MCC 134
Thermocouple DAQ HAT for Raspberry Pi®
Features• Four isolated thermocoupleinputs• 24-bit A/D converter• 1 second update interval,minimum• Thermocouple types J, K, R, S,T, N, E, and B supported• Cold junction compensation• Linearization• Screw terminal connections
The MCC 134 is a 24-bit, 4-channel HAT add-on board for thermocouple measurements.
The board is shown here connected to a Raspberry Pi (not included).

• Stack up to eight MCC HATs
onto a single Raspberry Pi

SoftwareOverview
The MCC 134 is a thermocouple measurement HAT (Hardware Attached on Top)
designed for use with Raspberry Pi, the most popular single-board computer on
the market today.
A HAT is an add-on board with a 40W GPIO (general purpose input/output) connector that conforms to the Raspberry Pi HAT specification.
The MCC 134 HAT provides four isolated thermocouple inputs. Up to eight MCC
DAQ HATs can be stacked onto one Raspberry Pi.

• MCC DAQ HAT Library;
available on GitHub

Supported Operating Systems• Linux®

Programming API• C, C++, Python

Raspberry Pi Interface

Thermocouple Input

PowerThe MCC 134 header plugs into the 40-pin
general purpose I/O (GPIO) connector on auser-supplied Raspberry Pi. The MCC 134
was tested for use with all Raspberry Pimodels with the 40-pin GPIO connector.

Users can connect up to four differential
thermocouples (TC) to the MCC 134 input
channels. TC types are software-selectableper channel. TC values can be updated
every 1 second, minimum.

The MCC 134 is powered with 3.3 V and5 V provided by the Raspberry Pi throughthe GPIO header connector.

Thermocouple inputs are electrically isolated from the Raspberry Pi to minimize
noise and provide protection from harshelectrical environments.

The open-source MCC DAQ HAT Libraryof commands in C/C++ and Python
allows users to develop applications onthe Raspberry Pi using Linux.

HAT Configuration
HAT configuration parameters are stored
in an on-board EEPROM that allows theRaspberry Pi to automatically set up theGPIO pins when the HAT is connected.

Stackable HATs
Up to eight MCC DAQ HAT boards can bestacked onto a single Raspberry Pi. Users
can mix and match MCC HAT models
in the stack.

Cold-Junction Compensation
The MCC 134 has three high-resolution
cold-junction compensation (CJC)
sensors.

Open-Thermocouple
Detection
The MCC 134 is equipped with openthermocouple detection (OTD) for all
TC input channels so users can monitor
the board for broken or disconnected
thermocouples.

Measurement Computing(508) 946-5100

1

MCC DAQ HAT Library

The library is available to download fromGitHub. Comprehensive API and hardware documentation is available.
The MCC DAQ HAT Library supports
operation with multiple MCC DAQ HATs
running concurrently.
Console-based and user interface (UI)
example programs are available.

info@mccdaq.com

mccdaq.com

MCC 134
Block Diagram
Isolation Barrier

Screw Terminals+3.3 V

Input
Filters,ESD,andOTD

Isolated
Power
Supply24-bit ADC+5 VDigital
Isolator

Board
Address
Matching

SPI

HAT
EEPROM

Raspberry Pi
HeaderI2C

CJC Sensors

Best Practices for Accurate Thermocouple Measurements
The MCC 134 should achieve results within the maximum thermocouple accuracy specifications when operating within the documented environmental conditions. Operating in conditions with excessive temperature transients or airflow may affect results.
In most cases, the MCC 134 will achieve the typical specifications. To achieve the most accurate thermocouple readings, MCC
recommends the following practices:••

Reduce the load on the Raspberry Pi processor. Running a
program that fully loads all 4 cores on the Raspberry Pi
processor can raise the temperature of the processor above
70 °C. Running a program that only loads 1 core will operate approximately 20 °C cooler.
Minimize environmental temperature variations. Place theMCC 134 away from heat or cooling sources that cycleon and off. Sudden environmental changes may lead toincreased errors.

•Provide a steady airflow, such as from a fan. A steady airflow
can dissipate heat and reduce errors.

•When configuring multiple MCC DAQ Hats in a stack, position the MCC 134 farthest from the Raspberry Pi board. Since
the Raspberry Pi is a significant heat source, placing theMCC 134 farthest from the Pi will increase accuracy.

For additional information, refer to the Measuring Thermocouples
with the Raspberry Pi and the MCC 134 Tech Tip.

Stackable
Connect up to eight MCC DAQ HATs onto a singleRaspberry Pi. Configure onboard jumpers to identify eachboard in the stack.

Measurement Computing(508) 946-5100

2

info@mccdaq.com

mccdaq.com

MCC 134
Example Programs
MCC DAQ HAT Examples

Web Server (Python)

The web server example lets users configure acquisition optionsand view acquired data from a browser window. This example
is written for Python (source included).

The MCC DAQ HAT Library includes example programs
developed in C/C++ and Python that users can run to become
familiar with the DAQ HAT library and boards; source code isincluded.

Console-Based (C/C++)
The compiled console example reads and displays the value ofeach thermocouple channel in a software timed loop.

Continuously read and display the value of each thermocouple input

Configure options and view strip chart data from your browser

User Interface

IFTTT Applet (Python)

Example programs featuring a user interface are provided indifferent formats. Examples of each are shown here.

IFTTT (If This Then That) is a free web-based service that interacts with apps and hardware to automate various functions. AnIFTTT account is required.

DataLogger (C/C++)The DAQ HAT Library includes two IFTTT example programs
written for Python (source included):

The datalogger example acquires data from the MCC 134, displays the data on a strip chart, and logs the data to a CSV file.
This example can be run from the terminal.

•The logging example reads one channel at regular intervals
and writes the data to a Google Sheets spreadsheet. Users
can remotely monitor the spreadsheet from Google Drive(shown below).

•The alarm example monitors one channel and sends anemail if the channel value meets specified criteria.

Configure options, plot data on a strip chart, and log data to a file

Remotely monitor acquired data from your browser

Measurement Computing(508) 946-5100

3

info@mccdaq.com

mccdaq.com

MCC 134
Specifications
All specifications are subject to change without notice.
Typical for 25 °C unless otherwise specified.

Thermocouple input

A/D converters: Delta-Sigma
ADC resolution: 24 bits
Number of channels: 4Input isolation
Between input and Raspberry Pi ground: 500 Vpk withstand max
Differential input voltage range: ±78.125 mV
Common mode voltage range
Between any CHx+ or – input and any other input: 0.8 V max
Absolute maximum input voltage
Between any two TCx inputs: ±25 V (power on), ±25 V (power off)
Differential input impedance: 40 MΩ
Input current: 83 nA
Common mode rejection (fIN = 50 Hz or 60 Hz): 100 dB
Update interval: 1 second minOpen thermocouple detect response time: 2 seconds
Recommended Warm-up time: 15 minutes min
Calibration method: Factory

Compatible thermocouples
J: –210 °C to 1200 °C
K: –270 °C to 1372 °C
R: –50 °C to 1768 °C
S: –50 °C to 1768 °C

T: –270 °C to 400 °C
N: –270 °C to 1300 °C
E: –270 °C to 1000 °C
B: 50 °C to 1820 °CAccuracy
Thermocouple measurement accuracy

Thermocouple accuracy specifications, including typical CJC measurement error.
All specifications are (±).
Note 1: Thermocouple measurement accuracy specifications include polynomial
linearization, cold-junction compensation error, and system noise. Accuracies shown do not include inherent thermocouple error or large temperature
gradients across the board. Contact your thermocouple supplier for details on
the inherent thermocouple accuracy error. The accuracy specifications assume
the device has been warmed up for the recommended 15 minutes.
Note 2: To avoid excessive cold-junction compensation errors, operate the device
in a stable temperature environment and away from heat sources that could
cause temperature gradients across the board. Refer to the documentation forways to decrease this error.
Note 3: When thermocouples are attached to conductive surfaces, the voltage
differential between multiple thermocouples must remain within ±0.8 V. For
best results MCC recommends using electrically insulated thermocouples whenpossible.

Measurement Computing(508) 946-5100

4

info@mccdaq.com

mccdaq.com

MCC 134
Specifications and Ordering

MemoryNon-volatile memory: 4 KB (ID and calibration storage, no user-modifiablememory)

Power

Supply current
5 V supply: 16 mA typ, 24 mA max
3.3 V supply: 1 mA typ, 5 mA max

Interface

Raspberry Pi GPIO pins used:
GPIO 8, GPIO 9, GPIO 10, GPIO 11 (SPI interface)
ID_SD, ID_SC (ID EEPROM)
GPIO 12, GPIO 13, GPIO 26, (Board address)
Data interface type: SPI slave device, CE0 chip selectSPI mode: 1SPI clock rate: 10 MHz, max

Environment

Operating temperature: 0 °C to 55 °C
Storage temperature: –40 ˚C to 85 °C max
Relative humidity: 0% to 90% non-condensing

Mechanical

Dimensions (L × W × H): 65 × 56.5 × 12 mm (2.56 × 2.22 × 0.47 in.) max

Order Information

Accessories

HardwarePart No.

Description

745690-E001

E-type thermocouples wire, fiberglass(0 °C to 482 °C, 32 °F to 900 °F), 1 m745690-E002

E-type thermocouples wire, fiberglass(0 °C to 482 °C, 32 °F to 900 °F), 2 m

745690-J001

J-type thermocouples wire, fiberglass(0 °C to 482 °C, 32 °F to 900 °F), 1 m

745690-J002

J-type thermocouples wire, fiberglass(0 °C to 482 °C, 32 °F to 900 °F), 2 m

Part No.

Description

MCC 134

4-channel thermocouple measurement DAQ HAT.
Raspberry Pi model with the 40-pin GPIO connector
required.

SoftwarePart No.

Description

745690-K001

MCC HAT
Library

Open-source library for developing applications in C, C++,and Python on Linux for MCC DAQ HAT hardware.
Available for download on GitHub at https://github.com/
mccdaq/daqhats.

K-type thermocouples wire, fiberglass(0 °C to 482 °C , 32 °F to 900 °F), 1 m

745690-K002

K-type thermocouples wire, fiberglass(0 °C to 482 °C, 32 °F to 900 °F), 2 m

745690-T001

T-type thermocouples wire, fiberglass(0 °C to 260 °C, 32 °F to 500 °F), 1 m

745690-T002

T-type thermocouples wire, fiberglass(0 °C to 260 °C, 32 °F to 500 °F), 2 m

Measurement Computing
DS-MCC-134(508) 946-5100

5

info@mccdaq.com

mccdaq.com
May 2020. Rev 3© Measurement Computing Corporation