FEATURES
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- Eight Thermocouples DAQ 8-Layer Stackable HAT for Raspberry Pi
- Supports Thermocouples type J, K, T, N, E, B, R and S
- 24 bit delta-sigma A/D converters
- Ultra-low drift (0.005µV/ºC) low offset (50µV) amplifiers
- Factory accuracy: 1%
- Maximum accuracy (through calibration): 0.1%
- Maximum acquisition speed 40 cps
- RS485/MODBUS transceiver with in and out ports
- Programmable threshold LEDs on all inputs
- Pluggable Connectors 26-16 AWG wires for power and RS485
- On-board hardware watchdog
- Reverse polarity power supply protection
- General Purpose Pushbutton
- On-board resettable fuse
- Command line
- Python library
- Node-RED example
- Modbus RTU
- OpenPLC module
DESCRIPTION
Eight Thermocouples Data Acquisition HAT for Raspberry Pi
Compatible with all Raspberry Pi versions from Zero to 4, this card offers a compact and inexpensive solution for reading and storing data from up to 64 thermocouple temperature sensors. Using 24 bit delta-sigma A/D converters with four channels each, the card achieves better than 0.1% accuracy. Field calibration with a precision 100Ω resistor can lead to 0.01% precision.
Compatible with all Raspberry Pi versions from Zero to 4, this card offers a compact and inexpensive solution for reading and storing data from up to 64 thermocouple temperature sensors. Using 24 bit delta-sigma A/D converters with four channels each, the card achieves better than 0.1% accuracy. Field calibration with a precision 100Ω resistor can lead to 0.01% precision.
COMPATIBILITY
The card is compatible with all Raspberry Pi versions from Zero to 4. It shares the I2C bus using only two of the Raspberry Pi’s GPIO pins to manage all eight cards. This feature leaves the remaining 24 GPIOs available for the user.
The card is compatible with all Raspberry Pi versions from Zero to 4. It shares the I2C bus using only two of the Raspberry Pi’s GPIO pins to manage all eight cards. This feature leaves the remaining 24 GPIOs available for the user.
POWER REQUIREMENTS
The 8-Thermocouple DAQ Card needs 5V to operate and can be powered from Raspberry Pi or from it's own pluggable connector. The cards needs 50mA to operate.
STACKING MULTIPLE CARDS
Up to eight 8-Thermocouple DAQ cards can be stacked on your Raspberry Pi. A DIP Switch is used to set the stack level of each card.
CARD LAYOUT
MECHANICAL SPECIFICATIONS
DOWNLOADS
8-Thermocouples DAQ Downloads
SOFTWARE
SOFTWARE INTERFACES
You can write your own Data Acquisition system in C, C++, PERL or the language of your choice using the Command Line functions or the Python Library. A browser interface can easily be deployed using Node-Red.
FIELD CALIBRATION
Field calibration to 0.1% precision can be achieved using an external high precision voltage reference. Software commands permit the user to calibrate the card in two points (the 2 points must be as far as possible but inside the measurement range).
RS485/MODBUS Communication
The card contains a standard RS485 transceiver which can be accessed by the local processor or by Raspberry Pi. The desired configuration is set from two bypass DIP switches. If switches are in the ON position, Raspberry Pi can communicate with any device with an RS485 interface. In this configuration the card is a passive bridge which implements only the hardware levels required by the RS485 protocol. To use this configuration, you need to tell the local processor to release control of the RS485 bus:
~$ smtc 0 cfg485wr 0 0 0 0 0
If switches are in the OFF position, the card operates as MODBUS slave and implements the MODBUS RTU protocol. Any MODBUS master can access all the card's inputs, and set all the outputs using standard MODBUS commands. A detailed list of commands implemented and parameters addresses can be found on GitHub:
In both configurations the local processor needs to be programmed to release (jumpers installed) or control (jumpers removed) the RS485 signals. See the command line online help for further information.
LED threshold signals
The 8-Thermocouples DAQ board has eight LEDs that can be activated when the input reaches a preset threshold. The threshold can be set in software for each input.
FIRMWARE UPDATE
The card firmware can be updated in the field by running a command. The update is made with the latest firmware version located on our servers. More instructions about the process can be found on GitHub. Please make sure there is no process, like Node-Red or python scripts, that tries to access the card during the update process.
DOWNLOADS
Eight Thermocouples DAQ Downloads
ACCESSORIES
DIN-RAIL MOUNTING
The 8-Thermocouples DAQ card can be installed parallel on a DIN-Rail using the DIN-Rail Kit Type 1, or perpendicular using the DIN-Rail Kit Type 2.
YOUR KIT
1. 8-Thermocouples DAQ HAT for Raspberry Pi
2. Mounting hardware
- Four M2.5x18mm male-female brass standoffs
- Four M2.5x5mm brass screws
- Four M2.5 brass nuts
4. All female connector plugs
QUICK START
- Plug your card on top of your Raspberry Pi and power up the system
- Enable I2C communication on Raspberry Pi using raspi-config.
- Install the software from github.com:
- ~$ git clone https://github.com/SequentMicrosystems/smtc-rpi.git
- ~$ cd /home/pi/smtc-rpi
- ~/smtc-rpi$ sudo make install
-
~/smtc-rpi$ smtc
The program will respond with a list of available commands.