USER GUIDE
SCC-TC Series Thermocouple
Input Modules
The SCC-TC Series thermocouple input modules, SCC-TC01 and
SCC-TC02, accept input signals from B-, E-, J-, K-, N-, R-, S-, and T-type
thermocouples. The thermocouple inputs are filtered and passed into a
differential amplifier with a gain of 100. The output of the amplifier passes
through a dual-pole 2 Hz filter. Each module contains thermistor circuitry,
powered by a 2.5 V reference, to compensate for cold-junction effects.
Each module also can detect open thermocouple circuits.
Alternatively, you can connect voltage signals up to ±100 mV to the screw
terminals of the SCC-TC02 and use it as a low-bandwidth millivolt-input
module.
Conventions
The following conventions are used in this guide:
<> Angle brackets that contain numbers separated by an ellipsis represent
a range of values associated with a bit or signal name—for example,
ai<0..7>.
» The » symbol leads you through nested menu items and dialog box options
to a final action. The sequence File»Page Setup»Options directs you to
pull down the File menu, select the Page Setup item, and select Options
from the last dialog box.
This icon denotes a note, which alerts you to important information.
This icon denotes a caution, which advises you of precautions to take to
avoid injury, data loss, or a system crash. When this symbol is marked on
the product, refer to the Read Me First: Safety and Radio-Frequency
Interference document, shipped with the product, for precautions to take.
When symbol is marked on a product, it denotes a warning advising you to
take precautions to avoid electrical shock.
When symbol is marked on a product, it denotes a component that may be
hot. Touching this component may result in bodily injury.
bold Bold text denotes items that you must select in the software, such as menu
items and dialog box options. Bold text also denotes parameter names.
italic Italic text denotes variables, emphasis, a cross reference, or an introduction
to a key concept. This font also denotes text that is a placeholder for a word
or value that you must supply.
monospace Text in this font denotes text or characters that you should enter from the
keyboard, sections of code, programming examples, and syntax examples.
This font is also used for the proper names of disk drives, paths, directories,
programs, subprograms, subroutines, device names, functions, operations,
variables, filenames and extensions, and code excerpts.
SC-2345 SC-2345 refers to both the SC-2345 connector block and the SC-2345
configurable connector.
SCC SCC refers to any SCC series signal conditioning module.
What You Need to Get Started
To set up and use the SCC-TC0X, you need the following items:
❑ SC-2345 with one of the following:
–SCC-PWR01
– SCC-PWR02 and the PS01 power supply
– SCC-PWR03 (requires a 7 to 42 VDC power supply, not included)
❑ One or more SCC-TC0X modules
❑ SCC-TC Series Thermocouple Input Modules User Guide
❑ Read Me First: Safety and Radio-Frequency Interference
❑ SC-2345 User Manual, available online at ni.com
❑ SC-2345 Quick Reference Label
❑ 68-pin E Series DAQ device, documentation, and 68-pin cable
❑ 1/8 in. flathead screwdriver
SCC-TC Series Thermocouple Input Modules User Guide 2 ni.com
❑ Numbers 1 and 2 Phillips screwdrivers
❑ Wire insulation strippers
❑ NI-DAQ (current version) for Windows 2000/NT/XP
Note Software scaling of measurements is not supported on the Macintosh operating
system. Refer to the Converting Voltage Measurements to Temperature Measurements
section for more information about measurement scaling.
Unpacking the Module
SCC modules are shipped in antistatic envelopes to prevent electrostatic
damage (ESD) to the modules. ESD can damage several components on
these products.
Caution Never touch the exposed pins of connectors.
To avoid damage from ESD when you handle the module, take the
following precautions:
• Ground yourself by using a grounding strap or by touching a grounded
object.
• Touch the antistatic envelope to a metal part of the computer chassis
before removing the module from the envelope.
Remove the module from the envelope and inspect the module for loose
components or any sign of damage. Notify NI if the module appears
damaged in any way. Do not install a damaged module.
Store the module in the antistatic envelope when it is not in use.
Installing the Module
Caution Refer to the Read Me First: Safety and Radio-Frequency Interference document
before removing equipment covers or connecting/disconnecting any signal wires.
© National Instruments Corporation 3 SCC-TC Series Thermocouple Input Modules User Guide
A blue stripe on the label identifies the SCC-TC0X as an analog input
module. The label also displays the icon shown in Figure 1.
TC
Figure 1. SCC-TC0X Icon
You can plug the SCC-TC0X into any analog input socket on the SC-2345.
The socket you select determines which E Series DAQ device channels
receive the SCC-TC0X signals.
For single-stage input conditioning, plug the SCC-TC0X into any socket J
(X +1), where X is 0 to 7, and connect the input signals to the module as
described in the Connecting the Input Signals section.
If you use the SCC-TC0X in a dual-stage configuration, the SCC-TC0X
must be the first-stage module. Plug it into any socket J (X+9) and plug the
second-stage SCC into socket J (X+1), where X is 0 to 7. Connect the input
signals to SCC-TC0X as described in the Connecting the Input Signals
section. The SC-2345 connects the output signals of the first-stage SCC to
the inputs of the second-stage SCC. An example of dual-stage conditioning
in an SCC-TC0X followed by an SCC-LP01 lowpass filter module.
Sockets J9 to J16 also are available for digital input/output (DIO)
conditioning or control. Refer to the SC-2345 User Manual for more
information on configuring, connecting and installing SCC modules
Note SCC-TC0X dual-stage configuration is only available in NI-DAQ 7.1 or later.
Connecting the Input Signals
The SCC-TC01 has a two-prong uncompensated thermocouple
miniconnector that accepts any miniature or subminiature two-prong
male thermocouple connector. The SCC-TC02 has a three-position
screw-terminal connector that accepts 28 to 16 AWG thermocouple wires.
The screw-terminal connector provides a ground connection for shielded
thermocouples. Otherwise, the two modules function identically.
To use an SCC-TC01, plug the male thermocouple connector into the
module.
SCC-TC Series Thermocouple Input Modules User Guide 4 ni.com
The SCC-TC02 has a fixed screw-terminal receptacle and a removable
screw-terminal block, as shown in Figure 2.
1
3
2
1
2
1 SCC Screw-Terminal Receptacle 2 Removable Screw-Terminal Block
Figure 2. SCC-TC02 Two-Part Screw-Terminal System
After you install the SCC-TC02, attach the input signals to the screw
terminals of the module.
1. Remove power from the signal lines.
2. Strip 7 mm (0.28 in.) of insulation from the ends of the signal wires.
3. Insert the wires into the screw terminals.
4. Tighten the screws to 0.5 to 0.6 N ⋅ m (4.4 to 5.3 lb − in.) of torque.
The SCC-TC02 accepts up to three signals: TC+, TC–, and GND. TC+ is
the positive thermocouple lead and TC– is the negative thermocouple lead.
The GND terminal connects to AIGND on the E Series DAQ device.
The SCC-TC0X has a 10 MΩ bias resistor connected from the negative
thermocouple input to ground. This resistor allows the thermocouple to be
ground-referenced or floating without requiring external bias resistors
connected to ground.
1
For ANSI color-coded J-type thermocouples, the red wire is negative and the white wire is positive. Refer to the thermocouple
data sheet if possible. You can find information about other color-coding schemes in the NI KnowledgeBase at
support
.
© National Instruments Corporation 5 SCC-TC Series Thermocouple Input Modules User Guide
ni.com/
1
Thermocouple
Source
TC+
TC-
GND
(SCC-TC02
only)
SCC-TC0
Ref 5 V
10 MΩ
10 MΩ
Ref 5 V
4.75 kΩ
The amplified thermocouple signal and cold-junction sensor signal
are measured by E Series DAQ device channel X and channel X+8
respectively, where X is 0 to 7 depending on where you plug the
SCC-TC0X. Refer to Figure 3 for SCC-TC0X signal connections.
E Series
DAQ Device
ACH(X )
AISENSE
AIGND
1%
X
10 kΩ
10 kΩ
+
–
2-Pole Filter/
Buffer Stage
Offset
Calibrator
LM 4040
2.5 V
0.1%
0.1 µF
5 kΩ
0.1%
+
o
5 kΩ
-t
at 25
+
10 µF
o
C
16 V
–
0.1 µF
2.5 kΩ
Figure 3. SCC-TC0X Signal Connections
Cold-Junction Sensor Output and Accuracy
The cold-junction sensor voltage output varies from 1.91 to 0.58 V over a
0 to 55 °C temperature range.
Note NI-DAQ includes thermistor conversion utilities that implement the equations listed
below. Refer to your software documentation for more information on these utilities.
ACH(
X
+8)
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