National Instruments TC-2095 Manual

©2002 National Instruments Corp. All rights reserved.
National Instruments™, NI™, ni.com™, and SCXI™ are trademarks of National Instruments Corporation. Product and
company names mentioned herein are trademarks or trade names of their respective companies. For patents covering
National Instruments products, refer to the appropriate location: Help»Patents in your software, the patents.txt file
on your CD, or ni.com/patents.
July 2002
370565A-01
TC-2095 RACK-MOUNT TERMINAL BLOCK
CALIBRATION PROCEDURE
Introduction
This document contains step-by-step instructions for verifying the
performance of the temperature sensor on the National Instruments
TC-2095 rack-mount terminal block. This temperature sensor is for
cold-junction compensation of thermocouples on the terminal block.
What Is Calibration?
Calibration consists of verifying the measurement accuracy of a device
and correcting for any measurement error. For TC-2095 terminal blocks,
calibration is simply verifying the measurement accuracy of the
components on the terminal block. Because these components are not
user adjustable, calibration consists of verification only, without correcting
for any error. Verification is measuring the performance of a device and
comparing the results to the factory specifications of the device.
Why Should You Verify?
The accuracy of electronic components drifts with time and temperature,
which can affect measurement accuracy as the device ages. Verification
ensures the TC-2095 terminal block still meets NI standards. If the results
of the procedure indicate that the temperature sensor on the terminal block
is out of specification, return the device to NI for repair or replacement.
How Often Should You Verify?
The measurement accuracy requirements of your application determine
how often you should verify the performance of the TC-2095.
NI recommends you verify the terminal block at least once every year.
You can shorten this interval to six months or 90 days based on the
demands of your application.
ni.com

TC-2095 Terminal Block Calibration Procedure 2 ni.com
Equipment and Other Test Requirements
This section describes the equipment, software, documentation, and test
conditions required for verifying the performance of the TC-2095.
Test Equipment
Verification requires a high-precision voltage source with at least 50 ppm
accuracy, a multiranging 5 1/2 digit digital multimeter (DMM) with
15 ppm accuracy, and a thermometer that is accurate to within 0.1 °C.
NI recommends you use the following instruments for verifying the
performance of the TC-2095:
• Calibrator—Fluke 5700A
• DMM—NI 4060 or Agilent 34401A
Note You also need three test connector adapters that fit the 96-pin connector pins.
Use a Pomona 3560 banana jack to test adapter connector (0.040 in. diameter pins) or
an equivalent connector.
If these instruments are not available, use the accuracy requirements listed
above to select a substitute calibration standard.
Software and Documentation
You can find all the necessary information to verify the performance
of the TC-2095 in this verification procedure. No other software or
documentation is required. If you would like more information on the
TC-2095, refer to the BNC/TC-205 Rack-Mount Adapter Installation
Guide, which you can download from the NI Web site at
ni.com/manuals.
Test Conditions
Follow these guidelines to optimize the connections and the environment
during verification:
• Keep connections to the TC-2095 terminal block short. Long cables
and wires act as antennae, picking up extra noise that can affect
measurements.
• Use shielded copper wire for all cable connections to the terminal
block. Use twisted-pair wire to eliminate noise and thermal offsets.
• Keep relative humidity below 80%.
• Maintain a temperature between 15 and 35 °C.

©National Instruments Corporation 3 TC-2095 Terminal Block Calibration Procedure
Verification Procedure
This section contains step-by-step instructions for verifying the
performance of the temperature sensor on the TC-2095 terminal block.
Verifying Temperature Sensor Performance
Complete the following steps, while referring to Figures 1 and 2, to verify
the performance of the temperature sensor on the terminal block.
1. Connect a +5 VDC power source to the terminal block.
a. Hold the terminal block horizontally upright and view it from the
rear. The terminals on the 96-pin DIN connector are designated
as follows:
–Column A is on the bottom, Column B is in the middle,
and Column C is on the top.
–Row 1 is on the right and Row 32 is on the left.
Figure 1 illustrates the connector pin assignments. Individual pins
are identified by their column and row. For example, A3 denotes
the terminal located in Column A and Row 3. This corresponds to
the labeling of the pins on the front connector of a mating SCXI
module.
Figure 1. TC-2095 Connector Pin Assignments
1
O
N
2345678
1
O
N
2345678
1
O
N
2345678
1
O
N
234 5678 1
O
N
234 5678
1
O
N
234 5678
1
O
N
234 5678
1
O
N
2345678
C1 B1 A1

TC-2095 Terminal Block Calibration Procedure 4 ni.com
b. Connect a test connector adapter to terminal A1 on the 96-pin
female DIN connector on the rear of the terminal block. Attach
the other end of this wire to the positive terminal of the +5 VDC
power supply.
c. Connect a test connector adapter to terminal A2 on the 96-pin
female DIN connector on the rear of the terminal block. Attach
the other end of this wire to the negative terminal of the +5 VDC
power supply.
2. Connect a calibrated DMM to the temperature-sensor output of the
terminal block.
a. Refer to Figure 2 to locate jumper W1 and verify that MTEMP
is jumpered on the terminal block.
Figure 2. TC-2095 Terminal Block Parts Locator Diagram
1 Cover
2Screws
3 CJC Sensor
4 DTEMP/MTEMP Jumper
5 W2 Jumper
5
4
1
2
3

©National Instruments Corporation 5 TC-2095 Terminal Block Calibration Procedure
b. Connect a test connector adapter to terminal A3 on the 96-pin
female DIN connector on the rear of the terminal block. Attach
the other end of this wire to the positive input terminal of the
calibrated DMM.
c. Connect the negative input terminal of the calibrated DMM to the
negative terminal of the +5 VDC power supply.
3. Place the terminal block in a temperature-controlled environment
where the temperature is between 15 and 35 °C.
4. When the terminal block temperature reaches equilibrium with its
surroundings, measure the temperature sensor output Vmeas using a
calibrated DMM.
5. Measure the actual temperature Tact in the temperature-controlled
environment using a thermometer calibrated to within 0.1 °C accuracy.
Position the thermometer as near as possible to the CJC sensor.
6. Convert Vmeas (in volts) to measured temperature Tmeas by performing
the following calculations:
a. Calculate
b. Calculate
c. Calculate
where Tmeas is in degrees Celsius
a= 1.295361 ×10–3
b= 2.343159 ×10–4
c= 1.018703 ×10–7
x2.5 Vmeas
–
5,000
---------------------------=
yVmeas
x
-------------



ln=
Tmeas
1
aybcy
2
+()+
---------------------------------- 273.15–=

TC-2095 Terminal Block Calibration Procedure 6 ni.com
7. Compare Tact to Tmeas.
•If (Tmeas −0.5 °C) ≤Tact ≤(Tmeas +0.5 °C), the performance of the
terminal block temperature-sensor has been verified.
•If Tact <(Tmeas −0.5 °C), the terminal block temperature sensor is
nonfunctional. Return the terminal block to NI for repair or
replacement.
•If Tact >(Tmeas +0.5 °C), the terminal block temperature sensor is
nonfunctional. Return jumper W1 to its original position. Return
the terminal block to NI for repair or replacement.
You have completed verifying the performance of the temperature sensor
on the TC-2095 terminal block.