There are a few different options: 1. What is a Thermocouple? 2. Thermocouple Types 3. Simcenter SCADAS Temperature Card 3.1 SCADAS T8 Card Hardware 3.2 SCADAS T8 Card Software Setup 4. Simcenter SCADAS Temperature CAN Bus Module 4.1 SCADAS TCK8 Module Hardware 4.2 SCADAS TCK8 CAN Interface and Power Options 4.3 SCADAS TCK8 Software Setup 5. Voltage Temperature Devices 5.1 EU Offset 5.2 Single versus Differential 5.3 Example Voltage Thermocouple Device 6. Numerical Temperature Display 6.1 Digital Readout versus Gauge 6.2 Celsius, Fahrenheit, Kelvin
1. What is a Thermocouple?
A thermocouple sensor (Figure 1) is used to measure temperature. It produces a voltage proportional to the temperature of the object with which the sensor is in contact.
Figure 1: Thermocouple sensor has two different conductive materials that form a junction to produce a voltage proportional to temperature.
A thermocouple has two different electrical conductors (for example copper and iron wires) which form an electrical junction.
In 1822, the German physicist Thomas Seebeck discovered that placing the two different wires so their ends form a loop, caused a voltage to develop in the circuit when the connection (or junction) were at different temperatures. This phenomenon is called the Seebeck effect and is the principal upon which thermocouples operate.
2. Thermocouple Types
The types of metals used in the construction of a thermocouple determines the temperature range that can be measured. Letters (B, E, J, K, N, R, S, and T) are used to designate the metal types used and corresponding temperature range as shown in Figure 2.
Figure 2: Thermocouple type versus continuous temperature range.
Due to its wide range, the K-Type Thermocouple is one of the most popular types. The K-Type wires are composed of:
Positive leg is composed of 90% nickel, 10% chromium
Negative leg is composed of 95% nickel, 2% aluminum, 2% manganese and 1% silicon.
Notice that N-Type has similar range to the K-Type. The N-Type is not as popular as the K-Type due to its higher expense. The N-Type has somewhat better accuracy from 572F to 932F (300C to 500C) than the K-type.
3. Simcenter SCADAS Temperature Card
The Simcenter SCADAS T8 card [Product codes: SCM-T8A, SCM-T8A-RT, etc.] measures eight thermocouples and supports B, E, J, K, N, R, S, and T Type thermocouples.
3.1 SCADAS T8 Card Hardware
The SCADAS T8 card occupies one slot of a Simcenter SCADAS frame as shown in Figure 3 below:
Figure 3: Simcenter SCADAS equipped with SCADAS T8 card and one thermocouple.
No external conditioning is required. Thermocouples plug directly into the openings on the card as shown in Figure 4:
Figure 4: Plugs on the SCADAS T8 Thermocouple Card accommodates thermocouple sensors directly.
The T8 is galvanically isolated up to 70 Volts. This helps prevent the metal thermocouple becoming bonded to test object and potentially causing high-voltage AC electric signals to accidentally come into the Simcenter SCADAS data acquisition system.
3.2 SCADAS T8 Card Software Setup
To use a SCADAS T8 card in Simcenter Testlab, go to “Tools -> Channel Setup Visibility” in the Channel Setup workbook.
In Source Field names, find “Thermocouple” and add it to the “Selected Fields” column from the “Source Fields names” column as shown in Figure 5:
Figure 5: Under “Tools -> Channel Setup Visibility” find “Thermocouple” and add it to the Selected Fields column from the “Source field names” column.
In the Channel Setup, turn on the T8 channel and choose the Thermocouple Type as shown in Figure 6:
Figure 6: Turn on the channel and choose the Thermocouple Type.
The thermocouple Type can be set separately on each channel via the Simcenter Testlab software. For example, a K -Type and T-Type thermocouple can be measured on two consecutive channels. This allows a larger temperature range to be measured simultaneously.
The SCADAS T8 card occupies a full slot of the SCADAS frontend hardware. Instead of using a slot, a SCADAS TCK8 module can be used via the CAN bus.
SCADAS TCK8 modules are described in the next section.
4. Simcenter SCADAS Temperature CAN Bus Module
The Simcenter SCADAS Thermocouple CAN bus K-Type (TCK8) solution are eight channel temperature modules. The modules are connected to the SCADAS frontend via a Controller Area Bus (CAN bus). Product codes SC-TCK8A and SC-TCK8B.
4.1 SCADAS TCK8 Module Hardware
Each SCADAS TCK8 module measures eight thermocouples. The modules are usually purchased as a pair called TCK8-A and TCK8-B. The A module is the main module which connects to the SCADAS. Additional secondary B modules can then be connected to the A.
A SCADAS TCK8-A module can power the SCADAS TCK8-B module via daisychain cable connection. The connectors also require a terminator. The TCK8 modules are shown in Figure 7:
Figure 7: A TCK8 pair (A and B) front view (left) and rear view (right). A and B markings are found on the bottom of the units.
The SCADAS TCK8 have:
Ingress protection (IP) rating of 67 for dust and water intrusion.
Support a single thermocouple type. The default is K-type.
The SCADAS TCK8 module connects to a SCADAS frontend via a CAN bus input. An example with a SCADAS CN4 CAN bus card is shown in Figure 8:
Figure 8: SCADAS TCK8 thermocouple module plugged into to SCADAS CN4 CAN bus card.
In this example, a single SCADAS TCK8 temperature module is plugged into the SCADAS hardware.
4.2 SCADAS TCK8 CAN Interface and Power Options
There are two options for connecting a CAN bus device to a SCADAS:
Built-in CAN bus: Many SCADAS controller cards have a CAN bus interface.
SCADAS CN4 Card: The SCADAS CN4 has four CAN inputs. It occupies one slot in the SCADAS frame.
An example of a SCADAS system with four TCK8 modules (32 thermocouples) is shown in Figure 9.
Figure 9: SCADAS system with four TCK8 modules supporting up to 32 thermocouples.
A single CAN interface on the SCADAS CN4 card can power and measure 16 thermocouple total. The CAN is connected to a SCADAS TCK8-A module. The SCADAS TCK-B module is daisychained with the SCADAS TCK-A module.
SCADAS TCK8 modules can be powered two different ways depending on the SCADAS CAN input:
SCADAS CN4 Card: Up to four SCADAS TCK8 modules can be used and powered when using a SCADAS CN4 card. Four SCADAS TCK8 modules support 32 channels of thermocouples total.
SCADAS Built-in Single CAN bus: No power is provided by the built-in CAN interface on a SCADAS controller card. External power is required.
For the built-in single CAN bus, there is a special order cable that splits the power to banana plugs. Using external power, up to to ten SCADAS TCK8 modules can be used for 80 thermocouples total.
The SCADAS CN4 card has two physical CAN ports. Cables are provided that splits each port into two. This makes four CAN connections possible with the SCADAS CN4 card. The cable and card are shown in Figure 10:
Figure 10: SCADAS CN4 Can bus card and splitter cable.
Using the splitter cable with the TCK8 modules allows other CAN measurements to be acquired. For example, in addition to temperature measurements with a TCK8, a vehicle bus could also be acquired.
4.3 SCADAS TCK8 Software Setup
After starting Simcenter Testlab Signature, go to the “Channel Setup” workbook. In the upper right, select “CAN Settings” from the upper right as shown in Figure 11:
Figure 11: Simcenter Testlab CAN bus interface in the Channel Setup worksheet.
Follow these steps to setup a TCK8 in Simcenter Testlab (Figure 11):
In the upper right of Channel Setup, select “CAN Settings”.
Under “DB Path”, load the TCK8 DBC file (included in Testlab): It is located in this directory: C:\Program Files (x86)\Simcenter\Testlab 2206\central\Application Resources\CAN. The file is called “TCK-8AB.dbc”.
Set the “CAN ACK” mode to “Passive”.
Press “Show All” button on left side of screen.
Check off the channels to be measured.
The TCK8 modules with a SCADAS CN4 card cannot be used with a SCADAS Mobile 01 frame. There must be at least one dynamic input card in the frame.
There are several devices (Fluke meters, etc.) that output a voltage that is proportional to temperature. After hooking the device into a data channel of a SCADAS, the “Input Mode” should be set to “Voltage DC” and the “Measured Quantity” to “Temperature” as shown in Figure 12.
Figure 12: Simcenter Testlab channel setup to support external voltage-based temperature device.
Some other considerations:
5.1 Offset EU
Because temperature is actual stored in terms of “absolute temperature” (Kelvin is absolute temperature of Celsius), the offset needs to be entered in the channel setup information. This is needed to support an external voltage based temperature device.
Choose “Tools -> Channel Setup Visibility” and add “Offset EU” to the Channel Setup. EU is short for Engineering Unit. Then change the value from 0 to 273.15 for Celsius as shown in Figure 13.
Figure 13: An Engineering Unit (EU) offset must be set on temperature channels when using a voltage output temperature device.
If working in Fahrenheit, the offset will be 459.67. The English unit needs to be the active Testlab Unit system. More about changing the unit system here: Simcenter Testlab Units.
5.2 Single Ended versus Differential
Devices that output a voltage can carry the voltage signal on one wire (single-ended) or two wires (differential). Simcenter SCADAS cards like the VB8 can accommodate either single-ended or differential signals.
Simcenter Testlab must be setup to match the voltage device a shown in Figure 14.
Figure 14: In the coupling field, set the mode to either “Single-Ended” or “Differential”.
Be sure that the coupling setting matches how the signals come from the temperature device. The lights on the SCADAS frontend reflect whether single-ended (green light) is selected or differential (blue) is selected.
The Numerical display in Simcenter Testlab is useful for displaying temperature. The display shows a single value as shown in Figure 16:
Figure 16: Numerical display (center) for temperature.
Choose either the display icon or the “Create a Picture…” button and select “Numerical”. Drag the temperature data from the “Online Data” folder of the Data explorer into the display.
6.1 Digital Readout versus Gauge
By default, the Numerical Display shows a large digital readout of numbers. This number display can be turned into a gauge by right clicking on the display and choosing “Gauge” as shown in Figure 17.
Figure 17: Right click on the numerical display to switch between Gauge and Numerical mode.
Both the Numerical and Gauge modes of the display can be programmed to change colors when certain thresholds are met. Right click on the display and choose “Color Scale” as shown in Figure 18:
Figure 18: Use the “Color Scale” to have the Numerical display change colors above and below certain thresholds.
For example, the “Color Scale…” menu can be used to set the display red when the temperature exceeds the maximum warning threshold.
6.2 Celsius, Fahrenheit, Kelvin
To switch the temperature units being shown in the displays, go to the Channel Setup worksheet and find the “Actual Sensitivity Field” as shown in Figure 19.
Figure 19: Right click in display to convert between different temperature measurement units.
The Numerical display changes to the unit selected in the Actual Sensitivity field.
If displaying temperature data in Front/Back field, units can be switched by right clicking on the Y-axis as shown in Figure 20:
Figure 20: Right click in display to convert between different temperature measurement units.
How the channel name appears in the Numerical display can also be controlled as explained in the next section.
6.3 Channel Naming Tip
When creating point names, especially with CAN bus channels, the characters “::” are often used. In the Numerical display, there is an option to allow only the characters that appear after the “::” to be shown (Figure 21).
Figure 21: Top – Channel setup with name “TCK8A_11::COOLANT TEMPERATURE”. Bottom – Using the “Options” menu of the Numerical display, only “COOLANT TEMPERATURE” can be shown in the display.
This is done by right clicking on the numerical display and choosing “Options”. The check on the “Display ::name only” checkbox.