MAX31855 Evaluation Kit
Evaluates: MAX31855
General Description
The MAX31855 evaluation kit (EV kit) provides the
hardware and software (GUI) necessary to evaluate the
MAX31855 cold-junction compensated thermocouple-to-
digital converter.
The MAX31855 EV kit comes with a MAX31855KASA+
soldered to the PCB. This is the K-type thermocouple ver-
sion of the MAX31855. Other thermocouple types can be
evaluated by procuring the desired thermocouple, ther-
mocouple socket, and corresponding MAX31855. Contact
the factory for free samples of the MAX31855 to match
your desired thermocouple type. See the
Evaluating Other
Thermocouple Types
section for part numbers and addi-
tional information regarding other thermocouple types.
Features
S
Includes Everything Needed to Evaluate a K-Type
Thermocouple
S
EV Kit Hardware is USB Powered (USB Cable Included)
S
Windows XP
®
, Windows Vista
®
, and Windows
®
7
Operating Systems-Compatible Software
S
USB HID Interface
S
Graphical User Interface (GUI) Consists of a
Single .EXE File
S
Second Channel Allows Easy Evaluation of Other
Thermocouple Types
S
RoHS Compliant
EV Kit Contents
S
Assembled Circuit Board Including MAX31855KASA+
S
Mini-USB Cable
S
K-Type Thermocouple
Ordering Information
appears at end of data sheet.
FILE
MAX31855 EV Kit Files
DESCRIPTION
Application program
MAX31855EVkit.EXE
Note:
The .EXE file is downloaded as a .ZIP file.
MAX31855 EV Kit Board
Windows XP, Windows Vista, and Windows are registered trademarks of Microsoft Corp.
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-6072; Rev 0; 10/11
MAX31855 Evaluation Kit
Evaluates: MAX31855
Quick Start
Note:
In the following sections, software-related items
are identified by bolding. Text in
bold
refers to items
directly from the EV kit software. Text in
bold and under-
lined
refers to items from the Windows operating system.
• PC with Windows XP, Windows Vista, or Windows 7
OS with a spare USB port
• K-type thermocouple (included)
• Mini-USB cable (included)
• EV kit hardware
Follow the steps below to get started measuring tem-
perature using the MAX31855 interfaced to a K-type
thermocouple.
8) Once the device driver installation is complete (from
an earlier step), double-click the .EXE file to run the
GUI. A message box stating
The publisher could
not be verified. Are you sure you want to run this
software?
may appear. If so, click
Run.
9) When the GUI appears, the
EV Kit Status
group box
should indicate that the EV kit hardware is ready. Also,
the COM LED (D2) should turn green.
10)Click the
Single Read
button to read the temperature.
A valid temperature should be displayed along with all
four
Alarm Status
indicators remaining green. At this
point, the EV kit and setup is fully functional and ready
to begin evaluating the MAX31855. If any issues arise,
see the
Troubleshooting
section.
Required Equipment
Procedure
Detailed Description of Software
Figure 1
shows a screenshot of the MAX31855 GUI.
On the right-hand side of the GUI is a section titled
EV
Kit Status.
It is used to indicate the status of the com-
munication between the GUI and the EV kit hardware. If
everything is working properly, a message indicates that
the hardware is present and/or ready. Otherwise,
EV Kit
not found.
is displayed.
The drop-down box in this section is used to select the
thermocouple type installed on the EV kit hardware. See
Table 1
for the list of possible settings. Out-of-the-box,
the hardware contains a K-type version of the MAX31855
along with a K-type thermocouple and socket. Therefore,
the drop-down box defaults to the K-type setting. The
thermocouple type selection is used by the GUI to calcu-
late the linearized temperature values.
1) Connect the included K-type thermocouple to J2
(thermocouple socket) of the EV kit hardware. One
terminal of the thermocouple is wider than the other,
ensuring proper polarity.
2) Ensure that jumper/shunt J4 is installed and is select-
ing Channel 1.
3) Set the EV kit hardware on a nonconductive surface
that ensures nothing on the PCB gets shorted togeth-
er.
4) Prior to starting the GUI, connect the EV kit hardware
to a PC using the supplied mini-USB cable, or equiva-
lent. The COM LED (D2) should flash between red
and orange.
5) Windows should automatically begin installing the
necessary device driver. The USB interface of the
EV kit hardware is configured as an HID device and
therefore does not require a unique/custom device
driver. Once the driver installation is complete, a
Windows message appears near the
System Icon
menu indicating that the hardware is ready to use. Do
not attempt to run the GUI prior to this message. If you
do, you must close the application and restart it once
the driver installation is complete. On some versions
of Windows, Administrator privileges may be required
to install the USB device.
6) Go to
www.maximintegrated.com/MAX31855EVKIT
to download the latest version of the EV kit software,
titled MAX31855EVkit.ZIP. Save the EV kit software to a
temporary folder.
7) Open the .ZIP file and extract the .EXE file to your
desired location. The .EXE file is the actual EV kit GUI
and not an install program. You can store the .EXE
wherever you like and then uninstall it later by simply
deleting the .EXE file.
Maxim Integrated
EV Kit Status Section
Thermocouple Type Section
Table 1. Thermocouple Types and
Sensitivities
TYPE
K*
J
N
S
T
E
R
*Default
setting.
SENSITIVITY (µV/NC)
41.276
57.953
36.256
9.587
52.18
76.373
10.506
2
MAX31855 Evaluation Kit
Evaluates: MAX31855
Figure 1. MAX31855 EV Kit GUI
Interfacing to the MAX31855 is simple. The interface
is read-only and consists of one 32-bit shift register.
When the
Single Read
button is pressed, all 32 bits
are read, parsed, and then displayed. The raw data
read from the device is shown in both binary and hexa-
decimal format in the edit boxes labeled
Raw B[31:0].
Furthermore, the four fault bits are analyzed and then
their states are indicated in the
Alarm Status
sec-
tion. The
Raw Thermocouple Temperature
and
Cold
Junction Temperature
edit boxes are calculated. And
finally, the
Linearized Thermocouple Temperature
edit
Read from the MAX31855 Section
box is calculated using the sensitivity value and NIST
coefficients to compensate for thermocouple nonlineari-
ties. Refer to the MAX31855 IC data sheet for additional
information.
This section allows the user to enter a desired number
of samples (temperature readings) as well as the delay
between the samples (in milliseconds) in order to auto-
mate temperature readings. It is also possible to write the
results to a file by clicking the
Log to file
checkbox and
providing a folder and filename for the comma separated
value (.CSV) file to be stored.
Multiple Reads Section
Maxim Integrated
3
MAX31855 Evaluation Kit
Evaluates: MAX31855
Detailed Description of Hardware
The MAX31855 EV kit hardware provides everything
needed to evaluate a K-type thermocouple. In addition to
a thermocouple and MAX31855, the hardware includes
a USB interface that is used to communicate with the
PC-based software. An added feature is that the hard-
ware is USB powered, meaning that
no power supplies
are needed.
The EV kit hardware features two thermocouple channels.
Channel 1 comes preconfigured with a MAX31855KASA+,
K-type thermocouple, and thermocouple socket. A sec-
ond channel is provided to make it easy to evaluate other
thermocouple types. Channel 2 is almost fully populated,
missing only the desired MAX31855 version, correspond-
ing thermocouple, and thermocouple socket. A jumper
(J4) is used to select the desired channel. The following
section describes how to modify the hardware in order to
evaluate other thermocouple types.
To use Channel 2, see
Table 2
for the part numbers of the
three items required for the desired thermocouple type.
Evaluating Other Thermocouple Types
Once the three items have been procured, carefully
solder the Maxim device to the footprint labeled U3 and
the thermocouple socket to the footprint labeled J3.
Obviously, make sure this is done with the board unpow-
ered. Move the jumper, J4, to the Channel 2 position.
Finally, connect the thermocouple to the socket.
Reconnect the USB cable to the PC and then run the
GUI. Select the correct
Thermocouple Type
from the
drop-down box. The hardware and software are now
ready to begin evaluation.
The jumper, J4, is used to select the desired channel.
See
Table 3
for additional details.
Thermocouple Channels
Description of Channel Selection Jumper
Table 2. Items Required to Evaluate Other Thermocouple Types
TYPE
K
J
N
S
T
E
R
MAXIM PART
MAX31855KASA+
MAX31855JASA+
MAX31855NASA+
MAX31855SASA+
MAX31855TASA+
MAX31855EASA+
MAX31855RASA+
THERMOCOUPLE*
5SRTC-GG-K-24-36
5SRTC-GG-J-24-36
NMQIN-010E-6 (unverified)
—
5SRTC-GG-T-24-36
5SRTC-GG-E-24-36
—
SOCKET*
PCC-SMP-K-5
PCC-SMP-J-5
PCC-SMP-N-5
—
PCC-SMP-T-5
PCC-SMP-E-5
—
*Thermocouple
and socket part numbers are Omega part numbers (www.omega.com). Contact Omega for RoHS part numbers.
Table 3. MAX31855 EV Kit Jumper Description (J4)
JUMPER
JUMPER POSITION
1-2*
J4
2-3
*Default
position.
DESCRIPTION
Selects Channel 1.
The SO (serial out) pin of the Channel 1 MAX31855 is connected to
the USB PC Interface
Selects Channel 2.
The SO (serial out) pin of the Channel 2 MAX31855 is connected to
the USB PC Interface
Maxim Integrated
4
MAX31855 Evaluation Kit
Evaluates: MAX31855
Troubleshooting
All effort was made to ensure that each EV kit works on the first try directly out of the box. In the rare occasion that a
problem is suspected, see the table below to help troubleshoot the issue.
SYMPTOM
CHECK
Is the LED labeled D1 on?
SOLUTION
If yes, then the electronic fuse, U7, is in a fault state.
Inspect for electrical shorts on the PCB and make sure
that the PCB is not sitting on a conductive surface.
If not, then exit the GUI and try running it again. If D2
still does not turn green, then exit the GUI and try con-
necting the USB cable to a different USB port on the
PC and wait for a Windows message that states the
hardware is ready to use. Run the GUI again.
If not, then the PCB may not be getting power from
USB. Try a different USB cable or a different USB port.
Make sure jumper, J4, is installed and connected to the
correct channel.
Verify that the thermocouple is connected (to the cor-
rect channel).
GUI says hardware not found.
Does the LED labeled D2 turn
green when the GUI is running?
Are any of the LEDs illuminated?
GUI appears to work, but the raw
data is all zeros.
The “Fault” and “Open Circuit”
indicators are red in the
Alarm
Status
section of the GUI.
Jumper (J4)
Is the thermocouple connected?
Maxim Integrated
5
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