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National Instruments Corporation

3

SCXI-1120/D Calibration Procedure

Test Conditions

Follow these guidelines to optimize the connections and environment
during calibration:

Keep connections to the SCXI-1120/D module short. Long cables and
wires act as antennae, picking up extra noise and thermal offsets that
can affect measurements.

Use shielded copper wire for all cable connections to the device.
Use twisted-pair wire to eliminate noise and thermal offsets.

Maintain the temperature between 18–28 °C.

Keep relative humidity below 80%.

Allow a warm-up time of at least 15 minutes for the SCXI-1120/D
module to ensure the measurement circuitry is at a stable operating
temperature.

Calibration

The calibration procedure for the SCXI-1120/D module consists of the
following steps:

1.

Set up the module for testing.

2.

Verify the existing operation of the module to determine whether it is
operating within its specifications.

3.

Adjust the module with respect to a known voltage source.

4.

Verify that the module is operating within its specifications after
adjustments.

Summary of Contents for SCXI-1120/D

Page 1: ...factory specifications During calibration you supply and read voltage levels using external standards then you adjust the module calibration circuitry This circuitry compensates for any inaccuracies in the module and returns the accuracy of the module to the factory specifications Why Should You Calibrate The accuracy of electronic components drifts with time and temperature which can affect measu...

Page 2: ...not available use the accuracy requirements listed previously to select substitute calibration instruments Connectors If you do not have custom connection hardware you need the following connectors Terminal block such as the SCXI 1320 Shielded 68 pin connector cable 50 pin ribbon cable 50 pin breakout box SCXI 1349 adapter These components give easy access to the individual pins on the SCXI 1120 D...

Page 3: ...inate noise and thermal offsets Maintain the temperature between 18 28 C Keep relative humidity below 80 Allow a warm up time of at least 15 minutes for the SCXI 1120 D module to ensure the measurement circuitry is at a stable operating temperature Calibration The calibration procedure for the SCXI 1120 D module consists of the following steps 1 Set up the module for testing 2 Verify the existing ...

Page 4: ...p the SCXI 1120 D module for verification 1 Remove the grounding screw from the module 2 Remove the cover on the module to access the potentiometers Figure 1 Grounding Screw and Module Cover Removal 3 Remove the side plate of the SCXI chassis 4 Install the SCXI 1120 D into slot 4 of the SCXI chassis 1 Grounding screw 2 Module cover 1 2 ...

Page 5: ...ut channel has two user configurable gain stages The first stage gain provides gains of 1 10 50 and 100 The second stage gain provides gains of 1 2 5 10 and 20 Table 1 shows the jumper reference designators for gain selection associated with each channel Table 2 shows how to position each jumper to select the desired gain for each channel 1 Thumbscrews 2 Slot 4 3 Side plate Table 1 Gain Jumper Ref...

Page 6: ... for jumper reference designators and Figure 3 for the location of the jumpers 3 W4 W12 4 W5 W13 5 W6 W14 6 W7 W15 7 W8 W16 Table 2 Gain Jumper Positions Gain Setting Jumper Position First Stage 1 10 50 100 D C B A factory setting Second Stage 1 2 5 10 20 A B C D factory setting E Table 1 Gain Jumper Reference Designators Continued Input Channel Number First Stage Gain Jumper Second Stage Gain Jum...

Page 7: ...ber 4 Output Null Adjust Potentiometers 5 Second Stage Filter Jumpers 6 Rear Signal Connector 7 SCXIbus Connector 8 Input Null Adjust Potentiometers 9 First Stage Gain Jumpers 10 Second Stage Gain Jumpers 11 First Stage Filter Jumpers 12 Terminal Block Mounting Hole 13 Grounding Screw 3 6 7 1 2 1 4 5 8 9 10 11 12 12 Front Rear V25 V26 W27 W28 W29W30 W31V32V33 W34 W35 W36 V37 V38 V39 V40 W45 W43 W4...

Page 8: ...ion and the SCXI 1120 D module ships in the 4 5 kHz position Refer to Table 3 or 4 to find the correct jumper setting for the desired cutoff frequency Figure 3 shows the locations of the jumper blocks on the SCXI 1120 D modules Verify that both filter stages are set to the same filter setting to ensure that you achieve the required bandwidth Table 3 SCXI 1120 Filter Jumper Settings Input Channel N...

Page 9: ...ges used in your application 3 Set the channel filter for all channels on the module to 4 Hz for the SCXI 1120 module or 4 5 kHz for the SCXI 1120D module 4 Set the channel gain on all channels to the gain you want to test starting with the smallest gain available for the module Available gains are shown in Tables 7 and 8 5 Connect the calibrator to the analog input channel you are testing startin...

Page 10: ...CXI 1120 D Front Connector Pin Assignments Pin Number Column A Column B Column C 32 CH0 NP CH0 31 NP NP NP 30 CH1 NP CH1 29 NP NP NP 28 NC NP NC 27 NP NP NP 26 CH2 NP CH2 25 NP NP NP 24 CH3 NP CH3 23 NP NP NP 22 NC NP NC 21 NP NP NP 20 CH4 NP CH4 19 NP NP NP 18 CH5 NP CH5 17 NP NP NP 16 NC NP NC 15 NP NP NP 14 CH6 NP CH6 13 NP NP NP 12 CH7 NP CH7 11 NP NP NP 10 NC NP NC 9 NP NP NP 8 NC NP RSVD ...

Page 11: ...or that correspond to the positive and negative outputs for the specified channel For example the positive output for channel 0 is pin 3 which is labeled MCH0 The negative output for channel 0 is pin 4 which is labeled MCH0 7 NP NP NP 6 RSVD NP RSVD 5 NP NP NP 4 5V NP MTEMP 3 NP NP NP 2 CHSGND NP DTEMP 1 NP NP NP NP No pin NC No connect Table 5 SCXI 1120 D Front Connector Pin Assignments Continued...

Page 12: ...for the remaining analog input channels 11 Repeat steps 4 through 10 for the remaining gain settings specified in the appropriate table 12 Repeat steps 3 through 11 but set the channel filter to 10 kHz for the SCXI 1120 module or 22 5 kHz for the SCXI 1120D module You have completed verifying the operation of the module RSVD SERCLK DIG GND SLOT0SEL DAQD A SERDATIN OUTREF MCH7 NC NC NC NC NC NC NC ...

Page 13: ...hich is labeled CH0 The negative input for channel 0 is pin C32 which is labeled CH0 3 Connect the DMM to the output of the same channel to which the calibrator was connected in step 2 Refer to Figure 4 to determine the pins on the 50 pin rear connector that correspond to the positive and negative outputs for the specified channel For example the positive output for channel 0 is pin 3 which is lab...

Page 14: ...ng analog inputs You have completed adjusting the module Verifying Adjusted Values After you complete the adjustment procedure it is important to verify the accuracy of the adjusted values by repeating the procedure in the Verifying the Operation of the Module section Verifying the adjusted values ensures the module is operating within its specifications after adjustments Note If the SCXI 1120 D m...

Page 15: ...49248 2 300752 0 021 186 3 751095 3 688905 3 753353 3 686647 0 021 0 0 006922 0 006922 0 009180 0 009180 0 021 186 3 751095 3 688905 3 753353 3 686647 0 051 93 4 687000 4 613000 4 689236 4 610764 0 051 0 0 006784 0 006784 0 009020 0 009020 0 051 93 4 687000 4 613000 4 689236 4 610764 0 11 46 5 4 686925 4 613075 4 689186 4 610814 0 11 0 0 006709 0 006709 0 008970 0 008970 0 11 46 5 4 686925 4 61307...

Page 16: ...690046 4 609954 4 692331 4 607669 50 0 0 009831 0 009831 0 012115 0 012115 50 0 093 4 690046 4 609954 4 692331 4 607669 100 0 0465 4 689758 4 610242 4 692066 4 607934 100 0 0 009542 0 009542 0 011850 0 011850 100 0 0465 4 689758 4 610242 4 692066 4 607934 200 0 02325 4 689464 4 610536 4 691936 4 608064 200 0 0 009248 0 009248 0 011720 0 011720 200 0 02325 4 689464 4 610536 4 691936 4 608064 250 0 ...

Page 17: ... Lower Limit V Upper Limit V Lower Limit V 0 011 232 5 2 351764 2 298236 2 365234 2 284766 0 011 0 0 006230 0 006230 0 019700 0 019700 0 011 232 5 2 351764 2 298236 2 365234 2 284766 0 0251 186 4 698751 4 601249 4 733819 4 566181 0 0251 0 0 007683 0 007683 0 042750 0 042750 0 0251 186 4 698751 4 601249 4 733819 4 566181 0 051 93 4 697789 4 602211 4 768769 4 531231 0 051 0 0 006720 0 006720 0 07770...

Page 18: ... 0 0 007750 0 007750 0 077750 0 077750 5 0 93 4 698726 4 601274 4 768726 4 531274 10 0 465 4 700796 4 599204 4 841236 4 458764 10 0 0 009820 0 009820 0 150260 0 150260 10 0 465 4 700796 4 599204 4 841236 4 458764 25 0 18 5 070004 3 929996 4 870004 4 129996 25 0 0 530350 0 530350 0 330350 0 330350 25 0 18 5 070004 3 929996 4 870004 4 129996 50 0 086 4 360392 4 239608 4 825892 3 774108 50 0 0 022500...

Page 19: ... 176000 0 176000 1 713000 1 713000 500 0 006 3 273770 2 726230 4 810770 1 189230 1000 0 0029 3 416058 2 383942 4 895058 0 904942 1000 0 0 342000 0 342000 1 821000 1 821000 1000 0 0029 3 416058 2 383942 4 895058 0 904942 1Value available only when used with the SCXI 1327 high voltage terminal block Table 8 SCXI 1120D Specifications Continued 4 5KHz filter setting 22 5KHz filter setting Gain Test Po...

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