8-Thermocouples 8-OD Outputs for Raspberry Pi Back Panel

The 8-Thermocouples 8-OD Outputs Card adds eight thermocouple inputs and eight open-drain (OD) outputs to your Raspberry Pi Back Panel for precise temperature monitoring and simple alarm/control actions. The card integrates cold-junction compensation and noise filtering for stable readings, routes all wiring cleanly through the Back Panel, and works with CLI/Python or RS485/MODBUS—so you can stack it alongside other HOP cards and scale your system with ease

FEATURES

• 8 Thermocouple Inputs
  Eight software selectable inputs can read thermocouple types J, K, T, N, E, B, R and S

• 8 Open-Drain Outputs
  Eight optically isolated open-drain outputs can drive loads up to 2A and 24VDC. Loads power must be provided by the user.

• Seamless Raspberry Pi Integration
  Plugs directly into the Raspberry Pi Back Panel — no additional wiring or hardware needed.

• Expandable Stack Design
  Stack up to 8 identical modules horizontally for larger projects.

• MODBUS Support via RS485
  Integrated RS485 port allows MODBUS RTU communication for easy industrial integration.

• Real-Time Status LEDs
  Input and output LED indicators provide immediate visual feedback.

• Built-in OLED Display
  128×32 dot matrix screen for displaying system status, messages, or sensor values.

• Cross-Platform Software Support
  Includes Python library and command-line tools for rapid development.

• OpenPLC & CODESYS Compatible
  Industrial-grade compatibility with both OpenPLC and CODESYS environments.

• No Export Restrictions
  ECCN classification EAR99 — freely exportable under U.S. regulations.

DESCRIPTION

Part of the HOP (Hardware On Panel) family developed by Sequent Microsystems, the 8-Thermocouples 8-OD Outputs Card is designed to integrate seamlessly with the Raspberry Pi Back Panel. Up to eight HOP cards—of any type—can be installed on a single Back Panel, offering maximum flexibility for industrial automation applications.

The card features:

• Eight software selectable thermocouple inputs reading type J, K, T, N, E, B, R and S thermocouples

• Eight optically isolated open-drain outputs driving loads up to 2A and 24VDC

Sixteen onboard LEDs display the real-time status of each input and output. Additional indicators show board power and signal any error condition.

An RS485 port enables external PLC or industrial controller communication using the industry-standard MODBUS RTU protocol.

• Power Supply: Back Panel provided
• 5V 35mA
• 24V 100mA

DOWNLOADS

Hardware Schematic V1.0

2D DXF Mechanical

3D STEP Model

3D Printable Enclosure

SOFTWARE

QUICK START

1. Plug the 8-Thermocouples 8-OD Outputs Card on the Back Panel for Raspberry Pi and power up the system.
2. Enable I2C communication on Raspberry Pi using raspi-config.
3. Install the software from github.com:

• git clone https://github.com/SequentMicrosystems/sequent-cli.git
• cd /home/pi/sequent-cli
• sudo make install
• sequent-cli 8thermo -h
  

FAQ

Q: What Raspberry Pi models are compatible with this card?
A: The card is compatible with all 40-pin Raspberry Pi models, including Pi 4, Pi 3, Pi 2, and Pi Zero.

Q: How is the stack level determined?
A: Stack level is automatically assigned based on the slot the card is plugged into on the Back Panel via ID0–ID2 pins.

Q: What does the watchdog function do?
A: If the Raspberry Pi fails to communicate over I²C in a set time, the watchdog cuts power for 10 seconds to trigger a system reset.

Q: What is the purpose of the Panic function?
A: The Panic input resets all outputs to their predefined default states for emergency shutdown or fail-safe scenarios.

Q: Can multiple cards be used together?
A: Yes, up to 8 cards can be stacked using the Back Panel. Each card auto-assigns its ID for seamless expansion.

Q: Is there a display on the card?
A: Yes, it features a 128×32 dot-matrix display for status, self-test, and error messages.

Q: How is communication with the Pi handled?
A: Communication is via I²C using SDA and SCL lines on the 2×20 GPIO connector.