4x DI-ISO1211 + 4x SPST - IoTextra Octal4
4 isolated digital inputs · 4 SPST relays · galvanic isolation · 2500 VRMS
Inputs field-configurable 12/18/24/36 VDC per channel via solder jumpers · relay contacts 250 VAC / 30 VDC / 5 A · control via GPIO and/or I²C (TCA9534)
Works with Raspberry Pi, Raspberry Pi Pico / Pico 2 (RP2040 / RP2350) and ESP32
DIN-rail mounting: A 3D-printable DIN-rail mounting tray is available — view on Printables
Part of the IoTextra series · compatible with IoTsmart and IoTbase · Open Hardware
This module is a member of the IoTextra series, which serves as a fundamental building block of our ecosystem and embodies the Make Things Happy Philosophy. It is engineered to bridge the gap between rapid prototyping and industrial-grade reliability.
Hardware Synergy: The module is compatible with both IoTsmart and IoTbase series.
Software Power: This hardware compatibility unlocks the full potential of the IoTflow platform, with native support for Tasmota and Home Assistant as well. It enables you to:
- Create custom Node-RED nodes effortlessly.
- Integrate via MQTT with third-party global platforms like Blynk.
- Scale your project from a single node to a complex industrial network.
Key Specifications
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Configuration: 4 digital inputs, 4 SPST (1 Form A) relays (Panasonic APAN3105 or Hongfa HF49FD)
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Isolation: individual galvanic isolation per channel via TI ISO1211D isolated digital input receiver, 2500Vrms dielectric strength (capacitive isolation barrier), no field-side power supply required
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Digital inputs: field-configurable per channel via solder jumpers among 4 standard industrial classes — 12 / 18 / 24 / 36 VDC; polarity-independent (bipolar) input
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Relays: standard electromechanical (non-latching), 5A switching current at 250VAC/30VDC; logical "0" activates the relay (NO), logical "1" turns it off (NC)
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Control: reading input states and controlling relays is done using AP0–AP7 through the HOST-P12 connector and/or via the I²C bus through the onboard I/O expander
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I²C addressing: DIP-switch (A0–A2), up to 16 modules on one bus; I/O expander is TCA9534 or compatible (TCA9534A also supported)
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Connectors: HOST-P12, Qwiic × 2
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Status indication: LED per digital input channel, LED per relay
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Size: 47 × 56 mm, with mounting holes for base-module or Raspberry Pi installation
Operation Modes
🔌 Standalone
Connect via the HOST connector cable or Qwiic I²C connectors from any host microcontroller.
🧠 Smart
An IoTsmart module is inserted into the HOST connector. Input reading, relay control, and the 5V module supply are provided through HOST, powered from the IoTsmart module.
🏗 Mezzanine
The module is installed into an IoTbase carrier board. Input reading, relay control, and the 5V module supply are provided through HOST.
Applications
🏭 Industrial Automation — Sensor & Actuator I/O
Digital inputs read field sensors, limit switches, and proximity switches at standard industrial levels — 12VDC, 24VDC, and other configurable classes per channel; relays switch contactors, indicator lamps, or small actuators.
⚡ IIoT — Machine Status Monitoring
Inputs monitor e-stop loops, door interlocks, and voltage-presence signals across mixed voltage classes on the same module; relays drive local alarms or feed isolated status signals to a PLC.
🌱 Smart Farming — Irrigation & Climate Control
Float switches and limit switches connect to the digital inputs; relays activate pumps, valves, or heaters.
🏠 Smart Home — Entrance & Equipment Control
Inputs read gate/door position sensors and buttons; relays operate electric strikes, lighting, or general-purpose loads.
