RTD Data Acquisition Card for Raspberry Pi
Compatible with all Raspberry Pi versions from Zero to 4, tte RTD Data Acquisition Card offers a compact and inexpensive solution for reading and storing data from up to 64 RTD-100 temperature sensors. Using two ADS1248 24 bit delta-sigma converters with four channels each, the card achieves better than 0.1%. Field calibration with a precision 100Ω resistor can lead to 0.01% precision.
Since temperature measurement using RTD is based on resistance, the resistance in the lead wires and connectors must be taken into account when calculating the overall resistance in the system circuit. Using a 3-wire circuit design allows lead wire resistance to be factored out of the overall calculation. The card is compatible with all Raspberry Pi versions from Zero to 4
The card is compatible with all Raspberry Pi versions from Zero to 4.. The card share 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 Home Automation card needs 5V to operate and can be powered from Raspberry Pi or from it’s own 2.1mm barrel connector. The cards needs 50mA to operate.
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 Driver. A browser interface can easily be deployed using Node-Red.
Field calibration to 0.01% precision can be achieved using an external, 100Ω high precision resistor. Software commands permit the user to calibrate the card in two points (zeroΩ and 100Ω). The resulting values are stored in flash and used for subsequent temperature measurements.
STACKING MULTIPLE CARDS
Up to eight RTD Data Acquisition cards can be stacked on your Raspberry Pi. Each card is identified by jumpers you install to indicate the level in the stack. Cards can be installed in any order. For your convenience, two stack jumpers are provided with each card.
OPEN SOURCE HARDWARE
Install your Raspberry Pi and up to eight Home Automation cards parallel to the DIN-Rail using our DIN-RAIL Kit Type-1. Install the whole assembly perpendicular to the DIN-Rail using the DIN-RAIL Kit Type-2.
WHAT’S IN YOUR KIT
- MEGA-RTD add-on card for Raspberry Pi
- Mounting hardware
- Four M2.5x18mm male-female brass standoffs
- Four M2.5x5mm brass screws
- Four M2.5 brass nuts
- Two jumpers
- Eight 3-pin female mating connector plugs.
PT100 Thermocouples (optional)
The PT100 thermocouples have 3 wires for precise temperature measurements. They have a range of -50°C to 450°C, 2 meter long wires and a 4mm x 6mm probe.
QUICK STARTUP GUIDE
- Plug your MEGA-RTD card on top of your Raspberry Pi and power up the system.
- Enable I2C communication on Raspberry Pi using raspi-config.
- Install the MEGA-RTD software from github.com:
- ~$ git clone https://github.com/SequentMicrosystems/rtd-rpi.git
- ~$ cd /home/pi/rtd-rpi
- ~/rtd-rpi$ sudo make install
- ~/rtd-rpi$ rtd
The program will respond with a list of available commands.