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QS-KI-IN4-REVA · Rev-A · KI-IN4 / PCBV1.01

Six steps

KI Maker IN-4 Quick Start Guide

Quick-start wiring and commissioning guide for the KI Maker IN-4, a 4-channel opto-isolated 9–30 VDC input interface for 3.3 V and 5 V microcontroller and SBC projects. Start with logic power: confirm LED3PWR before applying field voltage.

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No AC mains

Field inputs are 9–30 VDC only. NO AC MAINS · LOW VOLTAGE DC ONLY.

Logic header is 3.3 V / 5 V

Never land field voltage on H1. ESP32, Pi, Pico, STM32: 3.3 V VLOGIC. Arduino Uno/Nano may use 5 V.

KI Maker IN-4 Rev-A, top view. Logic header H1 on the left, field terminals CN1–CN4 on the right.
Top view. H1 on the top right. CN1–CN4 on the bottom.
KI Maker IN-4 Rev-A, three-quarter view showing the isolation boundary and optocouplers.
Three-quarter view. Isolation boundary. OPTO ISOLATION — LOW VOLTAGE DC ONLY.

First power-up

  1. Mount and inspectFour corner holes. Field terminals on the right (IN1A/B … IN4A/B). Logic header on the left (VLOGIC, GND, OUT1–OUT4).
  2. Wire logic firstH1 pin 1 (nearest LED3PWR) to 3.3 V or 5 V. Pin 2 to controller GND. LED3PWR should light. If it does not, stop.
  3. Connect one field pairApply a valid 9–30 VDC field input across CN1 IN1A and IN1B (12 V or 24 V nominal). INxA and INxB are interchangeable. Dry contacts need that DC source in series — IN-4 does not wet the contact.
  4. Watch LED1Valid field voltage present → LED1 (IN1) on, OUT1 HIGH. Field voltage removed → LED1 off, OUT1 LOW.
  5. Land OUT1 on a GPIOH1 OUT1 to a controller digital input. Configure the GPIO as a standard digital input with its internal pull-up and pull-down resistors disabled.
  6. Repeat CN2–CN4All four channels operate independently and may be used simultaneously. Mix 12 V and 24 V as long as each pair stays 9–30 VDC.

Logic header (H1)

Pin 1 is nearest LED3PWR. OUTx is a digital logic output — connect to a controller GPIO. OUTx does not drive loads.

KI Maker IN-4 Rev-A, full board with H1 logic header in the foreground. Pin 1 VLOGIC is nearest LED3PWR.
H1 logic header. OUT1–OUT4 connect to controller GPIO/digital inputs.
Pin Silk Connect to
1VLOGICController 3.3 V or 5 V
2GNDController GND
3OUT1GPIO / digital input, channel 1
4OUT2GPIO / digital input, channel 2
5OUT3GPIO / digital input, channel 3
6OUT4GPIO / digital input, channel 4

One correct wiring

Dry contact with external 12 V or 24 VDC. IN-4 does not wet the contact.

KI Maker IN-4 Rev-A, full board with CN1–CN4 field screw terminals in the foreground.
CN1 IN1A/IN1B through CN4 IN4A/IN4B. 5.0 mm 2-pin. Silk: FIELD INPUTS — 9–30 VDC ONLY — NO AC MAINS — POLARITY INSENSITIVE.
Connection Wire
External +12 V or +24 VTo one side of the dry contact
Other side of contactINxA
0 V / field returnINxB

No + / − orientation required

Each input is polarity independent. Reverse the two field wires — the channel still works.

IN-4 documentation

Learn more about the KI Maker IN-4 isolated input board, view the KI Maker documentation library, or download the Quick Start PDF. Owner’s Manual and Specification Sheet are listed on the documentation page as they are released.

Kuster Induction Solutions LLC · KI Maker IN-4 Rev-A · PCBV1.01 · QS-KI-IN4-REVA · Low-voltage DC only · Not a certified safety device or safety-rated isolation barrier.