the existing operation of the module. This step confirms whether the module
is operating within the published specifications prior to adjustment.
4. Adjustment—Adjust the calibration constants of the module. The adjustment procedure
automatically stores the calibration date on the EEPROM. Go to ni.com/calibration for
information about returning a module to NI for a factory calibration.
5. Reverification—Repeat the verification procedure to ensure that the module is operating within the
published specifications after adjustment.
These procedures are described in more detail in the following sections.

©National Instruments 5 SCXI-1503 Calibration Procedure
Initial Setup
Refer to the DAQ Getting Started Guides and the SCXI Quick Start guide for information about how to
install the software and hardware, and how to configure the module in MAX. Figure 1 shows a typical
SCXI setup for calibration using an NI PCI(e) DAQ device.
Figure 1. Typical Setup for Verification and Adjustment Using an NI PCI(e) DAQ Device
1 SCXI-1306 Terminal Block
2 SCXI-1503 Module
3 SCXI-1000 Chassis
4 SCXI-1349 Adapter
5 SH68-68 EP Cable (for E Series DAQ Device)
SHC68-68 EPM Cable (for M or X Series DAQ Device)
6 Test Computer, with NI PCI(e) DAQ Device
7DMM
8Calibrator
9 Calibrator to SCXI-1306 Wiring
10 CB-50 to DMM Wiring
11 CB-50 Terminal Accessory
12 NB1 Ribbon Cable
+10.0000208 V
+10.0000001 V DC
,
DCV ACVOHM DCI ACI FREQ
Local




Auto
Cal
Auto
Zero
Trig
Recall
State
NPLC
Offset
Comp
NRdg/
Trig
Store
State
On
Off
7.000
kHz
7
10
SCXI 1100
2468 1012 14 16 18 20 20 24 26 28 30 32 34 36 38 40 42 44 46 48 50
13 5 7 911131517 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
1
2
8
®
5
4
3
2
1
ADDRESS
3
9
4
6
11
12
5

SCXI-1503 Calibration Procedure 6 ni.com
Figure 2 shows a typical SCXI setup for calibration using the NI PXI(e) DAQ device.
Figure 2. Typical Setup for Verification and Adjustment Using an NI PXI(e) DAQ Device
1. Power off the SCXI-1000 chassis.
2. Insert the SCXI-1503 into any available SCXI-1000 chassis slot.
Note If you are using an NI PCI(e) DAQ device, connect the SCXI-1349 to the NI PCI(e) DAQ
device using an SHC68-68 cable.
Note If you are using an NI PXI(e) DAQ device rather than an NI PCI(e) DAQ device, refer to
Figure 2 to make your connections.
1 SCXI-1306 Terminal Block
2 SCXI-1503 Module
3 SCXI-1000 Chassis
4 SCXI-1349 Adapter
5 SHC68-68 EPM Cable
6 PXI Chassis
7DMM
8 Calibrator
9 Calibrator to SCXI-1306 Wiring
10 CB-50 to DMM Wiring
11 CB-50 Terminal Accessory
12 NB1 Ribbon Cable
+10.0000208 V
+10.0000001 V DC
,
DCVACV OHMDCIACIFREQ
Local




Auto
Cal
Auto
Zero
Trig
Recall
State
NPLC
Offset
Comp
NRdg/
Trig
Store
State
On
Off
7.000
kHz
SCXI 1100
2468101214 16 18 20 20 24 26 28 30 32 34 36 38 40 42 44 46 48 50
13 5 7 911 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
1
2
7
5
8
3
9
10
4
11
NI PXIe-1062Q
5
4
3
2
1
ADDRESS
12
6
NATIONAL
INSTRUMENTS

©National Instruments 7 SCXI-1503 Calibration Procedure
3. Ensure that all of the SCXI-1306 configuration switches are switched to the off position, as shown
in Figure 3.
Figure 3. SCXI-1306 Switch Diagram
4. Install the SCXI-1306 on the SCXI-1503 DUT.
5. Power on the SCXI-1000 chassis.
1 Configuration Switches (shown in Off position) 2 Switch Legends 3 Ground Lug
1 2 1 1 2 1
ON = Closed
IEX+/AI+ IEX–/AI–
Ch X
IEX+
AI+
AI–
IEX–
IEX+
AI+
AI–
IEX–
CH 0CH 1 CH 2CH 3 CH 4CH 5 CH 6CH 7
CH 9CH 8
CH 11CH 10
CH 13CH 12
CH 15CH 14
1 2 34 5 6 7 81 2 34 5 6 7 8
CH 4 CH 5 CH 6 CH 7CH 0 CH 1 CH 2 CH 3CH 12 CH 13CH 14 CH 15
CH 8CH 9 CH 10 CH 11
ON ON
SW 1 SW 2 ON ON SW 3SW 4
1
1 2 34 5 6 7 81 2 34 5 6 7 8
3
1 2 34 5 6 7 8
CH 0 CH 1 CH 2 CH 3
ON

SCXI-1503 Calibration Procedure 8 ni.com
Self-Calibration
The SCXI-1503 includes precise internal circuits and references used during self-calibration to adjust
for any errors caused by short-term fluctuations in the environment.
Note Allow a 30 minute warm-up period before you begin self-calibration.
You can initiate self-calibration from MAX.
MAX
To initiate self-calibration from MAX, complete the following steps:
1. Launch MAX.
2. Select My System»Devices and Interfaces»NI-DAQmx Devices.
Note NI-DAQmx Devices is not displayed when using NI-DAQmx 9.0 or later.
3. Select the DAQ device you are using to digitize the SCXI-1503.
4. Initiate self-calibration in one of the following ways:
•ClickSelf-Calibrate in the upper right corner of the window. If the Self-Calibrate button is
not displayed, click the »button.
• Right-click the module and select Self-Calibrate from the context menu.
5. Select the chassis containing the module you want to calibrate.
6. Select the module that you want to calibrate.
7. Initialize a self-calibration of the module you want to calibrate.
Verification
This section provides instructions for verifying the following SCXI-1503 specifications:
• Analog input.
• Excitation current.
Note Limits in Table 2 are based on the March 2007 edition of the SCXI-1503 User Manual, which
includes the specifications. Refer to ni.com/manuals to determine if there is a more recent edition
of the specifications. If a more recent edition of the specifications is available, recalculate the limits
based upon the latest specifications.
Verifying the Analog Input
Complete the following steps to verify the analog input of the SCXI-1503:
1. Connect the calibrator ± output to all of the SCXI-1306 AI± input channels.
Note Ensure that all switches on the SCXI-1306 are in the off position as shown in Figure 3.
2. Insert the NB1 ribbon cable into the breakout connector on the SCXI-1349.
3. Insert the SCXI-1349 into the SCXI-1503 rear connector.
4. Insert the other end of the NB1 ribbon cable into the CB-50 ribbon cable connector.

©National Instruments 9 SCXI-1503 Calibration Procedure
5. Connect the DMM V+ to pin 3 and DMM V- to pin 4 of the CB-50 terminal accessory. Refer to
Figure 4 for pin locations.
Figure 4. CB-50 Terminal Accessory Wiring Diagram for Connection to DMM
6. Configure an AI voltage channel with an input range of ±10 V for channel ai0 on the
NI PCI(e)/PXI(e) DAQ device.
7. Use DAQmx properties to read the AI dev scaling coefficients of the DAQ device. E Series have
two scaling coefficients while M Series and X Series have four scaling coefficients. Record the
first two scaling coefficients and save the values as a0and a1.
Note The DAQ device scaling coefficients, a0and a1, are the same for each channel on the SCXI
module since the DAQ device multiplexes all SCXI channels to channel ai0 on the DAQ device.
8. Clear the task.
1 To DMM V+
2 To DMM V-
3 NB1 Ribbon Cable Connector
4 CB-50 Top View
5 CB-50 Side View
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5
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SCXI-1503 Calibration Procedure 10 ni.com
9. Configure the calibrator to output a DC voltage. Table 2 shows the test point values.
10. Create an AI voltage channel with an input range of ±10 V for one channel on the SCXI-1503.
11. Configure the SCXI-1503 input channel for a finite acquisition with a sample rate of 1000 Hz and
1000 samples per channel.
12. Use DAQmx properties to set a gain of 1.
13. Use DAQmx properties to read the DAQ device scaling coefficients. E Series have two scaling
coefficients while M Series and X Series have four scaling coefficients. Record the first two scaling
coefficients and save the values as b0and b1.
14. Start the task to set the channel MUX to the specified channel.
15. Use the saved device scaling coefficients from the DAQ device, a0and a1from step 7, and the
combined DAQ device and SCXI-1503 module, b0and b1from step 13, to compute the device
scaling coefficients for just the SCXI-1503, c0and c1.
16. Configure the DMM to measure voltage at the CB-50 outputs and take a measurement.
Table 2. Test Point and Limit
SCXI-1503 Gain Test Point Level (V) Lower Limit (V) Upper Limit (V)
1 9 8.991680513 9.008319487
65.993900513 6.006099487
32.996120513 3.003879487
0-0.001659487 0.001659487
-3 -3.003879487 -2.996120513
-6 -6.006099487 -5.993900513
-9 -9.008319487 -8.991680513
100 0.09 0.089898305 0.090101695
0.06 0.059920505 0.060079495
0.03 0.029942705 0.030057295
0-0.0000350949 0.0000350949
-0.03 -0.030057295 -0.029942705
-0.06 -0.060079495 -0.059920505
-0.09 -0.090101695 -0.089898305
c0b0b1
a1
-----– a0 =
c1b1
a1
-----=

©National Instruments 11 SCXI-1503 Calibration Procedure
17. Apply the calculated scaling coefficients, c0and c1to the DMM measurement using the following
formula:
18. Compare the average scaled DMM reading with the test limit shown in Table 2.
19. Stop and then clear the DAQmx task.
20. Repeat steps 9 through 19 for each test point.
21. Repeat steps 9 through 20 with an input range of ±100 mV and a gain of 100.
Note The combined DAQ/SCXI-1503 scaling coefficients, b0and b1, will not change for each test
point, but each channel and gain will have different scaling coefficients. Recalculate c0and c1each
time a channel and/or gain changes.
22. Repeat steps 9 through 21 for the remaining channels.
Verifying the Excitation Current
Complete the following steps to verify the excitation current of the SCXI-1503:
1. Connect IEXx+ and IEXx- to the DMM current input where xis a channel value from 0 to 15.
Note Ensure that all switches on the SCXI-1306 are in the off position as shown in Figure 3.
2. Configure the DMM to do a current measurement with a range of 100 A and an accuracy of 15 nA
or better at 100 A.
Note The PXI-4071 can measure up to 105 A in the 100 A range.
3. Create an AI voltage channel and configure it to use internal excitation by setting the AI.Excit.Src
to internal and then read the excitation current value from the AI.Excit.Val property node. Save this
value to DUT IEX.
4. Configure the DMM to get current measurement results. Save this value to DMM Reading.
5. Calculate the excitation error using the following formula:
6. Compare the calculated excitation error with the limit IEx Accuracy = ±0.05%.
7. Clear the DAQmx task.
8. Repeat steps 1 through 7 to verify all other channels.
Adjustment
Following the adjustment procedure automatically updates the calibration date and temperature in the
EEPROM of the SCXI-1503.
Note National Instruments recommends a complete adjustment of your module to renew the
calibration interval. However, if you do not want to perform an adjustment, you can update the
calibration date and onboard calibration temperature without making any adjustments by calling only
the DAQmx Initialize External Calibration and DAQmx Close External Calibration VIs.
Adjustment corrects the following SCXI-1503 specifications:
• Analog input.
• Excitation current.
Scaled DMM Reading DMM Reading c1 c0 +=
IEx Accuracy DUT IEx
DMM Reading
----------------------------------- 1–


100=

SCXI-1503 Calibration Procedure 12 ni.com
Adjusting the Analog Input
Complete the following steps to adjust the analog input of the SCXI-1503:
1. Connect the calibrator output to all of the input channels on the SCXI-1306.
Note Ensure that all switches on the SCXI-1306 are in the off position as shown in Figure 3.
2. Insert the NB1 ribbon cable into the breakout connector on the SCXI-1349.
3. Insert the SCXI-1349 into the SCXI-1503 rear connector.
4. Insert the other end of the NB1 ribbon cable into the CB-50 ribbon cable connector.
5. Connect the DMM V+ to pin 3 and DMM V- to pin 4 of the CB-50 terminal accessorys. Refer to
Figure 5 for pin locations.
Figure 5. CB-50 Terminal Accessory Wiring Diagram for Connection to DMM
Note When MAX configures a module, it is assigned a module name. Each function call uses this
module name to determine the correct module to adjust. This document uses Dev1 when referring to
the module name. When you calibrate your module, use the module name assigned to it by MAX.
1 To DMM V+
2 To DMM V-
3 NB1 Ribbon Cable Connector
4 CB-50 Top View
5 CB-50 Side View
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©National Instruments 13 SCXI-1503 Calibration Procedure
6. Configure the calibrator to send out a DC voltage. Table 3 shows the test point.
7. Use the DAQmx Initialize External Calibration VI to create a calibration task.
8. Use the DAQmx Setup SCXI Calibration VI to configure the input channel.
9. Configure the DMM to measure voltage at the CB-50 outputs and take a measurement.
Table 3. DC Source
SCXI-1503 Gain Tes t Vol t age
19.1 V
6.1 V
3.1 V
0V
-3.1 V
-6.1 V
-9.1 V
100 0.091 V
0.061 V
0.031 V
0V
-0.031 V
-0.061 V
-0.091 V
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxInitExtCal with the
following parameters:
deviceName: Dev1
password: NI or SCXI (default)
calHandle: &calHandle
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxSetup1503Cal with
the following parameters:
calHandle: calHandle
channelName: Dev1/aix, where x
refers to the channel number
gain: 1

SCXI-1503 Calibration Procedure 14 ni.com
10. Use the DAQmx Adjust SCXI Calibration VI to calculate and store the constants.
11. Use the DAQmx Close External Calibration VI to commit the constant overwritten.
12. Repeat steps 6 through 11 for all SCXI-1503 channels.
13. Repeat steps 6 through 12 to test all test points for gain = 1.
14. Repeat steps 7 through 13 using a gain of 100 on the SCXI-1503.
15. Self-calibrate the SCXI-1503.
Adjusting the Excitation Current
Complete the following steps to adjust the excitation current of the SCXI-1503:
1. Connect IEXx+ and IEXx- to DMM current input with xbeing the number of the channel from
0to15.
Note Ensure that all switches on the SCXI-1306 are in the off position as shown in Figure 3.
2. Configure the DMM to do a current measurement with a range of 100 A and an accuracy of 15 nA
or better at 100 A.
Note The PXI-4071 can measure up to 105 A in the 100 A range.
3. Take a current measurement using the DMM. Save this value to DMM Reading.
4. Use the DAQmx Initialize External Calibration VI to create a calibration task.
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxAdjust1503Cal with
the following parameters:
calHandle: calHandle
refVoltage: test point sent out by the
calibrator.
measOutput: DMM measurement
result in step 9.
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxCloseExtCal with the
following parameters:
calHandle: calHandle
action: DAQmx_Val_Action_
commit
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxInitExtCal with the
following parameters:
deviceName: Dev1
password: NI or SCXI
calHandle: &calHandle

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5. Use the DAQmx Adjust SCXI Calibration VI and select 1503 Current to store the excitation current
constant.
6. Use the DAQmx Close External Calibration VI to commit the constant overwritten.
7. Repeat steps 1 through 6 for all of the other channels.
8. Once you have completed adjusting the SCXI-1503, reverify the module.
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, visit the Worldwide Offices section of ni.com/niglobal to access the branch office
Web sites, which provide up-to-date contact information, support phone numbers, email addresses, and
current events.
LabVIEW Block Diagram NI-DAQmx Function Call
Call
DAQmxAdjust1503CurrentCal
with the following parameters:
calHandle: calHandle
channelName: Channel under test
measOutput: Result from DMM in
step 3.
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxCloseExtCal with the
following parameters:
calHandle: calHandle
action:
DAQmx_Val_Action_commit